problem -start moment with this design idea -pmp 4715

I have sent this information to the designer of the PMP4715 reference design.  He should be contacting you shortly.  Can you provide more information on your design and the difference between the operating waveforms in the two modes?

hi TI,

I have tree mains difference from original idea.L1 -33mH ,Q1 -IRF840,D5-double in parallel HER602

other components are totally same.The problem is when I turn on  driver (pcb on pmp 4715 and load 20ohm/80watt)-my power analyser show me parameters:0,97pf ; 44.1watt;  48va,and work 3-4 hours without problem,  but when I switch the driver the results are 076pf;40.2watt  ;52.2 va and work 2-3 hours without change,,!!!!!

This is abmormal..according to me.

after  several times switches..tne board  work like firs variant with 0.97pf...this is the my problem

Hello,

Can you post a screenshot of the input current?

Is the PMP4715 connected by an isolation transformer and/or a Variac?

If yes, which is the nominal power of the isolation transformer?

Best Regards

Hello again,

Sorry, I didn't see your last post....

Now it looks a little clearer to me. I think the problem comes from the load, since it is resistive and the equivalent voltage very close to the limit (28V).

The power supply is designed to work with an LED string, which behaves like a zener diode: it clamps the voltage, therefore this impacts also the power factor.

Also, if you reach the 28V limit, the absorbed current will be very distorted because of the overvoltage protection, made by D13.

Please try to put a load resistor below 20 Ohm, or better an LED string.

Thanks.

Hi and thanks about your recommendation.....but  thoroughly what  my question why sometimes work it good(0.98 pf     88%eff),other times bad(0.77 pf   78% eff).

I don't make any change .....when I switch the my boards???

Hello,

Actually this is weird, but it might depend on the overvoltage protection that triggers only when the converter warms up. The threshold depends on a zener diode, so it's not so precise. Please try to reduce the resistor value of the ouput load or connect an LED string, and let me know.

Thanks.

ok

thanks again..I'm going to test with 7 resistors in series with parameters each of them:2.2 ohm  and 10 W 

let's hope that ,everything will be all right.

best regards

Hello,TI

problem with change parameter get in own answer,but,again begin other problem -I out  =1.8A(differently-for other evm-1.5A;1.6A;1.8A;1.84A;1.85A/ I have 5 emv/.....

I think, looking for......mix component ,,but not a trace of it..

bye bye

see you

best regards

Hello,

Please let me know if you find any problems or mistakes during component assembly.

Thanks

Hi TI

I post the table with my test results,later.I plan to change R15=75k with value=80k,90k,100k,when the output current is in range:1.32 /1.40A in case of load 18.6 Ohm.

bye bye

I don't found any mistakes in assembly,::)

regards

HI TI

every things OK

I hope this pmp to change with dimmable  adapted.Can I hope your support,,,May be I will begin UCC28810,,but nex step

bye bye

best

sorry,

I wanted to tell you that i will have to use UCC28811  ,for triac dimmable pmp