На букву Х и если есть что-то после нее можно не обращать внимания. Она указывает на отсутствие галогенов и свинца в составе м/с.
CM6800 - первая (самая старая) ревизия,
CM6800A - вторая
CM6800G - третья
Между ними существенных отличий нет, по идее все они взаимозаменяемы. Дальше чуть сложнее.
CM6800T - турбо ревизия, которая работает на повышенной частоте.
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
CM6800U мало чем отличается от CM6800Т и взаимозаменяемы, а вот CM6800UВ в корне отличается, т.к. PWM и PFC секции работают у нее на разных частотах, отличающихся в 2 раза.
CM6800U/CM6802U/CM6862U 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 CM6800U/CM6802U/CM6862U 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 (Feed-Forward Function)
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 CM6800U/CM6802U/CM6862U is pin to pin compatible with CM6800 family.

To start evaluating CM6800U/02U/62U from the exiting CM6800, CM6800A, or ML4800 board, 6 things need to be taken care before doing the fine tune:
1.) Change R AC resistor (on pin 2, I AC ) from the old value to a higher resistor value between 4.7 Mega ohm to 8 Mega ohm. Start with 6 Mega ohm for R AC first.
2.) Change R T C T pin (pin 7) from the existing value to R T =5.88K ohm and C T =1000pF to have f PFC =68KHz, f PWM =68KHz, fR T C T =272KHz for CM6800/02/62UA ; f PFC =68KHz, f PWM =136KHz, fR T C T =272KHz for CM6800/02/62UB
3.) Adjust all high voltage resistor around 5 mega ohm or higher.
4.) VRMS pin(pin 4) needs to be 1.14V at VIN=80V AC for universal input application from line input from 80V AC to 270V AC .
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.) PWM’s Ramp2 internal have feed-forward current from VFB Pin. This pin contact to VCC or Vref Pin resistor need reduce value from the exiting CM6800A/02.

Т.е. если будешь ставить T или U вместо ранних А/В/G то придется менять обвес.

С полгода назад озадачивался проблемой взаимозаменяемости и задал вопрос производителям, ответ получил очень расплывчатый, после чего пришлось искать даташиты и исследовать их.

Hi Alexander,
Cm6800 is same family series.
For Suffix U means design working voltage frequency.
Follows by A or B means die revisions
Follow by G means ROHS parts.
You can replace them using Cm6800 series. Just work with some bias RLC circuits for fine tuning.
ML4824 not advisable to use it. This is from different Mfgr.

Tks & Rgds
E-Direct - Kelvin