CM6802
N
O
B
LEED
R
ESISTOR
G
REEN
M
ODE
PFC/PWM C
ONTROLLER
C
OMBO
GENERAL DESCRIPTION
The CM6802 is a green PFC/PWM. It is the new generation
of ML4802, ML4841, ML4801 and ML4824-2. Its system
clock frequency is generated by the external RT and CT,
and then its PWM frequency is 50% of the clock and its
PFC frequency is 25% of the clock. CM6802 is designed to
be pin-pin compatible with CM6800 family, ML4800 family
and ML4824 family. Its PWM (DC to DC section) can be
easily configured to Voltage Mode or Current Mode.
The
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green mode function can easily be designed so during the
no load condition, its input power can be less than 0.75Watt
without shutting off PFC. Its PFC green mode threshold and
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the PWM green mode threshold can separately set by
selecting the proper the RC filter at ISENSE pin (pin3) and
CT on RAMP 1 pin (pin 7). Power Factor Correction (PFC)
allows the use of smaller, lower cost bulk capacitors,
reduces power line loading and stress on the switching
FETs, and results in a power supply that fully compiles with
IEC-1000-3-2 specifications. Intended as a BiCMOS
version of the industry-standard CM6800, CM6802 includes
circuits for the implementation of leading edge, average
current, “boost” type power factor correction and a trailing
edge, pulse width modulator (PWM). Both PFC and PWM
Gate-driver with 0.5A capabilities minimizes the need for
external driver circuits. Low power requirements improve
efficiency and reduce component costs.
An over-voltage comparator shuts down the PFC section in
the event of a sudden decrease in load. The PFC section
also includes peak current limiting and input voltage
brownout protection. The PWM section can be operated in
current or voltage mode, at up to 250kHz, and includes an
accurate 50% duty cycle limit to prevent transformer
saturation.
When RAMP1 is 280KHz, fpfc is 70KHz and fpwm is
140KHz.
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FEATURES
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Patent Number #5,565,761, #5,747,977, #5,742,151,
#5,804,950, #5,798,635
fosc=2 x fpwm =4 x fpfc
No bleed resistor required
Before the chip wakes up, IAC can start up VCC
Pin to pin Compatible with CM6800, ML4824 and ML4800
(It needs to modify the values of the external component to
work properly).
User Program PFC automatic green mode threshold
(patented)
User Program PWM automatic green mode threshold
(patented)
Input power less than 0.75Watt without shutting off PFC at
no load condition.
Additional folded-back current limit for PWM section.
23V Bi-CMOS process
PWM pulse keeping for the green mode
VIN OK guaranteed turn on PWM at 2.5V instead of 1.5V
Internally synchronized leading edge PFC and trailing edge
PWM in one IC
Slew rate enhanced transconductance error amplifier for
ultra-fast PFC response
Low start-up current (30µA typ.)
Low operating current (3.0mA type.)
Low total harmonic distortion, high PF
Reduces ripple current in the storage capacitor between the
PFC and PWM sections
Average current, continuous or discontinuous boost leading
edge PFC
VCC OVP Comparator will turn off both PFC and PWM
Low Power Detect Comparator
Tri-Fault detect to meet UL1950
PWM configurable for current mode or voltage mode
operation
Current fed gain modulator for improved noise immunity
Brown-out control, over-voltage protection, UVLO, and soft
start, and Reference OK
24 Hours Technical Support---WebSIM
Champion provides customers an online circuit simulation tool
called WebSIM. You could simply logon our website at
www.champion-micro.com for details.
2003/06/25
Preliminary
Champion Microelectronic Corporation
Page 1
CHAMP [ CHAMPION MICROELECTRONIC CORP. ]
