Transcript
Dual 8-/10-/12-Bit, High Bandwidth, Multiplying DACs with Parallel Interface AD5428/AD5440/AD5447
Data Sheet FEATURES
GENERAL DESCRIPTION
10 MHz multiplying bandwidth INL of ±0.25 LSB @ 8 bits 20-lead and 24-lead TSSOP packages 2.5 V to 5.5 V supply operation ±10 V reference input 21.3 MSPS update rate Extended temperature range: −40°C to +125°C 4-quadrant multiplication Power-on reset 0.5 µA typical current consumption Guaranteed monotonic Readback function AD7528 upgrade (AD5428) AD7547 upgrade (AD5447)
The AD5428/AD5440/AD54471 are CMOS, 8-, 10-, and 12-bit, dual-channel, current output digital-to-analog converters (DACs), respectively. These devices operate from a 2.5 V to 5.5 V power supply, making them suited to battery-powered and other applications. As a result of being manufactured on a CMOS submicron process, they offer excellent 4-quadrant multiplication characteristics, with large signal multiplying bandwidths of up to 10 MHz. The DACs use data readback, allowing the user to read the contents of the DAC register via the DB pins. On power-up, the internal register and latches are filled with 0s, and the DAC outputs are at zero scale. The applied external reference input voltage (VREF) determines the full-scale output current. An integrated feedback resistor (RFB) provides temperature tracking and full-scale voltage output when combined with an external I-to-V precision amplifier.
APPLICATIONS Portable battery-powered applications Waveform generators Analog processing Instrumentation applications Programmable amplifiers and attenuators Digitally controlled calibration Programmable filters and oscillators Composite video Ultrasound Gain, offset, and voltage trimming
The AD5428 is available in a small 20-lead TSSOP package, and the AD5440/AD5447 DACs are available in small 24-lead TSSOP packages. 1
U.S. Patent Number 5,689,257.
FUNCTIONAL BLOCK DIAGRAM VREFA
AD5428/AD5440/AD5447 R
VDD DATA INPUTS
DB0
INPUT BUFFER
LATCH
DB7 DB9 DB11
RFBA IOUTA
8-/10-/12-BIT R-2R DAC A
AGND DAC A/B R CS
CONTROL LOGIC
R/W LATCH
8-/10-/12-BIT R-2R DAC B
RFBB IOUTB
DGND
VREFB
04462-001
POWER-ON RESET
Figure 1. AD5428/AD5440/AD5447 Rev. C Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Specifications subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. www.analog.com Tel: 781.329.4700 Fax: 781.461.3113 ©2004–2011 Analog Devices, Inc. All rights reserved.
AD5428/AD5440/AD5447
Data Sheet
TABLE OF CONTENTS Specifications..................................................................................... 3
Divider or Programmable Gain Element................................ 20
Timing Characteristics ................................................................ 5
Reference Selection .................................................................... 20
Absolute Maximum Ratings............................................................ 6
Amplifier Selection .................................................................... 20
ESD Caution.................................................................................. 6
Parallel Interface......................................................................... 22
Pin Configurations and Function Descriptions ........................... 7
Microprocessor Interfacing....................................................... 22
Typical Performance Characteristics ........................................... 10
PCB Layout and Power Supply Decoupling ........................... 23
Terminology .................................................................................... 15
Evaluation Board for the AD5447............................................ 23
General Description ....................................................................... 16
Power Supplies for the Evaluation Board................................ 23
DAC Section................................................................................ 16
Bill of Materials............................................................................... 27
Circuit Operation ....................................................................... 16
Overview of AD54xx Devices....................................................... 28
Single-Supply Applications ....................................................... 19
Outline Dimensions ....................................................................... 29
Adding Gain................................................................................ 19
Ordering Guide .......................................................................... 29
REVISION HISTORY 8/11—Rev. B to Rev. C Changes to CS Pin Description, Table 6 ........................................ 9 3/11—Rev. A to Rev. B Changes to Evaluation Board For the AD5447 Section ............ 23 Changes to Figure 47 Caption....................................................... 24 Changes to Figure 49...................................................................... 25 Change to U1 Description in Table 12......................................... 27 Change to Ordering Guide............................................................ 29 7/05—Rev. 0 to Rev. A Changed Pin DAC A/B to DAC A/B................................Universal Changes to Features List .................................................................. 1 Changes to Specifications ................................................................ 3 Changes to Timing Characteristics ................................................ 5 Change to Figure 2 ........................................................................... 5 Change to Absolute Maximum Ratings Section........................... 6 Change to Figure 13, Figure 14, and Figure 18........................... 11 Change to Figure 32 Through Figure 34 ..................................... 14
Changes to General Description Section .................................... 16 Changes to Figure 37...................................................................... 16 Changes to Single-Supply Applications Section......................... 19 Changes to Figure 40 Through Figure 42.................................... 19 Changes to Divider or Programmable Gain Element Section .... 20 Changes to Figure 43...................................................................... 20 Changes to Table 9 Through Table 11 ......................................... 21 Changes to Microprocessor Interfacing Section ........................ 22 Added Figure 44 Through Figure 46 ........................................... 22 Added 8xC51-to-AD5428/AD5440/AD5447 Interface Section ........................................................................ 22 Added ADSP-BF5xx-to-AD5428/AD5440/AD5447 Interface Section ........................................................................ 22 Changes to Power Supplies for the Evaluation Board Section.... 23 Changes to Table 13 ....................................................................... 28 Updated Outline Dimensions....................................................... 29 Changes to Ordering Guide .......................................................... 29 7/04—Revision 0: Initial Version
Rev. C | Page 2 of 32
Data Sheet
AD5428/AD5440/AD5447
SPECIFICATIONS 1 VDD = 2.5 V to 5.5 V, VREF = 10 V, IOUT2 = 0 V. Temperature range for Y version: −40°C to +125°C. All specifications TMIN to TMAX, unless otherwise noted. DC performance is measured with OP177, and ac performance is measured with AD8038, unless otherwise noted. Table 1. Parameter STATIC PERFORMANCE AD5428 Resolution Relative Accuracy Differential Nonlinearity AD5440 Resolution Relative Accuracy Differential Nonlinearity AD5447 Resolution Relative Accuracy Differential Nonlinearity Gain Error Gain Error Temperature Coefficient Output Leakage Current REFERENCE INPUT Reference Input Range VREFA, VREFB Input Resistance VREFA-to-VREFB Input Resistance Mismatch Input Capacitance Code 0 Code 4095 DIGITAL INPUTS/OUTPUT Input High Voltage, VIH
Min
Typ
8
±10 10 1.6
Measured to ±1 mV of FS Measured to ±4 mV of FS Measured to ±16 mV of FS Digital Delay 10% to 90% Settling Time Digital-to-Analog Glitch Impulse
Conditions
8 ±0.25 ±1
Bits LSB LSB
Guaranteed monotonic
10 ±0.5 ±1
Bits LSB LSB
Guaranteed monotonic
12 ±1 –1/+2 ±25 ±5 ±15
Bits LSB LSB mV ppm FSR/°C nA nA
13 2.5
V kΩ %
Guaranteed monotonic
Data = 0x0000, TA = 25°C Data = 0x0000
Input resistance TC = –50 ppm/°C Typ = 25°C, max = 125°C
3.5 3.5
pF pF VDD = 3.6 V to 5.5 V VDD = 2.5 V to 3.6 V VDD = 2.7 V to 5.5 V VDD = 2.5 V to 2.7 V VDD = 4.5 V to 5.5 V, ISOURCE = 200 μA VDD = 2.5 V to 3.6 V, ISOURCE = 200 μA VDD = 4.5 V to 5.5 V, ISINK = 200 μA VDD = 2.5 V to 3.6 V, ISINK = 200 μA
4
V V V V V V V V μA pF MHz
VREF = ±3.5 V p-p, DAC loaded all 1s RLOAD = 100 Ω, CLOAD = 15 pF, VREF = 10 V DAC latch alternately loaded with 0s and 1s
1.7 1.7 0.8 0.7 VDD − 1 VDD − 0.5
Output Low Voltage, VOL Input Leakage Current, IIL Input Capacitance DYNAMIC PERFORMANCE Reference-Multiplying BW Output Voltage Settling Time
Unit
±5
Input Low Voltage, VIL Output High Voltage, VOH
Max
0.4 0.4 1 10
10
80 35 30 20 15 3
120 70 60 40 30
ns ns ns ns ns nV-sec
Rev. C | Page 3 of 32
Interface delay time Rise and fall times, VREF = 10 V, RLOAD = 100 Ω 1 LSB change around major carry, VREF = 0 V
AD5428/AD5440/AD5447 Parameter Multiplying Feedthrough Error
Data Sheet Min
Output Capacitance
12 25 1
Digital Feedthrough Output Noise Spectral Density Analog THD Digital THD 100 kHz fOUT 50 kHz fOUT SFDR Performance (Wide Band) Clock = 10 MHz 500 kHz fOUT 100 kHz fOUT 50 kHz fOUT Clock = 25 MHz 500 kHz fOUT 100 kHz fOUT 50 kHz fOUT SFDR Performance (Narrow Band) Clock = 10 MHz 500 kHz fOUT 100 kHz fOUT 50k Hz fOUT Clock = 25 MHz 500 kHz fOUT 100 kHz fOUT 50 kHz fOUT Intermodulation Distortion f1 = 40 kHz, f2 = 50 kHz f1 = 40 kHz, f2 = 50 kHz POWER REQUIREMENTS Power Supply Range IDD
Typ
Unit
70 48 17 30
dB dB pF pF nV-sec
25 81
nV/√Hz dB
61 66
dB dB
Conditions DAC latches loaded with all 0s, VREF = ±3.5 V 1 MHz 10 MHz DAC latches loaded with all 0s DAC latches loaded with all 1s Feedthrough to DAC output with CS high and alternate loading of all 0s and all 1s @ 1 kHz VREF = 3.5 V p-p, all 1s loaded, f = 100 kHz Clock = 10 MHz, VREF = 3.5 V
AD5447, 65k codes, VREF = 3.5 V 55 63 65
dB dB dB
50 60 62
dB dB dB AD5447, 65k codes, VREF = 3.5 V
73 80 87
dB dB dB
70 75 80
dB dB dB
72 65
dB dB
AD5447, 65k codes, VREF = 3.5 V Clock = 10 MHz Clock = 25 MHz
V μA μA %/%
TA = 25°C, logic inputs = 0 V or VDD TA = −40°C to +125°C, logic inputs = 0 V or VDD ∆VDD = ±5%
2.5 0.5
Power Supply Sensitivity 1
Max
5.5 0.7 10 0.001
Guaranteed by design, not subject to production test.
Rev. C | Page 4 of 32
Data Sheet
AD5428/AD5440/AD5447
TIMING CHARACTERISTICS All input signals are specified with tr = tf = 1 ns (10% to 90% of VDD) and timed from a voltage level of (VIL + VIH)/2. VDD = 2.5 V to 5.5 V, VREF = 10 V, IOUT2 = 0 V, temperature range for Y version: −40°C to +125°C. All specifications TMIN to TMAX, unless otherwise noted. Table 2. Parameter 1 Write Mode t1 t2 t3 t4 t5 t6 t7 t8 t9 Data Readback Mode t10 t11 t12 t13 Update Rate
Unit
Conditions/Comments
0 0 10 10 0 6 0 5 7
ns min ns min ns min ns min ns min ns min ns min ns min ns min
R/W to CS setup time R/W to CS hold time CS low time Address setup time Address hold time Data setup time Data hold time R/W high to CS low CS min high time
0 0 5 25 5 10 21.3
ns typ ns typ ns typ ns max ns typ ns max MSPS
Address setup time Address hold time Data access time Bus relinquish time Consists of CS min high time, CS low time, and output voltage settling time
Guaranteed by design and characterization, not subject to production test.
R/W
t1
t2
t8
t2
t9 t3
CS
t5
t4
t11
t10
DACA/DACB
t12
t7
DATA VALID
DATA
t13 DATA VALID
Figure 2. Timing Diagram
200μA
TO OUTPUT PIN
IOL
VOH (MIN) + VOL (MAX) 2
CL 50pF 200μA
IOH
Figure 3. Load Circuit for Data Output Timing Specifications
Rev. C | Page 5 of 32
04462-002
t8
04462-003
1
Limit at TMIN, TMAX
AD5428/AD5440/AD5447
Data Sheet
ABSOLUTE MAXIMUM RATINGS Transient currents of up to 100 mA do not cause SCR latch-up. TA = 25°C, unless otherwise noted. Table 3. Parameter VDD to GND VREFA, VREFB, RFBA, RFBB to DGND IOUT1, IOUT2 to DGND Logic Inputs and Output1 Operating Temperature Range Automotive (Y Version) Storage Temperature Range Junction Temperature 20-lead TSSOP θJA Thermal Impedance 24-lead TSSOP θJA Thermal Impedance Lead Temperature, Soldering (10 sec) IR Reflow, Peak Temperature (<20 sec) 1
Rating –0.3 V to +7 V –12 V to +12 V –0.3 V to +7 V –0.3 V to VDD + 0.3 V –40°C to +125°C –65°C to +150°C 150°C 143°C/W 128°C/W 300°C 235°C
Stresses above those listed in Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; functional operation of the device at these or any other conditions above those listed in the operational sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Only one absolute maximum rating may be applied at any one time.
ESD CAUTION
Overvoltages at DBx, CS, and R/W are clamped by internal diodes.
Rev. C | Page 6 of 32
Data Sheet
AD5428/AD5440/AD5447
PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS AGND 1
20
IOUTB
IOUTA 2
19
RFBB
RFBA 3
18
VREFB
17
VDD
VREFA 4 DGND 5
AD5428 TOP VIEW (Not to Scale)
R/W
15
CS
DB7 7
14
DB0 (LSB)
DB6 8
13
DB1
DB5 9
12
DB2
DB4 10
11
DB3
04462-004
16
DAC A/B 6
Figure 4. Pin Configuration 20-Lead TSSOP (RU-20)
Table 4. AD5428 Pin Function Descriptions Pin No. 1
Mnemonic AGND
2, 20 3, 19
IOUTA, IOUTB RFBA, RFBB
4, 18 5 6 7 to14 15
VREFA, VREFB DGND DAC A/B DB7 to DB0 CS
16
R/W
17
VDD
Description DAC Ground Pin. This pin should typically be tied to the analog ground of the system, but can be biased to achieve single-supply operation. DAC Current Outputs. DAC Feedback Resistor Pins. These pins establish voltage output for the DAC by connecting to an external amplifier output. DAC Reference Voltage Input Terminals. Digital Ground Pin. Selects DAC A or DAC B. Low selects DAC A; high selects DAC B. Parallel Data Bits 7 Through 0. Chip Select Input. Active low. Used in conjunction with R/W to load parallel data to the input latch or to read data from the DAC register. Read/Write. When low, used in conjunction with CS to load parallel data. When high, used in conjunction with CS to read back contents of the DAC register. Positive Power Supply Input. This part can be operated from a supply of 2.5 V to 5.5 V.
Rev. C | Page 7 of 32
AD5428/AD5440/AD5447
Data Sheet
AGND 1
24
IOUTB
IOUTA 2
23
RFBB
RFBA 3
22
VREFB
VREFA 4
AD5440
21
VDD
DGND 5
TOP VIEW (Not to Scale)
20
R/W CS
18
NC
DB8 8
17
NC
DB7 9
16
DB0 (LSB)
DB6 10
15
DB1
DB5 11
14
DB2
DB4 12
13
DB3
04462-005
19
DB9 7
DAC A/B 6
NC = NO CONNECT
Figure 5. Pin Configuration 24-Lead TSSOP (RU-24)
Table 5. AD5440 Pin Function Descriptions Pin No. 1
Mnemonic AGND
2, 24
IOUTA, IOUTB
3, 23
RFBA, RFBB
4, 22 5 6 7 to16
VREFA, VREFB DGND DAC A/B DB9 to DB0
19
CS
20
R/W
21
VDD
Function DAC Ground Pin. This pin should typically be tied to the analog ground of the system, but can be biased to achieve single-supply operation. DAC Current Outputs. DAC Feedback Resistor Pins. Establish voltage output for the DAC by connecting to an external amplifier output. DAC Reference Voltage Input Terminals. Digital Ground Pin. Selects DAC A or DAC B. Low selects DAC A; high selects DAC B. Parallel Data Bits 9 Through 0. Chip Select Input. Active low. Used in conjunction with R/W to load parallel data to the input latch or to read data from the DAC register. Read/Write. When low, used in conjunction with CS to load parallel data. When high, used in conjunction with CS to read back contents of the DAC register. Positive Power Supply Input. This part can be operated from a supply of 2.5 V to 5.5 V.
Rev. C | Page 8 of 32
Data Sheet
AD5428/AD5440/AD5447
AGND 1
24
IOUTB
IOUTA 2
23
RFBB
RFBA 3
22
VREFB
VREFA 4
AD5447
21
VDD
DGND 5
TOP VIEW (Not to Scale)
20
R/W CS
18
DB0 (LSB)
DB10 8
17
DB1
DB9 9
16
DB2
DB8 10
15
DB3
DB7 11
14
DB4
DB6 12
13
DB5
04462-006
19
DB11 7
DAC A/B 6
Figure 6. Pin Configuration 24-Lead TSSOP (RU-24)
Table 6. AD5447 Pin Function Descriptions Pin No. 1
Mnemonic AGND
2, 24 3, 23
IOUTA, IOUTB RFBA, RFBB
4, 22 5 6 7 to 18 19
VREFA, VREFB DGND DAC A/B DB11 to DB0 CS
20
R/W
21
VDD
Description DAC Ground Pin. This pin should typically be tied to the analog ground of the system, but can be biased to achieve single-supply operation. DAC Current Outputs. DAC Feedback Resistor Pins. Establish voltage output for the DAC by connecting to an external amplifier output. DAC Reference Voltage Input Terminals. Digital Ground Pin. Selects DAC A or DAC B. Low selects DAC A; high selects DAC B. Parallel Data Bits 11 Through 0. Chip Select Input. Active low. Used in conjunction with R/W to load parallel data to the input latch or to read data from the DAC register. Read/Write. When low, used in conjunction with CS to load parallel data. When high, used in conjunction with CS to read back the contents of the DAC register. When CS and R/W are held low, the latches are transparent. Any changes on the data lines are reflected in the relevant DAC output. Positive Power Supply Input. This part can be operated from a supply of 2.5 V to 5.5 V.
Rev. C | Page 9 of 32
AD5428/AD5440/AD5447
Data Sheet
TYPICAL PERFORMANCE CHARACTERISTICS 0.20
0.20
0.10
0.05
0.05
DNL (LSB)
0.10
0
0
–0.05
–0.05
–0.10
–0.10
–0.15
–0.15
–0.20 0
50
TA = 25°C VREF = 10V VDD = 5V
0.15
100
150
200
250
CODE
–0.20
04462-007
0
50
200
250
Figure 10. DNL vs. Code (8-Bit DAC)
0.5
0.5
0.3
0.3 0.2
0.1
0.1
DNL (LSB)
0.2
0 –0.1
0 –0.1
–0.2
–0.2
–0.3
–0.3
–0.4
–0.4
200
400
600
800
1000
CODE
–0.5
04462-008
–0.5 0
TA = 25°C VREF = 10V VDD = 5V
0.4
0
200
400
600
800
1000
CODE
Figure 8. INL vs. Code (10-Bit DAC)
04462-011
TA = 25°C VREF = 10V VDD = 5V
0.4
INL (LSB)
150 CODE
Figure 7. INL vs. Code (8-Bit DAC)
Figure 11. DNL vs. Code (10-Bit DAC)
1.0
1.0 TA = 25°C VREF = 10V VDD = 5V
0.8 0.6
0.6 0.4
0.2
0.2
DNL (LSB)
0.4
0 –0.2
0 –0.2
–0.4
–0.4
–0.6
–0.6
–0.8
–0.8
–1.0 0
500
1000
TA = 25°C VREF = 10V VDD = 5V
0.8
1500
2000
2500
3000
CODE
3500
4000
04462-009
INL (LSB)
100
Figure 9. INL vs. Code (12-Bit DAC)
–1.0 0
500
1000
1500
2000
2500
3000
CODE
Figure 12. DNL vs. Code (12-Bit DAC)
Rev. C | Page 10 of 32
3500
4000
04462-012
INL (LSB)
0.15
04462-010
TA = 25°C VREF = 10V VDD = 5V
Data Sheet
AD5428/AD5440/AD5447
0.6 8 TA = 25°C
0.5 7
0.4 MAX INL
6 CURRENT (mA)
INL (LSB)
0.3 0.2 TA = 25°C VDD = 5V
0.1 0
VDD = 5V
5 4 3
MIN INL –0.1
2
–0.2
VDD = 3V
1
3
4
5
6
7
8
9
10
REFERENCE VOLTAGE
VDD = 2.5V 0 0
0.5
1.5
1.0
2.0
2.5
3.0
3.5
4.0
4.5
5.0
INPUT VOLTAGE (V)
Figure 13. INL vs. Reference Voltage
04462-022
2
04462-013
–0.3
Figure 16. Supply Current vs. Logic Input Voltage
1.6
–0.40 TA = 25°C VDD = 5V
1.4
–0.45
1.2 IOUT1 VDD = 5V IOUT1 LEAKAGE (nA)
–0.55
–0.60 MIN DNL –0.65
1.0 0.8 IOUT1 VDD = 3V 0.6 0.4
2
3
4
5
6
7
8
9
10
REFERENCE VOLTAGE
0 –40
04462-014
–0.70
0
20
40
60
80
100
120
TEMPERATURE (°C)
Figure 17. IOUT1 Leakage Current vs. Temperature
Figure 14. DNL vs. Reference Voltage
0.50
5
0.45
4 VDD = 5V
3
VDD = 5V
0.40 0.35
CURRENT (μA)
2 1 0 VDD = 2.5V
–1
ALL 0s 0.30
–3
0.10 VREF = 10V
–5 –60
–40
–20
VDD = 2.5V
0.20 0.15
–4
ALL 1s
0.25
–2
ALL 1s
ALL 0s
0.05
0
20
40
60
80
100
TEMPERATURE (°C)
120
140
04462-015
ERROR (mV)
–20
04462-023
0.2
Figure 15. Gain Error vs. Temperature
0 –60
–40
–20
0
20
40
60
80
100
TEMPERATURE (°C)
Figure 18. Supply Current vs. Temperature
Rev. C | Page 11 of 32
120
140
04462-024
DNL (LSB)
–0.50
AD5428/AD5440/AD5447
Data Sheet
14
3
TA = 25°C LOADING ZS TO FS VDD = 5V
0
6
GAIN (dB)
VDD = 3V
–3
4 VDD = 2.5V
VREF = ±2V, AD8038 CC 1.47pF VREF = ±2V, AD8038 CC 1pF VREF = ±0.15V, AD8038 CC 1pF VREF = ±0.15V, AD8038 CC 1.47pF VREF = ±3.51V, AD8038 CC 1.8pF
–6
2
1
10
100
1k
10k
100k
1M
10M
04462-025
0 100M
FREQUENCY (Hz)
–9 10k
0.045
ALL ON DB11 DB10 DB9 DB8 DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0
10
100
0x7FF TO 0x800
1M
10M
100M
OUTPUT VOLTAGE (V)
TA = 25°C VDD = 5V VREF = ±3.5V CCOMP = 1.8pF AMP = AD8038
1k 10k 100k FREQUENCY (Hz)
100M
TA = 25°C VREF = 0V AMP = AD8038 CCOMP = 1.8pF
VDD = 5V
0.035
ALL OFF 1
10M
0.040
0.030 0.025
VDD = 3V
0.020 0.015 0x800 TO 0x7FF 0.010 VDD = 3V
0.005 0 –0.005
04462-026
GAIN (dB)
TA = 25°C LOADING ZS TO FS
1M FREQUENCY (Hz)
Figure 22. Reference Multiplying Bandwidth vs. Frequency and Compensation Capacitor
Figure 19. Supply Current vs. Update Rate
6 0 –6 –12 –18 –24 –30 –36 –42 –48 –54 –60 –66 –72 –78 –84 –90 –96 –102
100k
VDD = 5V
–0.010 0
20
40
60
80
100
120
140
160
180
200
TIME (ns)
Figure 20. Reference Multiplying Bandwidth vs. Frequency and Code
Figure 23. Midscale Transition, VREF = 0 V
–1.68
0.2
TA = 25°C VREF = 3.5V AMP = AD8038 CCOMP = 1.8pF
0x7FF TO 0x800 –1.69 VDD = 5V OUTPUT VOLTAGE (V)
–1.70
–0.2
–0.4
TA = 25°C VDD = 5V VREF = ±3.5V CCOMP = 1.8pF AMP = AD8038
–0.6
10
100
–1.72 VDD = 3V
–1.73
VDD = 5V
–1.74
VDD = 3V
–1.76 0x800 TO 0x7FF
–0.8 1
–1.71
–1.75
1k
10k
100k
1M
10M
100M
FREQUENCY (Hz)
04462-027
GAIN (dB)
0
–1.77
Figure 21. Reference Multiplying Bandwidth—All 1s Loaded
0
20
40
60
80
100
120
140
160
TIME (ns)
Figure 24. Midscale Transition, VREF = 3.5 V
Rev. C | Page 12 of 32
180
200
04462-042
IDD (mA)
8
04462-028
10
TA = 25°C VDD = 5V
04462-041
12
Data Sheet
AD5428/AD5440/AD5447 90
20
TA = 25°C VDD = 3V AMP = AD8038
0
80 MCLK = 5MHz 70
SFDR (dB)
–40
FULL SCALE ZERO SCALE
30
–80
20
–100
10
1
100
10
1k
10k
100k
MCLK = 25MHz
40
1M
10M
FREQUENCY (Hz)
TA = 25°C VREF = 3.5V AMP = AD8038
0 0
100
200
300
400
500
600
700
900
1000
fOUT (kHz)
Figure 25. Power Supply Rejection Ratio vs. Frequency
Figure 28. Wideband SFDR vs. fOUT Frequency
–60
0 TA = 25°C VDD = 3V VREF = 3.5V p-p
–65
800
04462-046
–60
50
04462-043
PSRR (dB)
–20
–120
MCLK = 10MHz
60
TA = 25°C VDD = 5V AMP = AD8038 65k CODES
–10 –20 –30 SFDR (dB)
THD + N (dB)
–70
–75
–40 –50 –60
–80
–70 –85
1
10
100
1k
10k
100k
1M
FREQUENCY (Hz)
–90
04462-044
–90
2
0
Figure 26. THD + Noise vs. Frequency
4
6 8 FREQUENCY (MHz)
10
12
04462-047
–80
Figure 29. Wideband SFDR, fOUT = 100 kHz, Clock = 25 MHz
100
0
TA = 25°C VDD = 5V AMP = AD8038 65k CODES
MCLK = 1MHz
–10 80
–20
SFDR (dB)
MCLK = 0.5MHz 40
–40 –50 –60 –70
20
–80
TA = 25°C VREF = 3.5V AMP = AD8038 0
20
40
60
80
100
120
140
160
180
fOUT (kHz)
200
–90
Figure 27. Wideband SFDR vs. fOUT Frequency
–100 0
0.5
1.0
1.5
2.0 2.5 3.0 3.5 FREQUENCY (MHz)
4.0
4.5
5.0
Figure 30. Wideband SFDR, fOUT = 500 kHz, Clock = 10 MHz
Rev. C | Page 13 of 32
04462048
0
04462-045
SFDR (dB)
–30 MCLK = 200kHz
60
AD5428/AD5440/AD5447 0
Data Sheet 0
TA = 25°C VDD = 5V AMP = AD8038 65k CODES
–10
–20
–20
–30 IMD (dB)
–40 –50
–40 –50 –60
–60
–70
–70
–80
–80
0.5
1.0
1.5
2.0 2.5 3.0 3.5 FREQUENCY (MHz)
4.0
4.5
5.0
Figure 31. Wideband SFDR, fOUT = 50 kHz, Clock = 10 MHz
0
–100 70
–20
85
95 90 100 105 FREQUENCY (kHz)
0
110
115
120
TA = 25°C VDD = 5V AMP = AD8038 65k CODES
–10 –20
–30 IMD (dB)
–30
–40 –50
–40 –50 –60
–70
–70
–80
–80
–90
–90
300
350
400
450 500 550 600 FREQUENCY (kHz)
650
700
750
04462-050
–60
–100 250
80
Figure 34. Narrow-Band IMD, fOUT = 90 kHz, 100 kHz, Clock = 10 MHz
TA = 25°C VDD = 3V AMP = AD8038 65k CODES
–10
75
04462-052
0
04462-049
–90
–90
–100 0
Figure 32. Narrow-Band SFDR, fOUT = 500 kHz, Clock = 25 MHz
50
100
150 200 250 FREQUENCY (kHz)
TA = 25°C VDD = 3V AMP = AD8038 65k CODES
0
350
400
Figure 35. Wideband IMD, fOUT = 90 kHz, 100 kHz, Clock = 25 MHz
300
20
300
04462-53
SFDR (dB)
–30
SFDR (dB)
TA = 25°C VDD = 3V AMP = AD8038 65k CODES
–10
TA = 25°C AMP = AD8038
ZERO SCALE LOADED TO DAC 250
MIDSCALE LOADED TO DAC
OUTPUT NOISE (nV/ Hz)
FULL SCALE LOADED TO DAC
–40 –60 –80
150
100
50
60
70
80
90 100 110 120 FREQUENCY (kHz)
130
140
150
04462-051
–100 –120 50
200
0 100
1k
10k FREQUENCY (Hz)
Figure 36. Output Noise Spectral Density Figure 33. Narrow-Band SFDR, fOUT = 100 kHz, Clock = 25 MHz
Rev. C | Page 14 of 32
100k
04462-054
SFDR (dB)
–20
Data Sheet
AD5428/AD5440/AD5447
TERMINOLOGY Relative Accuracy (Endpoint Nonlinearity) A measure of the maximum deviation from a straight line passing through the endpoints of the DAC transfer function. It is measured after adjusting for zero and full scale and is typically expressed in LSBs or as a percentage of the full-scale reading. Differential Nonlinearity The difference in the measured change and the ideal 1 LSB change between two adjacent codes. A specified differential nonlinearity of −1 LSB maximum over the operating temperature range ensures monotonicity. Gain Error (Full-Scale Error) A measure of the output error between an ideal DAC and the actual device output. For these DACs, ideal maximum output is VREF – 1 LSB. The gain error of the DACs is adjustable to zero with an external resistance. Output Leakage Current The current that flows into the DAC ladder switches when they are turned off. For the IOUT1 terminal, it can be measured by loading all 0s to the DAC and measuring the IOUT1 current. Minimum current flows into the IOUT2 line when the DAC is loaded with all 1s. Output Capacitance Capacitance from IOUT1 or IOUT2 to AGND. Output Current Settling Time The amount of time for the output to settle to a specified level for a full-scale input change. For these devices, it is specified with a 100 Ω resistor to ground. Digital-to-Analog Glitch Impulse The amount of charge injected from the digital inputs to the analog output when the inputs change state. This is normally specified as the area of the glitch in either pA-sec or nV-sec, depending on whether the glitch is measured as a current or voltage signal.
Digital Feedthrough When the device is not selected, high frequency logic activity on the device’s digital inputs is capacitively coupled through the device and produces noise on the IOUT pins and, subsequently, on the following circuitry. This noise is digital feedthrough. Multiplying Feedthrough Error The error due to capacitive feedthrough from the DAC reference input to the DAC IOUT1 terminal when all 0s are loaded to the DAC. Total Harmonic Distortion (THD) The DAC is driven by an ac reference. The ratio of the rms sum of the harmonics of the DAC output to the fundamental value is the THD. Usually only the lower-order harmonics are included, such as second to fifth harmonics.
THD = 20 log
V 2 2 + V3 2 + V4 2 + V5 2 V1
Digital Intermodulation Distortion Second-order intermodulation distortion (IMD) measurements are the relative magnitude of the fa and fb tones digitally generated by the DAC and the second-order products at 2fa − fb and 2fb − fa. Spurious-Free Dynamic Range (SFDR) SFDR is the usable dynamic range of a DAC before spurious noise interferes or distorts the fundamental signal. SFDR is the measure of difference in amplitude between the fundamental and the largest harmonic or nonharmonic spur from dc to full Nyquist bandwidth (half the DAC sampling rate, or fs/2). Narrow-band SFDR is a measure of SFDR over an arbitrary window size, in this case 50%, of the fundamental. Digital SFDR is a measure of the usable dynamic range of the DAC when the signal is a digitally generated sine wave.
Rev. C | Page 15 of 32
AD5428/AD5440/AD5447
Data Sheet
GENERAL DESCRIPTION CIRCUIT OPERATION
DAC SECTION The AD5428/AD5440/AD5447 are CMOS 8-, 10-, and 12-bit, dual-channel, current output DACs consisting of a standard inverting R-2R ladder configuration. Figure 37 shows a simplified diagram for a single channel of the 8-bit AD5428. The feedback resistor RFBA has a value of R. The value of R is typically 10 kΩ (with a minimum of 8 kΩ and a maximum of 12 kΩ). If IOUT1 and AGND are kept at the same potential, a constant current flows into each ladder leg, regardless of digital input code. Therefore, the input resistance presented at VREFA is always constant and nominally of value R. The DAC output (IOUT) is code-dependent, producing various resistances and capacitances. When choosing an external amplifier, take into account the variation in impedance generated by the DAC on the amplifier’s inverting input node. R
R
Using a single op amp, these devices can easily be configured to provide 2-quadrant multiplying operation or a unipolar output voltage swing, as shown in Figure 38. When an output amplifier is connected in unipolar mode, the output voltage is given by VOUT = − VREF × D / 2n
where: D is the fractional representation of the digital word loaded to the DAC. D = 0 to 255 (8-bit AD5428) = 0 to 1023 (10-bit AD5440) = 0 to 4095 (12-bit AD5447) n is the resolution of the DAC.
R
2R
2R
2R
2R
S1
S2
S3
S8
Note that the output voltage polarity is opposite to the VREF polarity for dc reference voltages. These DACs are designed to operate with either negative or positive reference voltages. The VDD power pin is only used by the internal digital logic to drive the on and off states of the DAC switches.
2R R
RFBA IOUTA AGND
DAC DATA LATCHES AND DRIVERS
04462-029
VREF
Unipolar Mode
These DACs are also designed to accommodate ac reference input signals in the range of –10 V to +10 V.
Figure 37. Simplified Ladder
Access is provided to the VREF, RFB, and IOUT terminals of DAC A and DAC B, making the devices extremely versatile and allowing them to be configured in several operating modes, such as unipolar output mode, 4-quadrant multiplication bipolar mode, or single-supply mode. Note that a matching switch is used in series with the internal RFBA feedback resistor. If users attempt to measure RFBA, power must be applied to VDD to achieve continuity.
With a fixed 10 V reference, the circuit in Figure 38 gives a unipolar 0 V to –10 V output voltage swing. When VIN is an ac signal, the circuit performs 2-quadrant multiplication. Table 7 shows the relationship between digital code and the expected output voltage for unipolar operation using the 8-bit AD5428. Table 7. Unipolar Code Digital Input 1111 1111 1000 0000 0000 0001 0000 0000
Rev. C | Page 16 of 32
Analog Output (V) –VREF (255/256) –VREF(128/256) = –VREF/2 –VREF (1/256) –VREF (0/256) = 0
Data Sheet
AD5428/AD5440/AD5447 VINA (±10V) R11
VREFA
AD5428/AD5440/AD5447
R
RFBA
R21
VDD C12 IOUTA
DB0 INPUT BUFFER
LATCH
8-/10-/12-BIT R-2R DAC A
VOUTA
DB7 DB9 DB11
AGND
DAC A/B
R CONTROL LOGIC
CS
RFBB
AGND
R41 C22
IOUTB
R/W LATCH
8-/10-/12-BIT R-2R DAC B
VOUTB
DGND AGND POWER-ON RESET VREFB
R31 VINB (±10V) 1R1, 2C1,
R2 AND R3, R4 USED ONLY IF GAIN ADJUSTMENT IS REQUIRED. C2 PHASE COMPENSATION (1pF TO 2pF) IS REQUIRED WHEN USING HIGH SPEED AMPLIFIERS TO PREVENT RINGING OR OSCILLATION.
Figure 38. Unipolar Operation
Rev. C | Page 17 of 32
04462-030
DATA INPUTS
AD5428/AD5440/AD5447
Data Sheet
Bipolar Operation
Table 8. Bipolar Code
In some applications, it may be necessary to generate full 4-quadrant multiplying operation or a bipolar output swing. This can easily be accomplished by using another external amplifier and some external resistors, as shown in Figure 39. In this circuit, the second amplifier, A2, provides a gain of 2. Biasing the external amplifier with an offset from the reference voltage results in full 4-quadrant multiplying operation. The transfer function of this circuit shows that both negative and positive output voltages are created as the input data (D) is incremented from Code 0 (VOUT = −VREF) to midscale (VOUT = 0 V) to full scale (VOUT = +VREF). When connected in bipolar mode, the output voltage is given by
Digital Input 1111 1111 1000 0000 0000 0001 0000 0000
Analog Output (V) +VREF (127/128) 0 –VREF (127/128) –VREF (128/128)
Stability In the I-to-V configuration, the IOUT of the DAC and the inverting node of the op amp must be connected as close as possible, and proper PCB layout techniques must be used. Because every code change corresponds to a step function, gain peaking may occur if the op amp has limited gain bandwidth product (GBP) and there is excessive parasitic capacitance at the inverting node. This parasitic capacitance introduces a pole into the open-loop response, which can cause ringing or instability in the closedloop applications circuit.
VOUT = (V REF × D / 2 n −1 ) − V REF where: D is the fractional representation of the digital word loaded to the DAC. D = 0 to 255 (AD5428) = 0 to 1023 (AD5440) = 0 to 4095 (AD5447) n is the number of bits.
An optional compensation capacitor, C1, can be added in parallel with RFBA for stability, as shown in Figure 38 and Figure 39. Too small a value of C1 can produce ringing at the output, whereas too large a value can adversely affect the settling time. C1 should be found empirically, but 1 pF to 2 pF is generally adequate for the compensation.
When VIN is an ac signal, the circuit performs 4-quadrant multiplication. Table 8 shows the relationship between digital code and the expected output voltage for bipolar operation using the 8-bit AD5428. VINA (±10V)
R5 20kΩ
R11 R62 20kΩ
VREFA
AD5428/AD5440/AD5447
R
RFBA
R72 10kΩ
R21
A2 VOUTA
VDD C13 DB0
IOUTA INPUT BUFFER
LATCH
8-/10-/12-BIT R-2R DAC A
A1 AGND
DB7 DB9 DB11
DAC A/B CS
AGND
AGND
R
RFBB
R41
CONTROL LOGIC
C23 IOUTB
R/W LATCH
A3
8-/10-/12-BIT R-2R DAC B
DGND AGND
R8 20kΩ
R92 10kΩ
A4
R102 20kΩ
POWER-ON RESET VREFB
VOUTB R12 5kΩ
R31
AGND
VINB (±10V) 1R1, R2 AND R3, R4 USED ONLY IF GAIN ADJUSTMENT IS REQUIRED. ADJUST R1 FOR V OUTA = 0V WITH CODE 10000000 IN DAC A LATCH. ADJUST R3 FOR VOUTB = 0V WITH CODE 10000000 IN DAC B LATCH. 2MATCHING AND TRACKING IS ESSENTIAL FOR RESISTOR PAIRS R6, R7 AND R9, R10. 3C1, C2 PHASE COMPENSATION (1pF TO 2pF) MAY BE REQUIRED IF A1/A3 IS A HIGH SPEED AMPLIFIER.
Figure 39. Bipolar Operation (4-Quadrant Multiplication) Rev. C | Page 18 of 32
04462-031
DATA INPUTS
R11 5kΩ
Data Sheet
AD5428/AD5440/AD5447 VDD = 5V
SINGLE-SUPPLY APPLICATIONS
ADR03
Voltage-Switching Mode
VOUT VIN
Note that VIN is limited to low voltages because the switches in the DAC ladder no longer have the same source-drain drive voltage. As a result, their on resistance differs and degrades the integral linearity of the DAC. Also, VIN must not go negative by more than 0.3 V, or an internal diode turns on, causing the device to exceed the maximum ratings. In this type of application, the full range of multiplying capability of the DAC is lost.
VDD R1
R2
GND +5V
VDD
C1
RFBA
8-/10-/12-BIT IOUTA DAC AGND
–2.5V
VREFA
VOUT = 0V to 2.5V
GND
–5V
NOTES 1. ADDITIONAL PINS OMITTED FOR CLARITY. 2. C1 PHASE COMPENSATION (1pF TO 2pF) MAY BE REQUIRED IF A1 IS A HIGH SPEED AMPLIFIER.
04462-034
Figure 40 shows the DACs operating in voltage-switching mode. The reference voltage, VIN, is applied to the IOUTA pin, and the output voltage is available at the VREFA terminal. In this configuration, a positive reference voltage results in a positive output voltage, making single-supply operation possible. The output from the DAC is voltage at constant impedance (the DAC ladder resistance). Therefore, an op amp is necessary to buffer the output voltage. The reference input no longer sees constant input impedance, but one that varies with code. Therefore, the voltage input should be driven from a low impedance source.
Figure 41. Positive Voltage Output with Minimum Components
ADDING GAIN In applications where the output voltage must be greater than VIN, gain can be added with an additional external amplifier, or it can be achieved in a single stage. Consider the effect of temperature coefficients of the thin film resistors of the DAC. Simply placing a resistor in series with the RFB resistor causes mismatches in the temperature coefficients, resulting in larger gain temperature coefficient errors. Instead, the circuit in Figure 42 shows the recommended method for increasing the gain of the circuit. R1, R2, and R3 should have similar temperature coefficients, but they need not match the temperature coefficients of the DAC. This approach is recommended in circuits where gains of greater than 1 are required.
RFBA VDD VIN
IOUTA
VREFA
VOUT
VDD
AGND GND
C1 R1 VIN 04462-033
NOTES 1. ADDITIONAL PINS OMITTED FOR CLARITY. 2. C1 PHASE COMPENSATION (1pF TO 2pF) MAY BE REQUIRED IF A1 IS A HIGH SPEED AMPLIFIER.
RFBA I
A
8-/10-/12-BIT OUT AGND VREFA DAC
VOUT R3
GND R2
GAIN =
R2 + R3 R2
R2R3 R1 = NOTES R2 + R3 1. ADDITIONAL PINS OMITTED FOR CLARITY. 2. C1 PHASE COMPENSATION (1pF TO 2pF) MAY BE REQUIRED IF A1 IS A HIGH SPEED AMPLIFIER.
Figure 40. Single-Supply Voltage-Switching Mode
Positive Output Voltage The output voltage polarity is opposite to the VREF polarity for dc reference voltages. To achieve a positive voltage output, an applied negative reference to the input of the DAC is preferred over the output inversion through an inverting amplifier because of the resistor’s tolerance errors. To generate a negative reference, the reference can be level-shifted by an op amp such that the VOUT and GND pins of the reference become the virtual ground and –2.5 V, respectively, as shown in Figure 41.
Rev. C | Page 19 of 32
Figure 42. Increasing Gain of Current Output DAC
04462-035
VDD
AD5428/AD5440/AD5447
Data Sheet
DIVIDER OR PROGRAMMABLE GAIN ELEMENT
REFERENCE SELECTION
Current-steering DACs are very flexible and lend themselves to many applications. If this type of DAC is connected as the feedback element of an op amp and RFBA is used as the input resistor, as shown in Figure 43, the output voltage is inversely proportional to the digital input fraction, D.
When selecting a reference for use with the AD54xx series of current output DACs, pay attention to the reference’s output voltage temperature coefficient specification. This parameter not only affects the full-scale error, but can also affect the linearity (INL and DNL) performance. The reference temperature coefficient should be consistent with the system accuracy specifications. For example, an 8-bit system required to hold its overall specification to within 1 LSB over the temperature range 0° to 50°C dictates that the maximum system drift with temperature should be less than 78 ppm/°C. A 12-bit system with the same temperature range to overall specification within 2 LSBs requires a maximum drift of 10 ppm/°C. Choosing a precision reference with low output temperature coefficient minimizes this error source. Table 9 lists some references available from Analog Devices that are suitable for use with these current output DACs.
For D = 1 − 2−n, the output voltage is VOUT = −V IN / D = −V IN /( 1 − 2 −n ) VDD VIN RFBA VDD IOUTA
VREFA
AGND GND
AMPLIFIER SELECTION
NOTES 1. ADDITIONAL PINS OMITTED FOR CLARITY.
04462-040
VOUT
Figure 43. Current-Steering DAC Used as a Divider or Programmable Gain Element
As D is reduced, the output voltage increases. For small values of the digital fraction D, it is important to ensure that the amplifier does not saturate and that the required accuracy is met. For example, an 8-bit DAC driven with the binary code 0x10 (0001 0000)—that is, 16 decimal—in the circuit of Figure 43 should cause the output voltage to be 16 times VIN. However, if the DAC has a linearity specification of ±0.5 LSB, D can have a weight in the range of 15.5/256 to 16.5/256 so that the possible output voltage is in the range of 15.5 VIN to 16.5 VIN— an error of 3%, even though the DAC itself has a maximum error of 0.2%. DAC leakage current is also a potential error source in divider circuits. The leakage current must be counterbalanced by an opposite current supplied from the op amp through the DAC. Because only a fraction, D, of the current into the VREF terminal is routed to the IOUT1 terminal, the output voltage changes as follows: Output Error Voltage Due to DAC Leakage = (Leakage × R )/ D
where R is the DAC resistance at the VREF terminal. For a DAC leakage current of 10 nA, R = 10 kΩ, and a gain (that is, 1/D) of 16, the error voltage is 1.6 mV.
The primary requirement for the current-steering mode is an amplifier with low input bias currents and low input offset voltage. Because of the code-dependent output resistance of the DAC, the input offset voltage of an op amp is multiplied by the variable gain of the circuit. A change in the noise gain between two adjacent digital fractions produces a step change in the output voltage due to the amplifier’s input offset voltage. This output voltage change is superimposed on the desired change in output between the two codes and gives rise to a differential linearity error, which, if large enough, could cause the DAC to be nonmonotonic. The input offset voltage should be <1/4 LSB to ensure monotonic behavior when stepping through codes. The input bias current of an op amp also generates an offset at the voltage output as a result of the bias current flowing in the feedback resistor, RFB. Most op amps have input bias currents low enough to prevent significant errors in 12-bit applications. Common-mode rejection of the op amp is important in voltageswitching circuits, because it produces a code-dependent error at the voltage output of the circuit. Most op amps have adequate common-mode rejection for use at 8-, 10-, and 12-bit resolution. Provided that the DAC switches are driven from true wideband, low impedance sources (VIN and AGND), they settle quickly. Consequently, the slew rate and settling time of a voltageswitching DAC circuit is determined largely by the output op amp. To obtain minimum settling time in this configuration, minimize capacitance at the VREF node (the voltage output node in this application) of the DAC by using low input capacitance buffer amplifiers and careful board design. Most single-supply circuits include ground as part of the analog signal range, which in turns requires an amplifier that can handle rail-to-rail signals. Analog Devices offers a wide variety of singlesupply amplifiers (see Table 10 and Table 11).
Rev. C | Page 20 of 32
Data Sheet
AD5428/AD5440/AD5447
Table 9. Suitable ADI Precision References Part No. ADR01 ADR01 ADR02 ADR02 ADR03 ADR03 ADR06 ADR06 ADR431 ADR435 ADR391 ADR395
Output Voltage (V) 10 10 5 5 2.5 2.5 3 3 2.5 5 2.5 5
Initial Tolerance (%) 0.05 0.05 0.06 0.06 0.10 0.10 0.10 0.10 0.04 0.04 0.16 0.10
Temp Drift (ppm/°C) 3 9 3 9 3 9 3 9 3 3 9 9
ISS (mA) 1 1 1 1 1 1 1 1 0.8 0.8 0.12 0.12
Output Noise (µV p-p) 20 20 10 10 6 6 10 10 3.5 8 5 8
Package SOIC-8 TSOT-23, SC70 SOIC-8 TSOT-23, SC70 SOIC-8 TSOT-23, SC70 SOIC-8 TSOT-23, SC70 SOIC-8 SOIC-8 TSOT-23 TSOT-23
Table 10. Suitable ADI Precision Op Amps Part No. OP97 OP1177 AD8551 AD8603 AD8628
Supply Voltage (V) ±2 to ±20 ±2.5 to ±15 2.7 to 5 1.8 to 6 2.7 to 6
VOS (Max) (µV) 25 60 5 50 5
IB (Max) (nA) 0.1 2 0.05 0.001 0.1
0.1 Hz to 10 Hz Noise (µV p-p) 0.5 0.4 1 2.3 0.5
Supply Current (µA) 600 500 975 50 850
Package SOIC-8 MSOP, SOIC-8 MSOP, SOIC-8 TSOT TSOT, SOIC-8
Table 11. Suitable ADI High Speed Op Amps Part No. AD8065 AD8021 AD8038 AD9631
Supply Voltage (V) 5 to 24 ±2.5 to ±12 3 to 12 ±3 to ±6
BW @ ACL (MHz) 145 490 350 320
Slew Rate (V/µs) 180 120 425 1,300
Rev. C | Page 21 of 32
VOS (Max) (µV) 1,500 1,000 3,000 10,000
IB (Max) (nA) 6,000 10,500 750 7,000
Package SOIC-8, SOT-23, MSOP SOIC-8, MSOP SOIC-8, SC70-5 SOIC-8
AD5428/AD5440/AD5447
Data Sheet
PARALLEL INTERFACE
8xC51-to-AD5428/AD5440/AD5447 Interface
Data is loaded into the AD5428/AD5440/AD5447 in 8-, 10-, or 12-bit parallel word format. Control lines CS and R/W allow data to be written to or read from the DAC register. A write event takes place when CS and R/W are brought low, data available on the data lines fills the shift register, and the rising edge of CS latches the data and transfers the latched data-word to the DAC register. The DAC latches are not transparent; therefore, a write sequence must consist of a falling and rising edge on CS to ensure that data is loaded into the DAC register and its analog equivalent is reflected on the DAC output.
Figure 45 shows the interface between the AD5428/AD5440/ AD5447 and the 8xC51 family of DSPs. To facilitate external data memory access, the address latch enable (ALE) mode is enabled. The low byte of the address is latched with this output pulse during access to the external memory. AD0 to AD7 are the multiplexed low order addresses and data bus, and they require strong internal pull-ups when emitting 1s. During access to external memory, A8 to A15 are the high order address bytes. Because these ports are open drain, they also require strong internal pull-ups when emitting 1s. A8 TO A15
A read event takes place when R/W is held high and CS is brought low. Data is loaded from the DAC register, goes back into the input register, and is output onto the data line, where it can be read back to the controller for verification or diagnostic purposes. The input and DAC registers of these devices are not transparent; therefore, a falling and rising edge of CS is required to load each data-word.
ADDRESS BUS
80511 ADDRESS DECODER
CS
WR
ALE
MICROPROCESSOR INTERFACING
AD5428/ AD5440/ AD54471
R/W DB0 TO DB11
8-BIT LATCH
ADSP-21xx-to-AD5428/AD5440/AD5447 Interface AD0 TO AD7
ADDR0 TO ADRR13
1ADDITIONAL
DMS
ADDRESS DECODER
CS
WR
PINS OMITTED FOR CLARITY.
Figure 45. 8xC51-to-AD5428/AD5440/AD5447 Interface
ADSP-BF5xx-to-AD5428/AD5440/AD5447 Interface Figure 46 shows a typical interface between the AD5428/ AD5440/AD5447 and the ADSP-BF5xx family of DSPs. The asynchronous memory write cycle of the processor drives the digital inputs of the DAC. The AMSx line is actually four memory select lines. Internal ADDR lines are decoded into AMS3–0, and then these lines are inserted as chip selects. The rest of the interface is a standard handshaking operation.
ADDRESS BUS
ADSP-21xx1
DATA BUS
04462-057
Figure 44 shows the AD5428/AD5440/AD5447 interfaced to the ADSP-21xx series of DSPs as a memory-mapped device. A single wait state may be necessary to interface the AD5428/ AD5440/AD5447 to the ADSP-21xx, depending on the clock speed of the DSP. The wait state can be programmed via the data memory wait state control register of the ADSP-21xx (see the ADSP-21xx family’s user manual for details).
AD5428/ AD5440/ AD54471
ADDR1 TO ADRR19
R/W
ADDRESS BUS
DB0 TO DB11
ADSP-BF5xx1
PINS OMITTED FOR CLARITY.
AMSx
ADDRESS DECODER
CS
AWE
R/W
Figure 44. ADSP21xx-to-AD5428/AD5440/AD5447 Interface
DB0 TO DB11
DATA 0 TO DATA 23 1ADDITIONAL
DATA BUS PINS OMITTED FOR CLARITY.
Figure 46. ADSP-BF5xx-to-AD5428/AD5440/AD5447 Interface
Rev. C | Page 22 of 32
04462-056
1ADDITIONAL
DATA BUS
04462-055
DATA 0 TO DATA 23
AD5428/ AD5440/ AD54471
Data Sheet
AD5428/AD5440/AD5447
PCB LAYOUT AND POWER SUPPLY DECOUPLING In any circuit where accuracy is important, careful consideration of the power supply and ground return layout helps to ensure the rated performance. The printed circuit board on which the AD5428/AD5440/AD5447 is mounted should be designed so that the analog and digital sections are separate and confined to certain areas of the board. If the DAC is in a system where multiple devices require an AGND-toDGND connection, the connection should be made at one point only. The star ground point should be established as close as possible to the device. These DACs should have ample supply bypassing of 10 μF in parallel with 0.1 μF on the supply located as close as possible to the package, ideally right up against the device. The 0.1 μF capacitor should have low effective series resistance (ESR) and low effective series inductance (ESI), like the common ceramic types of capacitors that provide a low impedance path to ground at high frequencies, to handle transient currents due to internal logic switching. Low ESR 1 μF to 10 μF tantalum or electrolytic capacitors should also be applied at the supplies to minimize transient disturbance and filter out low frequency ripple. Components, such as clocks, that produce fast-switching signals should be shielded with digital ground to avoid radiating noise to other parts of the board, and they should never be run near the reference inputs. Avoid crossover of digital and analog signals. Traces on opposite sides of the board should run at right angles to each other. This reduces the effects of feedthrough on the board. A
microstrip technique is by far the best method, but its use is not always possible with a double-sided board. In this technique, the component side of the board is dedicated to the ground plane, and signal traces are placed on the soldered side. It is good practice to use compact, minimum lead length PCB layout design. Leads to the input should be as short as possible to minimize IR drops and stray inductance. The PCB metal traces between VREF and RFB should also be matched to minimize gain error. To maximize high frequency performance, the I-to-V amplifier should be located as close as possible to the device.
EVALUATION BOARD FOR THE AD5447 The evaluation board consists of an AD5447 DAC and a current-to-voltage amplifier, the AD8065. Included on the evaluation board is a 10 V reference, the ADR01. An external reference may also be applied via an SMB input. The evaluation kit consists of a CD-ROM with self-installing PC software to control the DAC. The software simply allows the user to write a code to the device.
POWER SUPPLIES FOR THE EVALUATION BOARD The board requires ±12 V and +5 V supplies. The +12 V VDD and −12 V VSS are used to power the output amplifier; the +5 V is used to power the DAC (VDD1) and transceivers (VCC). Both supplies are decoupled to their respective ground plane with 10 μF tantalum and 0.1 μF ceramic capacitors.
Rev. C | Page 23 of 32
1 2 3 4 5 6 7 8 9 10 11 12
P1–7 P1–6 P1–5 P1–4 P1–3 P1–2
LEBA OEBA A0 A1 A2 A3 A4 A5 A6 A7 CEAB GND
C1 0.1μF
VDD1 C5 10μF
U4 VCC 24 CEBA B7 B6 B5 B4 B3 B2 B1 B0 LEAB OEAB
+
23 15 16 17 18 19 20 21 22 14 13
U1
C17 0.1μF
Rev. C | Page 24 of 32
Figure 47. Schematic of AD5447 Evaluation Board
DGND
P1–8 P1–9 P1–36
2 3 1
C2 0.1μF
U6-A Y0
A0 A1 E
Y1 Y2 Y3
5
1 2 3 4 5 6 7 8 9 10 11 12
7
LEBA OEBA A0 A1 A2 A3 A4 A5 A6 A7 CEAB GND
18 17 16 15 14 13 12 11 10 9 8 7 6 19 20
VCC CS RW
4
6
C6 0.1μF
AD5447 DB0 DB1 DB2 DB3 DB4 DB5 DB6 DB7 DB8 DB9 DB10 DB11
74ABT543
VCC
AD5428/AD5440/AD5447
VCC
U5 VCC 24
5
23 15 16 17 18 19 20 21 22
CEBA B7 B6 B5 B4 B3 B2 B1 B0 14 LEAB 13 OEAB
VDD DB0 DB1 DB2 DB3 DB4 RFBB DB5 IOUTB DB6 DB7 DB8 RFBA DB9 DB10 IOUTA DB11 DAC_A/B CS VREFA R/W VREFB DGND AGND
DGND
21 C23 10μF C22 1.8pF 23
+ VSS 2
24
3
U7
3 2
C26 0.1μF
4
C9 10μF J2
J5 EXT REF B
LK1 A
C7 1.8pF
+ VSS 2
3 +V IN
U3
+
C4 0.1μF
VDD
VOUT 4
U2
P1–31
B
VDD
C3 10μF
O/P B
+
22
3
74ABT543
J6
C25 10μF
VDD
1
J4
7
TP4
6
TP3 TP2
EXT REF A
J3
4 V– V+
C24 0.1μF
1
5 TRIM
C8 0.1μF
4 V– V+
7
C10 0.1μF
TP1 J1
6
O/P A
C11 10μF + C12 0.1μF
GND
2 P1–1 P1–14
U6-B 14 13
Y0 A0 A1
Y1 Y2
15 E DGND
11
P2–3
10 9
C13 0.1μF
+
C14 10μF
C15 0.1μF
+
C16 10μF
P2–2 AGND
P2–1 VSS
VDD1
P2–4
C17 0.1μF
+
C19 0.1μF
+
C18 10μF
VCC
P2–6
P2–5
C20 10μF
Data Sheet
04464-037
P1–19 P1–20 P1–21 P1–22 P1–23 P1–24 P1–25 P1–26 P1–27 P1–28 P1–29 P1–30
Y3
VDD
12
AD5428/AD5440/AD5447
04462-036
Data Sheet
04462-038
Figure 48. Component-Side Artwork
Figure 49. Silkscreen—Component-Side View (Top Layer)
Rev. C | Page 25 of 32
Data Sheet
04462-039
AD5428/AD5440/AD5447
Figure 50. Solder-Side Artwork
Rev. C | Page 26 of 32
Data Sheet
AD5428/AD5440/AD5447
BILL OF MATERIALS Table 12. Name/Position C1 C2 C3 C4 C5 C6 C7 C8 C9 C10 C11 C12 C13 C14 C15 C16 C17 C18 C19 C20 C21 C22 C23 C24 C25 C26 CS, DB0 to DB11 J1 to J6 J2 J3 J4 J5 J6 LK1 P1 P2 RW TP1 to TP4 U1 U2 U3 U4, U5 U6 U7 Each Corner
Part Description X7R ceramic capacitor X7R ceramic capacitor Tantalum capacitor—Taj series X7R ceramic capacitor Tantalum capacitor—Taj series X7R ceramic capacitor NPO ceramic capacitor X7R ceramic capacitor Tantalum capacitor—Taj series X7R ceramic capacitor Tantalum capacitor—Taj series X7R ceramic capacitor X7R ceramic capacitor Tantalum capacitor—Taj series X7R ceramic capacitor Tantalum capacitor—Taj series X7R ceramic capacitor Tantalum capacitor—Taj series X7R ceramic capacitor Tantalum capacitor—Taj series X7R ceramic capacitor NPO ceramic capacitor Tantalum capacitor—Taj series X7R ceramic capacitor Tantalum capacitor—Taj series X7R ceramic capacitor Red testpoint SMB socket SMB socket SMB socket SMB socket SMB socket SMB socket 3-pin header (2 × 2) 36-pin Centronics connector 6-pin terminal block Red testpoint Red testpoint AD5447 ADR01 AD8065 74ABT543 74139 AD8065 Rubber stick-on feet
Value 0.1 μF 0.1 μF 10 μF 20 V 0.1 μF 10 μF 10 V 0.1 μF 1.8 pF 0.1 μF 10 μF 20 V 0.1 μF 10 μF 20 V 0.1 μF 0.1 μF 10 μF 20 V 0.1 μF 10 μF 20 V 0.1 μF 10 μF 20 V 0.1 μF 10 μF 20 V 0.1 μF 1.8 pF 10 μF 20 V 0.1 μF 10 μF 20 V 0.1 μF
Rev. C | Page 27 of 32
Tolerance (%) 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10
Stock Code FEC 499-675 FEC 499-675 FEC 197-427 FEC 499-675 FEC 197-130 FEC 499-675 FEC 721-876 FEC 499-675 FEC 197-427 FEC 499-675 FEC 197-427 FEC 499-675 FEC 499-675 FEC 197-427 FEC 499-675 FEC 197-427 FEC 499-675 FEC 197-427 FEC 499-675 FEC 197-427 FEC 499-675 FEC 721-876 FEC 197-427 FEC 499-675 FEC 197-427 FEC 499-675 FEC 240-345 (Pack) FEC 310-682 FEC 310-682 FEC 310-682 FEC 310-682 FEC 310-682 FEC 310-682 FEC 511-791 and FEC 528-456 FEC 147-753 FEC 151-792 FEC 240-345 (Pack) FEC 240-345 (Pack) AD5447YRU ADR01AR AD8065AR Fairchild 74ABT543CMTC CD74HCT139M AD8065AR FEC 148-922
AD5428/AD5440/AD5447
Data Sheet
OVERVIEW OF AD54xx DEVICES Table 13. Part No. AD5424 AD5426 AD5428 AD5429 AD5450 AD5432 AD5433 AD5439 AD5440 AD5451 AD5443 AD5444 AD5415 AD5405 AD5445 AD5447 AD5449 AD5452 AD5446 AD5453 AD5553 AD5556 AD5555 AD5557 AD5543 AD5546 AD5545 AD5547 1
Resolution 8 8 8 8 8 10 10 10 10 10 12 12 12 12 12 12 12 12 14 14 14 14 14 14 16 16 16 16
No. DACs 1 1 2 2 1 1 1 2 2 1 1 1 2 2 2 2 2 1 1 1 1 1 2 2 1 1 2 2
INL (LSB) ±0.25 ±0.25 ±0.25 ±0.25 ±0.25 ±0.5 ±0.5 ±0.5 ±0.5 ±0.25 ±1 ±0.5 ±1 ±1 ±1 ±1 ±1 ±0.5 ±1 ±2 ±1 ±1 ±1 ±1 ±2 ±2 ±2 ±2
Interface Parallel Serial Parallel Serial Serial Serial Parallel Serial Parallel Serial Serial Serial Serial Parallel Parallel Parallel Serial Serial Serial Serial Serial Parallel Serial Parallel Serial Parallel Serial Parallel
Package1 RU-16, CP-20 RM-10 RU-20 RU-10 UJ-8 RM-10 RU-20, CP-20 RU-16 RU-24 UJ-8 RM-10 RM-8 RU-24 CP-40 RU-20, CP-20 RU-24 RU-16 UJ-8, RM-8 RM-8 UJ-8, RM-8 RM-8 RU-28 RM-8 RU-38 RM-8 RU-28 RU-16 RU-38
RU = TSSOP, CP = LFCSP, RM = MSOP, UJ = TSOT.
Rev. C | Page 28 of 32
Features 10 MHz BW, 17 ns CS pulse width 10 MHz BW, 50 MHz serial 10 MHz BW, 17 ns CS pulse width 10 MHz BW, 50 MHz serial 10 MHz BW, 50 MHz serial 10 MHz BW, 50 MHz serial 10 MHz BW, 17 ns CS pulse width 10 MHz BW, 50 MHz serial 10 MHz BW, 17 ns CS pulse width 10 MHz BW, 50 MHz serial 10 MHz BW, 50 MHz serial 10 MHz BW, 50 MHz serial 10 MHz BW, 50 MHz serial 10 MHz BW, 17 ns CS pulse width 10 MHz BW, 17 ns CS pulse width 10 MHz BW, 17 ns CS pulse width 10 MHz BW, 50 MHz serial 10 MHz BW, 50 MHz serial 10 MHz BW, 50 MHz serial 10 MHz BW, 50 MHz serial 4 MHz BW, 50 MHz serial clock 4 MHz BW, 20 ns WR pulse width 4 MHz BW, 50 MHz serial clock 4 MHz BW, 20 ns WR pulse width 4 MHz BW, 50 MHz serial clock 4 MHz BW, 20 ns WR pulse width 4 MHz BW, 50 MHz serial clock 4 MHz BW, 20 ns WR pulse width
Data Sheet
AD5428/AD5440/AD5447
OUTLINE DIMENSIONS 7.90 7.80 7.70
6.60 6.50 6.40 24 20
13
4.50 4.40 4.30
11
4.50 4.40 4.30
6.40 BSC 1
12
6.40 BSC 1
PIN 1
10
0.65 BSC
PIN 1 0.65 BSC 1.20 MAX
0.15 0.05 COPLANARITY 0.10
0.30 0.19
0.15 0.05
0.20 0.09
SEATING PLANE
8° 0°
0.75 0.60 0.45
0.30 0.19
1.20 MAX
SEATING PLANE
0.20 0.09
8° 0°
0.75 0.60 0.45
0.10 COPLANARITY
COMPLIANT TO JEDEC STANDARDS MO-153-AC
COMPLIANT TO JEDEC STANDARDS MO-153-AD
Figure 51. 20-Lead Thin Shrink Outline Package [TSSOP] (RU-20) Dimensions shown in millimeters
Figure 52. 24-Lead Thin Shrink Small Outline Package [TSSOP] (RU-24) Dimensions shown in millimeters
ORDERING GUIDE Model1 AD5428YRU AD5428YRU-REEL AD5428YRU-REEL7 AD5428YRUZ AD5428YRUZ-REEL AD5428YRUZ-REEL7 AD5440YRU AD5440YRU-REEL AD5440YRU-REEL7 AD5440YRUZ AD5440YRUZ-REEL AD5440YRUZ-REEL7 AD5447YRU AD5447YRU-REEL AD5447YRUZ AD5447YRUZ-REEL AD5447YRUZ-REEL7 EVAL-AD5447EBZ 1
Resolution 8 8 8 8 8 8 10 10 10 10 12 12 12 12 12 12 12
INL (LSB) ±0.5 ±0.5 ±0.5 ±0.5 ±0.5 ±0.5 ±0.5 ±0.5 ±0.5 ±0.5 ±1 ±1 ±1 ±1 ±1 ±1 ±1
Temperature Range –40 °C to +125°C –40 °C to +125°C –40 °C to +125°C –40 °C to +125°C –40 °C to +125°C –40 °C to +125°C –40 °C to +125°C –40 °C to +125°C –40 °C to +125°C –40 °C to +125°C –40 °C to +125°C –40 °C to +125°C –40 °C to +125°C –40 °C to +125°C –40 °C to +125°C –40 °C to +125°C –40 °C to +125°C
Z = RoHS Compliant Part.
Rev. C | Page 29 of 32
Package Description 20-Lead TSSOP 20-Lead TSSOP 20-Lead TSSOP 20-Lead TSSOP 20-Lead TSSOP 20-Lead TSSOP 24-Lead TSSOP 24-Lead TSSOP 24-Lead TSSOP 24-Lead TSSOP 24-Lead TSSOP 24-Lead TSSOP 24-Lead TSSOP 24-Lead TSSOP 24-Lead TSSOP 24-Lead TSSOP 24-Lead TSSOP Evaluation Kit
Package Option RU-20 RU-20 RU-20 RU-20 RU-20 RU-20 RU-24 RU-24 RU-24 RU-24 RU-24 RU-24 RU-24 RU-24 RU-24 RU-24 RU-24
AD5428/AD5440/AD5447
Data Sheet
NOTES
Rev. C | Page 30 of 32
Data Sheet
AD5428/AD5440/AD5447
NOTES
Rev. C | Page 31 of 32
AD5428/AD5440/AD5447
Data Sheet
NOTES
©2004–2011 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D04462-0-8/11(C)
Rev. C | Page 32 of 32
