Transcript
Renesas Continuous Conduction Mode PFC IC
R2A20115
Rev.6.0 April 2010
with High Accurate Constant Power Limiter
Features • No reference voltage adjustment resistor is needed with higher accurate built-in circuit (+/-1.6%) than previous products (+/-2%). • No margin for inductor design is needed with higher accuracy of detect level of the built-in over current protection circuit. (Previously, the margin can not be omitted for its lower accuracy) • Prevention of “coil vibration” at starting-up or over current period by the function of VCC OUT power limiter. (Previously, it’s not supported) SS GND DIP16 • The function of power limiter cuts down unnecessary power supplied to the next EO DELAY stage. (Previously, the higher AC input voltage is applied, the higher power can be FB CGND or supplied to the next stage, of which power supply might be heavily loaded unnecessarily.) IAC CAI • Prevention of overshoot on output voltage by dynamic OVP function without specific VREF SOP16 PFC-ON Pins. (Previously, this function is not supported or partly supported using specific Pins) CT CAO • Power dissipation is cut down by 35% of comparable products. RT CLIMIT • Easy system design by using calculation sheet in Excel format provided for customers.
1-1. Introduction of Constant Power Limiter Using Current Monitoring and Setting Pins Separately
Voltage amplifier FB Constant power limiter EO
Multiplier
CS
Input Ef f ectiv e Power v s Input AC Voltage
R2A20115
Multiplier
CAI
Current amplifier Over-current limiter
Current amplifier
VREF
Input Effective Power [W]
Conventional
1-2. Introduction of Constant Power Limiter and Reduction of Needless Device Margin by the Improvement of it’s Accuracy 6000 5000
R2A20115 [W] [W] 有効電力(R2A20115)
4000
Using only Over Current Limiter (calculated) [W] 過電流検出のみ電力制限(計算値)
3000 2000 1000 0
CLIMIT Over-current limiter
0
“Coil vibration” is prevented by gradual/steady control when over current occurs.
50
100
150 200 250 Input AC v oltage [V]
Constant power limiter is effectively working independently of input voltage
300
1-3. Reduction of Maximum Current in Boost Inductor by Improved Accuracy of Power Limiter and Current Limiter R2A20111
Input AC Current
Current Limiter
Current limiter accuracy
Cut the extra margin by minimizing the peak current distribution of inductor due to high accuracy power limiter and current limiter function.
R2A20115
Input AC Current
Current Limiter
Vcl=+/-78mv
Power Limiter accuracy
Vcl=+/-15mv
Power Limiter
Power Limiter
Inductor
Inductor Input AC Voltage
Input AC Voltage
2. Improvement of Load Regulation by Utilizing gm AMP in Feedback Loop In case voltage amplifier is feedback type, the current via feedback resister influences load regulation. By using gm amplifier, there is no current path in the circuit. So that, load regulation can be improved.
Competitor’s
R2A20115
VOUT
3. Hold Function at Brownout
Additionally, contributed by the improvement in accuracy of circuit (2% to 1.6%), the resister to adjust the reference voltage becomes unnecessary.
Error AMP
R2
VEO
R1
R1
1.6%
VREF
FB
Error AMP
Detection level
PFC Output voltage
VOUT
Brownout Detection level
Hold Counter
VEO
VOUT
Hold time can be adjusted.
FET OUT (R2A20115)
2% R2
Brownout AC Input
Final Final adjustment adjustment of of resister resister is is not not needed. needed.
VEO
VREF Io
5 4 3 2 1
By hold function, the IC keeps working if the duration of brownout is shorter than the preset hold time. So that it can recover rapidly.
The IC restarts safely with soft-start mode if the duration of brownout is longer than the preset hold time.
4. Prevention of “Coil Vibration” and Overshooting Contributed by Dynamic OVP The IC newly integrates Dynamic OVP circuit, which limits peak current by making the width of OUT pulse narrower gradually and then prevents over voltage, when over voltage is detected, in addition to Static OVP circuit, which stops the output pulse. Even if overshooting occurs in transition period, such as the period of start-up or sudden variation of load, Dynamic OVP keeps the output pulse on, so that, “coil vibration” can be prevented.
Operations just after sudden variation of load <0.1A-1.3A>
Error Amp Block
Dynamic OVP
Renesas Electronics URL http://www.renesas.com/pfcic
With Dynamic OVP ©2010. Renesas Electronics Corporation, All rights reserved.
Without Dynamic OVP
