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Low
Pin Count PFC/PWM Controller Combo- CM6903A
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General
Description
The CM6903A is a space-saving
PFC-PWM controller for power factor corrected, switched mode power
supplies that offers very low start-up and operating currents.
For the power supply less than 500Watt, its input current shaping
PFC performance could be very close to CM6800 or ML4800 architecture.
Power Factor Correction
(PFC) offers the use of smaller, lower cost bulk capacitors, reduces
power line loading and stress on the switching FETs, and results
in a power supply fully compliant to IEC1000-3-2 specifications.
The CM6903A includes circuits for the implementation of a leading
edge, input current shaping technique "boost" type PFC and a trailing
edge, PWM.
The CM6903A's PFC and
PWM operate at the same frequency, 67kHz. This higher frequency
allows the user to design with smaller PWM components while maintaining
the optimum operating frequency for the PFC. An PFC OVP comparator
shuts down the PFC section in the event of a sudden decrease in
load. The PFC section also includes peak current limiting for
enhanced system reliability.
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Features
- Patent Number #5,565,761,
#5,747,977, #5,742,151, #5,804,950, #5,798,635
- Pin to pin compatible
with FAN6903/4
- Enable lowest BOM
for power supply with PFC
- Internally synchronized
PFC and PWM in one IC
- Patented slew rate
enhanced voltage error amplifier with advanced input current
shaping technique
- Universal Line
Input Voltage
- CCM boost or DCM
boost with leading edge modulation PFC using Input Current Shaping
Technique
- Feedforward IAC
pin to do the automatic slope compensation
- PFCOVP, PFC VCCOVP,
Precision -1V PFC ILIMIT, Tri-Fault Detect comparator to meet
UL1950
- No bleed resistor
required
- Low supply currents;
start-up: 100uA typical, operating current: 2mA typical.
- Synchronized leading
PFC and trailing edge modulation PWM to reduce ripple current
in the storage capacitor between the PFC and PWM sections and
to reduce switching noise in the system
- VINOK Comparator
to guarantee to enable PWM when PFC reach steady state
- High efficiency
trailing-edge current mode PWM
- UVLO, REFOK, and
brownout protectionu Digital PWM softstart: CM6903A (10ms)
- Precision PWM 1.5V
current limit for current mode operation
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Applications
- Desktop PC Power
Supply
- AC Adaptor
- Internet Server
Power Supply
- IPC Power Supply
- UPS
- Battery Charger
- DC Motor Power
Supply
- Monitor Power Supply
- Telecom System
Power Supply
- Distributed Power
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Packages
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