UCC28810: Connection doubts

Dear Hong Huang,

                      Thank you for the reply, sorry, there is a correction its US1k-13 ( D6 ) instead of that I am using 1n4007.  And also I would like to know where should I connect the load? Is it across VDC &  TP3  OR   VDC and VAUX.       ??

Thanks In advance

Regards

Novin George Thomas

Dear Hong Huang,

                              Thanks for the reply, even though problem are there, the output voltage is 63VDC, so i connected a 60VDC 300mA LED string across the output, it glowed brightly and faded to dim the voltage got reduced to 53Vdc, when i remove the load it will rise to 63Vdc. kindly find the other observation and changes i made

1.  Voltage across IC pin 8 (VDD) and pin 6 (GND) is fluctuating from 15.6V to 10.2V rapidly

2. Voltage across IC pin 3(VINS) and GND is 1V

3. Voltage across IC pin 1(VSENSE) and GND is 1.6V,

Note : Subject to availability I used  820K  for R14 and R15 and 47K 1W for R2 and R5.

The output voltage is increasing from 0 - 63Vdc very slowly only.

The transformer is made locally as per the specification below.

Kindly look into these issues please,  and transformer details are blow

The transformer winding and inductance details  G095026LF r 6.pdf

Are you testing PMP4862? If not, please provide your full schematics for review.

Dear Sir,

           Yes I am testing PMP4862 , for a better clarity I am attaching the circuit schematic  which i made the prototype, below. I do believe that is the circuit for PMP4862.1 (Output Voltage 1)

ie: Vin (Min) : (V)85,  Vin (Max): (V)265,  Vout (Nom):  (V)100, Iout (Max):  (A)1.2, Output Power: (W)120,  Isolated/Non-Isolated: Isolated, Input Type : AC , Topology: Flyback- PFC

Kind find the pdf below

3817.Page 1.pdf

The page 1 circuit output between TP1 and TP3 should be 110V so if you connect a 60V LED string, the string is likely to be burn out.

The first thing is to make no load output voltage (TP1 to TP3) is at about 110V before you connect LED string. If you want to connect a 60V LED string, then the output voltage needs to adjust to 60V.

But since you are testing PMP4862, it is better to keep the same output 110V.

Please disconnect LED Driver A, B and C from the circuit of Page 1 (PFC/Flyback converter). So only test page 1 circuit. At no load, page 1 circuit output voltage between TP1 and TP3 should be about 110Vdc, with ac input 115Vac or 220Vac. Please let me know your test result.

Dear sir,

       Thank you for the reply,  I made the prototype of the Page 1 circuit only., I will update the test result tomorrow, need some more time to recheck,

Kind Regards

Novin George Thomas

Dear Sir,

         Still the output voltage is around 73.5V

and the irony is Vgs = 0V, Vds: 300V I don't know how the output is getting to  73V that also slowing increasing from 0 to 73V. it will take around 4 mins to reach that level

Voltages on IC PINS

Pin 1: Vsense : 1.52 -1.68 V (Fluctuating)

Pin 2: EAout : 0- 4.9V ( Fluctuating )

Pin 3: Vinsense: 1- 1.3 ( Fluctuating )

Pin 4:  Visense: 0V  Pin5: TZE : 0.5V ( Fluctuating )

Pin 6: GND

Pin 7: GDRV : 0V

Pin 8: VDD : 11.10 - 15.20Vdc ( Fluctuating )

• The previous LED load didn't get damaged !

My Queries

1. What may be reason for fluctuating Vdd? Vsense, Vdd & Vinsense is stable when IC is removed
2. What all are the factors of Output Current ?

Dear Sir,

            Thanks for the reply. Here are the values of the requested resistors, below and tomorrow I will try to capture and send the waveform of Gdrv ( IC Pin 7 )

• R23 : 22K 1/4W
• R28 : 1M   1/4W
• R9   : 56E 1/4W

And also I have another doubt Sir, today I found another reference design ( PMP 4530 ) of LED driver with UCC28810 which has output of 80V 2A ( http://www.ti.com/lit/df/slur337/slur337.pdf

Dear Sir,

             At the Gdrv ( pin 7 ) , Vgs  I couldn't find any waveform in DSO. I also suspect one thing, what happens if I used MMBT3906 instead of MMBT2709 ( Q3 )?