CM6800T
(Turbo-Speed PFC+Green PWM)
http://www.championmicro.com.tw
EPA/85+
PFC+PWM COMBO CONTROLLER
Design for High Efficient Power Supply
2010/08/03
Rev. 1.2
Champion Microelectronic Corporation
1
GENERAL DESCRIPTION
CM6800T is a turbo-speed PFC and a Green PWM controller.
It is designed to further increase power supply efficiency while
using the relatively lower 380V Bulk Capacitor value.
Switching to CM6800T from your existing CM6800 family
boards can gain the following advanced performances:
1.) Hold Up time can be increased ~ 30% from the
existing 6800 power supply
2.) Turbo Speed PFC may reduce 420 Bulk Capacitor
size
3.) 420V bulk capacitor value may be reduced and PFC
Boost Capacitor ripple current can be reduced
4.) No Load Consumption can be reduced 290mW at
270VAC
5.) Better Power Factor and Better THD
6.) Clean Digital PFC Brown Out
7.) PWM transformer size can be smaller
8.) Superior Surge Noise Immunity
9.) To design 12V, 5V, and 3.3V output filters can be easy
10.) The stress over the entire external power device is
reduced and EMI noise maybe reduced; PFC inductor
core might be reduced
11.) Monotonic Output design is easy
12.) And more… Of course, the cost can be reduced
CM6800T is pin to pin compatible with CM6800 family.
Beside all the goodies in the CM6800, it is designed to meet
the EPA/85+ regulation. With the proper design, its efficiency
of power supply can easily approach 85%.
To start evaluating CM6800T from the exiting CM6800,
CM6800A, or ML4800 board, 6 things need to be taken care
before doing the fine tune:
1.) Change RAC resistor (on pin 2, IAC) from the old
value to a higher resistor value between 4.7 Mega
ohm to 8 Mega ohm. Start with 6 Mega ohm for RAC
first.
2.) Change RTCT pin (pin 7) from the existing value to
RT=5.88K ohm and CT=1000pF to have fpfc=68Khz,
fpwm=68Khz, frtct=272Khz for CM6800T
3.) Adjust all high voltage resistor around 5 mega ohm or
higher.
4.) VRMS pin(pin 4) needs to be 1.14V at VIN=80VAC for
universal input application from line input from 80VAC
to 270VAC.
5.) At full load, the average Veao needs to around 4.5V
and the ripple on the Veao needs to be less than
250mV when the load triggers the light load
comparator.
6.) Soft Start pin (pin 5), the soft start current has been
reduced from CM6800’s 20uA to CM6800T’s
10uA.Soft Start capacitor can be reduced to 1/2 from
your original CM6800 capacitor.
FEATURES
Patents Pending
Pin to pin compatible with CM6802 family, CM6800
family, and ML4800 family
23V Bi-CMOS process
Designed for EPA/85+ efficiency
Digitized Exactly 50% Maximum PWM Duty Cycle
All high voltage resistors can be greater than 4.7 Mega
ohm (4.7 Mega to 8 Mega ohm) to improve the no load
consumption
Rail to rail CMOS Drivers with on, 60 ohm and off, 30
ohm for both PFC and PWM with two 17V zeners
Fast Start-UP Circuit without extra bleed resistor to aid
VCC reaches 13V sooner
Low start-up current (55uA typ.)
Low operating current (2.5mA typ.)
16.5V VCC shunt regulator
Leading Edge Blanking for both PFC and PWM
fRTCT = 4*fpfc =4*fpwm for CM6800T
Dynamic Soft PFC to ease the stress of the Power
Device and Ease the EMI filter design
Clean Digital PFC Brown Out and PWM Brown Out
Adjustable Long Delay Time for Line Sagging
(Up to 2 Second)
Turbo Speed PFC may reduce 420 Bulk Capacitor size
Internally synchronized leading edge PFC and trailing
edge PWM in one IC to Reduces ripple current in the
420V storage capacitor between the PFC and PWM
sections
Better Power Factor and Better THD
Average current, continuous or discontinuous boost
leading edge PFC
PWM configurable for current mode or feed-forward
voltage mode operation
Current fed Gain Modulator for improved noise
immunity
Gain Modulator is a constant maximum power limiter
Precision Current Limit, over-voltage protection, UVLO,
soft start, and Reference OK
