Transcript
M3TEK
MT3123/MT3123A
Preliminary Datasheet
5V 4A 1.25MHz 15µA Low Iq FAST-PWM Synchronous Step-Down Converter
DESCRIPTION
FEATURES
The MT3123/MT3123A is a 4A high efficiency
Wide Input Range from 2.5V to 6V
High Efficiency up to 97%
Output Voltage as low as 0.6V
100% Duty Cycle Operation
2.5V to 6V and provide output range from 0.6V to
+/-1.5% 0.6V Feedback Voltage Accuracy
as high as input level, thanks to its 100% duty cycle
1.25MHz Pseudo Constant Switching Frequency
operation. Its advanced constant on-time control
15µA Quiescent Current
Continuous Output Current up to 4A
Built-in 48mΩ HS and 38mΩ LS Power Switches
Cycle-by-cycle Current Limit Protection
Hiccup Mode for Short Circuit and Over-Load
constant on-time controlled synchronous stepdown converter. It operates with input voltage from
Fast-PWM scheme simplifies loop compensation and offers excellent load transient response while maintaining
a
relatively
constant
1.25MHz
switching frequency. MT3123/MT3123A consumes
Protection
extremely low 15µA quiescent current hence
Open Drain Power Good Indication with Internal Pullup Resistor
achieves superior light load efficiency. The high
Thermal Shutdown Protection
Stable with low ESR ceramic Output Capacitors
excellent load and line regulation. For fault tolerant
Available in a Small QFN3x3mm_16L Package
operation, MT3123/MT3123A has cycle-by-cycle
Pb-Free RoHS Compliant
gain error amplifier in the control loop provides
current limit protection and hiccup mode for short
APPLICATIONS
circuit or over-load condition. MT3123/MT3123A is available in QFN3x3mm
Solid-State and Hard Disk Drives
Portable / Handheld Devices
package and ideal for high performance, portable
WiFi Moudule, Set-top Boxes
applications.
DC/DC Micro Modules
TYPICAL APPLICATIONS VIN 2.5V~5.5V PVIN1 PVIN2
SW1 SW2
10R
CIN 22uF
VOUT 3.3V
L 1uH
COUT 10uFx2
AVIN
Efficiency
95% 90%
0.1uF PG
100%
PG
MT3123 MT3123A
OUT R1 196K
SS*
85% 5Vin 3.3Vo 5Vin 2.5Vo 5Vin 1.8Vo 5Vin 1.2Vo
CFF
Option
80%
FB 10K EN
EN 0.1uF
*Option for MT3123A
Rev. 0.4 www.m3tekic.com
PGND1 AGND PGND2
R2 43.2K
75% 70% 0.001
0.01
0.1
1
Iout (A)
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M3TEK
MT3123/MT3123A
Preliminary Datasheet
5V 4A 1.25MHz 15µA Low Iq FAST-PWM Synchronous Step-Down Converter
Ordering Information Part No.
Marking
Temp. Range
Package
MOQ
MT3123NQAR
MT3123 YWWxx
-40°C ~ 85°C
QFN3X3_16L
5,000/Reel
MT3123AQAR
3123A YWWxx
-40°C ~ 85°C
QFN3X3_16L
5,000/Reel
Note: Y: Year, WW: Week
PGND
EN
EN
OUT
PGND
PGND
PGND
13
13
14
14
15
15
16
16
OUT
PIN CONFIGURATION
SW
1
12
PVIN
SW
1
12
PVIN
SW
2
11
PVIN
SW
2
11
PVIN
10
AVIN
9
SS
9
NC
PG
4
NC
NC
NC
FB
NC
8
3
7
NC
6
AVIN
5
10
EP
AGND
AGND
FB
8
4 7
PG
6
3
5
NC
EP
MT3123
MT3123A QFN3x3_16L TOP VIEW
Pin Description PIN NAME
MT3123 PIN NO.
MT3123A PIN NO.
SW
1, 2
1, 2
NC
3, 7, 8, 9
3, 7, 8
PG
4
4
Open-drain power good indication.
FB
5
5
Feedback voltage input, connect to external feedback resistors
AGND
6
6
Analog ground
SS
-
9
Soft-start programming pin. Do not float this pin. Connect a capacitor from this pin to ground to program the soft-start time. TSS=Max(CSS×0.6V/1.6μA, 60μs)
AVIN
10
10
Analog Input supply voltage
PVIN
11, 12
11, 12
Power Input supply voltage
PGND
14, 15, EP
14, 15, EP
EN
13
13
Enable input, Integrated 1MΩ pull down resistor.
OUT
16
16
Output voltage sense
Rev. 0.4 www.m3tekic.com
DESCRIPTION Switching pin, connect to external inductor No connection, Leave float
Power ground
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M3TEK
Preliminary Datasheet
MT3123/MT3123A
5V 4A 1.25MHz 15µA Low Iq FAST-PWM Synchronous Step-Down Converter
Absolute Maximum Rating (Reference to GND) (Note1) SW to PGND …..…………….....……......… -0.5V to VOUT+1V
ESD …………………………………………...……….. Class 2
VIN/PVIN to AGND ……..………….....………….. -0.3V to 6V
Lead Temperature( Soldering 10s) ……………..…… 260°C
PGND to AGND …………………………………. -0.3V to 0.3V
Junction Temperature Range …………..….. -40°C to 150°C
EN, OUT, FB, PGOOD to AGND ..……….……... -0.3V to 6V
Storage Temperature Range …………........ -65°C to 150°C
Recommend Operating Conditions (Note2) Input Voltage (VBAT) …………..…….…..……… +2.4V to 5.5V
Operating Temperature Range …………..….. -40°C to 85°C
Output Voltage (VOUT) ………..………..………… +0.6V to VIN
Junction Temperature Range, TJ ………...…..……. <.135°C
Thermal information (Note3, 4) Maximum Power Dissipation (TA=25°C) QFN3x3_16 ..... 2W
Thermal Resistance (θJA) QFN ………...…..………. 50°C/W Thermal Resistance (θJC) QFN ………...….....……. 7.8°C/W
Note(1): Stress exceeding those listed “Absolute Maximum Ratings” may damage the device. Note(2): The device is not guaranteed to function outside of the recommended operating conditions. Note(3): Measured on JESD51-7, 4-Layer PCB. Note(4): The maximum allowable power dissipation is a function of the maximum junction temperature T J_MAX, the junction to ambient thermal resistance θJA, and the ambient temperature TA. The maximum allowable continuous power dissipation at any ambient temperature is calculated by PD_MAX= (TJ_MAX-TA)/θJA. Exceeding the maximum allowable power dissipation will cause excessive die temperature, and the regulator will go into thermal shutdown. Internal thermal shutdown circuitry protects the device from permanent damage.
Electrical Characteristics TA = 25°C, VIN=5V, unless otherwise noted. PARAMETER
TEST CONDITIONS
Input Voltage Range VIN Shutdown Current Input Under Voltage Lockout Threshold
MIN
VEN = 0V, VIN = 5.5V VIN Increasing
2.3
Input Under Voltage Lockout Hysteresys Quiescent Current IQ
MAX
UNIT
6
V
0.1
1
µA
2.4
2.5
V
250 VFB = 0.63V, OUT float
Feedback Voltage VFB
591
Feedback Current IFB Oscillator Frequency
TYP
2.5
IOUT=500mA
18
µA
600
609
mV
1
nA
1.25
MHz
HS Switch Current Limit
5
HS Switch On Resistance
48
LS Switch On Resistance
mV
15
6
A mΩ mΩ
38
HS Leakage Current
VIN = 5.5V, VEN = VSW = 0V
0.1
1
µA
LS Leakage Current
VIN = VSW = 5.5V, VEN = 0V
0.1
1
µA
VIN = 5V, VOUT = 1.2V
200
ns
VIN = 5V, VOUT = 3.3V
530
ns
VFB =0.5V, sink 1mA
0.2
V
VFB = 0.63V , VPGOOD = VIN = 5.5V
10
nA
On-time for HS Switch PGOOD Output Low Voltage PGOOD Output Leakage Current
Rev. 0.4 www.m3tekic.com
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M3TEK
MT3123/MT3123A
Preliminary Datasheet
5V 4A 1.25MHz 15µA Low Iq FAST-PWM Synchronous Step-Down Converter
PARAMETER PGOOD Over Voltage Rise Threshold PGOOD Over Voltage Fall Threshold
TEST CONDITIONS
MIN
TYP
MAX
UNIT
VFB with ramp from over voltage
+8
+10
+12
%
VFB ramp up from regulation
PGOOD Under Voltage Rise Threshold
+15
VFB with ramp up from under voltage
PGOOD Under Voltage Fall Threshold PGOOD Delay
-12
-10
% -8
%
VFB ramp down from regulation
-15
%
PGOOD going High to Low
25
µs
PGOOD Pull-up resistor
0.8
EN On Threshold
1.0
1
0.8
Internal Soft Start Time, MT3123
MΩ V
EN Off Threshold EN Internal Pull Down Resistor
1.2
1
0.5
V
1.2
MΩ
600
µs
TSS=Max(CSS×0.6V/1.6μA, 60μs)
1.6
µA
CSS=1nF
400
µs
Thermal Shutdown
160
℃
Thermal Shutdown Hysteresis
30
℃
Soft Start Current, MT3123A Soft Start Time, MT3123A
Functional Block Diagram
AIN
PVIN
V060 VREFSS
EA VREFSS
FB
ON
TON
Constant On-time Modulation Ramp
VIN
HSON Control Logic
VIN
SW LSON
OUT
VOUT
ILIMT
EN AIN 0.66V UVLO 0.60V & Bandgap 0.54V
PG
V066 V060 V054
ILIMT
0.66V
Current Limit & Over-load Detection
OVLD VFB
0.54V < FB < 0.66V
Soft-Start
VREFSS
0.54V
AGND
Rev. 0.4 www.m3tekic.com
PGND
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M3TEK
MT3123/MT3123A
Preliminary Datasheet
5V 4A 1.25MHz 15µA Low Iq FAST-PWM Synchronous Step-Down Converter
TYPICAL PERFORMANCE CHARACTERISTICS (CIN=10uF, COUT = 10uFx2, L=1uH, TA =25 ℃) Steady State Test
Steady State Test
Load Transient Response
Vin=5V, Vout=1.2V, Iout=0A
Vin=5V, Vout=1.2V, Iout=3.5A
Vin=5V, Vout=1.2V, Iout=1.5A to 3A
CH1:SW
CH2:VOUT CH3:VIN
CH4:IL
CH1:SW
CH2:VOUT CH3:VIN
CH4:IL
CH1:VOUT CH2:IL
Vin Power On
Vin Power Off
EN On
Vin=5V, Vout=1.2V, Iout=0A
Vin=5V, Vout=1.2V, Iout=0A
Vin=5V, Vout=1.2V, Iout=0A
CH1:SW
CH2:VOUT CH3:VIN
CH4:IL
CH1:SW
CH2:VOUT CH3:VIN
CH4:IL
CH1:SW
CH2:VOUT CH3:EN CH4:IL
Vin Power On
Vin Power On
EN Off
Vin=5V, Vout=1.2V, Iout=3.5A
Vin=5V, Vout=1.2V, Iout=3.5A
Vin=5V, Vout=1.2V, Iout=0A
CH1:SW
CH2:VOUT CH3:VIN
Rev. 0.4 www.m3tekic.com
CH4:IL
CH1:SW
CH2:VOUT CH3:VIN
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CH4:IL
CH1:SW
CH2:VOUT CH3:EN CH4:IL
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M3TEK
MT3123/MT3123A
Preliminary Datasheet
5V 4A 1.25MHz 15µA Low Iq FAST-PWM Synchronous Step-Down Converter
TYPICAL PERFORMANCE CHARACTERISTICS (CIN=10uF, COUT = 10uFx2, L=1uH, TA =25 ℃) EN On
EN Off
Vin=5V, Vout=1.2V, Iout=3.5A
Vin=5V, Vout=1.2V, Iout=3.5A
CH1:SW
CH1:SW
CH2:VOUT CH3:EN CH4:IL
Short Circuit Entry
Short Circuit Recovery
Vin=5V, Vout=1.2V, Iout=0A
Vin=5V, Vout=1.2V, Iout=0A
CH1:SW
Rev. 0.4 www.m3tekic.com
CH2:VOUT CH3:EN CH4:IL
CH2:VOUT CH3:VIN
CH4:IL
CH1:SW
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CH2:VOUT CH3:VIN
CH4:IL
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M3TEK
Preliminary Datasheet
MT3123/MT3123A
5V 4A 1.25MHz 15µA Low Iq FAST-PWM Synchronous Step-Down Converter
OPERATION MT3123/MT3123A is a constant on-time controlled synchronous step-down converter that offers excellent transient response over a wide range of input voltage. It achieves superior light-load efficiency with extremely low quiescent current.
FAST-PWM CONSTANT ON-TIME CONTROL MT3123/MT3123A employs advanced constant on-time control (Fast-PWM) to achieve superior transient response. The Fast-PWM constant on-time control turns on HS immediately when FB droops below reference. The HS is turned on for a pre-determined period (on-time) to ramp up the inductor current, and then the LS will be turned on to ramp down the inductor current. The cycle repeats itself if FB droops below reference again. MT3123/MT3123A uses adaptive on-time based on input and output voltage level to achieve a relatively constant switching frequency. The on-time can be estimated as:
TON =
VOUT ∙ 0.833μ VIN
Due to its immediate response on FB voltage droop and simplified loop compensation, Fast-PWM constant on-time offers a superior transient response compare to traditional fixed frequency PWM control step-down converters.
LIGHT LOAD OPERATION In light load condition where the switcher operates in discontinuous mode, MT3123/MT3123A cuts down its quiescent current to as low as 15uA, thus achieve excellent light load efficiency.
ENABLE When input voltage is above the under voltage lock-out threshold, MT3123/MT3123A can be enabled by pulling the EN pin to above 1V. MT3123/MT3123A will be disabled if the EN pin is kept below 0.5V.
SOFT START MT3123 has built-in 600µs soft-start timer. During the soft start period, output voltage is ramped up linearly to the regulation voltage, independent of the load current level and output capacitor value. MT3123A provides an external soft-start pin that gradually raises the output voltage. The soft-start time can be programmed by the external capacitor across SS pin and GND. The chip provides a 1.6μA charge current for the external capacitor, It is not recommended to leave SS pin, The soft start time is calculated as:
TSS = Max (
CSS ∙0.6V 1.6μ𝐴
, 60μs )
CURRENT LIMIT and HICCUP MODE MT3123/MT3123A has cycle-by-cycle HS current limit protection to prevent inductor current from running away. Once HS current limit is triggered, MT3123/MT3123A will turn on LS and wait for the inductor to drop down to a pre-determined level before the HS can be turned on again. If this current limit condition is repeated for a sustained long period of time, MT3123/MT3123A will consider it as over-load or short circuit. Either way, MT3123/MT3123A will enter hiccup mode, where it stop switching for a pre-determined period of time before automatically re-try to start up again. It always starts up with soft-start to limit inrush current and avoid output overshoot.
Rev. 0.4 www.m3tekic.com
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M3TEK
Preliminary Datasheet
MT3123/MT3123A
5V 4A 1.25MHz 15µA Low Iq FAST-PWM Synchronous Step-Down Converter
POWER GOOD INDICATION MT3123/MT3123A has open drain PGOOD indicator with internal 1MΩ pull-up resistor to input voltage. PGOOD will be pulled up if output voltage is within +/-10% of regulation, otherwise PGOOD is pulled down by the internal NMOS.
APPLICATION INFORMATION Setting the Output Voltage External feedback resistors are used to set the output voltage. Refer to typical application circuit on page 1, the top feedback resistor R2 has some impact on the loop stability, so its recommended range is below 100kΩ. For any chosen R2, the bottom feedback resistor R1 can be calculated as:
R1 VOUT VOUT = VREF ∙ ( + 1) , thus R1 = R 2 ∙ ( − 1) R2 0.6 Inductor Selection The recommended inductor value for MT3123/MT3123A is between 0.68uH to 4.7uH. Usually the inductor value is chosen to satisfy a desired ripple current:
L=
VOUT ∙ (VIN − VOUT ) VIN ∙ fSW ∙ ∆I
Where ∆𝐼 is the inductor ripple current. With the chosen ∆𝐼, the peak inductor current will be:
IPK = ILOAD +
1 ∙ ∆I 2
Input Bypass Capacitor Selection The input current to the step-down converter is discontinuous with very sharp edges, therefore an input bypass capacitor is required. For best performance, it’s recommended to use low ESR ceramic capacitors and place them as close to the input pin as possible. For lowest temperature variations, use X5R or X7R dielectric ceramic capacitors. The RMS current of the input capacitor is approximately:
ICIN_RMS = IOUT √D(1 − D) From the equation, it can be seen that the highest RMS current occurs when D is 0.5:
1 ICIN_RMS = IOUT 2 Choose the capacitor with RMS current rating higher than 1/2 I OUT, The power dissipation on the input capacitor can be estimated with the RMS current and the ESR resistor. Electrolytic or tantalum capacitors can also be used, but due to their significantly higher ESR, a small size ceramic capacitor should be placed as close to the IC as possible. The voltage ripple on the input capacitor, neglecting the ESR impact, can be calculated as:
∆VCIN =
Rev. 0.4 www.m3tekic.com
ILOAD VOUT VOUT ∙ ∙ (1 − ) fSW ∙ CIN VIN VIN
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M3TEK
MT3123/MT3123A
Preliminary Datasheet
5V 4A 1.25MHz 15µA Low Iq FAST-PWM Synchronous Step-Down Converter
Output Capacitor Selection An output capacitor is required to obtain a stable output voltage. To minimize the output voltage ripple, ceramic capacitors should be used, and the ripple voltage can be estimated as:
∆VOUT =
1 VOUT VOUT 1 ∙ (1 − )∙ ∙ 2 8 VIN L (fSW ) ∙ COUT
If electrolytic or tantalum capacitors are used, the ESR will dominate the output voltage ripple:
∆𝑉𝑂𝑈𝑇 = (1 −
𝑉𝑂𝑈𝑇 𝑉𝑂𝑈𝑇 )∙ ∙𝑅 𝑉𝐼𝑁 𝑓𝑆𝑊 ∙ 𝐿 𝐸𝑆𝑅
AVIN Bypass Cap Recommend a R-C filter 10Ω and 0.1uF for AVIN when IOUT >3A.
VIN 2.5V~5.5V
VOUT 1.2V
L PVIN1 PVIN2
CIN
SW1 SW2
VIN 2.5V~5.5V
L
1uH 10R
CIN
PVIN1 PVIN2
SW1 SW2
AVIN
OUT
1uH
COUT 0.1uF
PG
R2 100k
EN 0.1uF
AGND
PGND1 PGND2
R1 100k
MT3123 PG
FB
10K EN
0.1uF R1 100k
MT3123 PG
COUT
OUT
AVIN
VOUT 1.2V
PG
FB
10K
R2 100k
EN
EN 0.1uF
Iout < 3A
AGND
PGND1 PGND2
Iout > 3A
PCB Layout Recommendation Proper layout and component placement are very important, and sometimes critical for the step-down converters. The PCB can radiate excessive noise and contribute to converter instability with improper layout. Certain points must be considered before starting a layout using the MT3123/MT3123A.
Use wide trace for the high current paths, the traces of the high current paths as short and wide as possible.
Place the input capacitor CIN close to pin11,12 (PVIN) and pin14,15 (PGND), so the total PCM trace from the pins to CIN capacitor is minimized.
SW pin and the trace will be the most noisy signal on the board, so proper isolation between SW from FB is essential, SW node encounters high frequency voltage swings so it should be kept in a small area.
Ensure all feedback network connections are short and direct. Place the feedback network as close to the chip as possible.
Components away from the SW node to prevent stray capacitive noise pick-up.
The GND pin and Exposed Pad should be connected to a strong ground plane for heat sinking and noise protection.
An example of PCB layout guide is shown in below Figure for reference.
Rev. 0.4 www.m3tekic.com
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M3TEK
MT3123/MT3123A
Preliminary Datasheet
5V 4A 1.25MHz 15µA Low Iq FAST-PWM Synchronous Step-Down Converter
PACKAGING INFORMATION QFN 16L 3mmx3mm PACKAGE OUTLINE DIMENSIONS
D
D1 L e E1
E
b DETAIL A A A1
SYMBOLS
INCHES
MIN.
MAX.
MIN.
MAX.
A
0.70
0.80
0.028
0.031
A1
0.00
0.05
0.000
0.002
b
0.18
0.30
0.007
0.012
E
2.90
3.10
0.114
0.122
D
2.90
3.10
0.114
0.122
D1
1.70
0.067
E1
1.70
0.067
e
0.50
0.020
L
Rev. 0.4 www.m3tekic.com
MILLIMETERS
0.30
0.50
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0.012
0.020
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M3TEK
MT3123/MT3123A
Preliminary Datasheet
5V 4A 1.25MHz 15µA Low Iq FAST-PWM Synchronous Step-Down Converter
Carrier Tape & Reel Dimensions 1. Orientation / Carrier Tape Information :
B
A
C
D
Feeding direction
2. Rokreel Information :
3. Dimension Details :
PKG Type
A
B
C
D
E
F
Q'ty/Reel
Q(D)FN 3x3
4.0 mm
1.5 mm
12.0 mm
8.0 mm
13 inches
13.0 mm
5,000
Rev. 0.4 www.m3tekic.com
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M3TEK
MT3123/MT3123A
Preliminary Datasheet
5V 4A 1.25MHz 15µA Low Iq FAST-PWM Synchronous Step-Down Converter
Reflow Profile Classification Of IR Reflow Profile Reflow Profile
Green Assembly
Average Ramp-Up Rate (Tsmin to Tp)
1~2℃/second, 3℃/second max.
Preheat & Soak -Temperature Min(Tsmin) -Temperature Max(Tsmax) -Time(tsmin to ts tsmax) Time maintained above: -Temperature(TL) -Time(tL)
150℃ 200℃ 60~120 seconds 217℃ 60~150 seconds
Peak Temperature(Tp)
See Classification Temp in table 1
Time within 5℃ of actual Peak Temperature(tp)
30 seconds max.
Ramp-Down Rate
6℃/second max.
Time 25℃ to Peak Temperature
8 minutes max.
* Tolerance for peak profile Temperature (Tp) is defined as a supplier minimum and a user maximum. ** Tolerance for time at peak profile temperature (tp) is defined as a supplier minimum and a user maximum. Table 1. Pb-free Process – Classification Temperatures (Tc) 3 Volume mm Package Thickness <350
Volume mm 350-2000
3
Volume mm >2000
<1.6 mm
260 ℃
260 ℃
260 ℃
1.6 mm – 2.5 mm
260 ℃
250 ℃
245 ℃
2.5 mm
250 ℃
245 ℃
245 ℃
3
Note: For all temperature information, please refer to topside of the package, measured on the package body surface.
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