General
Description
The CM6903/4 is a space-saving
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 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 CM6903/4 includes circuits for the implementation of a leading
edge, average current "boost" type PFC and a trailing edge, PWM.
The CM6903's PFC and
PWM operate at the same frequency, 67kHz. The PFC frequency of
the CM6904 is automatically set at half that of the 134kHz PWM.
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
- 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, Trifault
Detect, PFC VCCOVP, Precision -1V PFC ILIMIT
- 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 protection
- 10mS Digital PWM
softstart
- Precision PWM 1.5V
current limit for current mode operation
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Applications
- Desktop PC Power
Supply
- 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
- CM6903IZ:
9-PIN SIP (Z09), 16-PIN SOP (S16)
- CM6904IZ:
9-PIN SIP (Z09)
