CM6800A
L
OW
S
TART-
U
P
C
URRENT
PFC/PWM C
ONTROLLER
C
OMBO
GENERAL DESCRIPTION
The CM6800A is a controller for power factor corrected,
switched mode power suppliers. 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 ML4824, CM6800A
includes circuits for the implementation of leading edge,
average current, “boost” type power factor correction and a
trailing edge, pulse width modulator (PWM). Gate-driver
with 1A 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.
CM6800A includes an additional folded-back current limit
for PWM section to provide short circuit protection function.
FEATURES
Patent Number #5,565,761, #5,747,977, #5,742,151,
#5,804,950, #5,798,635
Pin to pin compatible with ML4800 and FAN4800
Additional folded-back current limit for PWM section.
23V Bi-CMOS process
VIN OK turn on PWM at 2.25V instead of 1.5V(ML4800).
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 (100
μ
A 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, Low Power Detect Comparator
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
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
PIN CONFIGURATION
SOP-16 (S16) / PDIP-16 (P16)
Top View
1
2
3
4
5
6
7
8
IEAO
I
AC
I
SENSE
V
RMS
SS
V
DC
RAM P1
RAM P2
VEAO
V
FB
V
REF
V
CC
PFC OUT
PW M OUT
GND
DC I
LIMIT
16
15
14
13
12
11
10
9
2009/08/10
Rev. 1.6
Champion Microelectronic Corporation
Page 1
CHAMP [ CHAMPION MICROELECTRONIC CORP. ]
