INN3694C Output Problem

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I am using INN3694C for 12V/1A & 3.3V/2A.

1. Both the Outputs are not constant.
2. At 3.3V Output - 1.3 ~ 2.15V
3. At 12V Output – 1.3 ~ 2.07V
4. Input Voltage – 230VAC
5. At BPP Pin - 5.34V
6. At BPS Pin – 1.1V ~ 2.34V
7. At V Pin – 156 ~ 186V

Help me to solve this problem.

Nishanth M,

INNO_SWITC-3.pdf219.98 KB
Transformer_Details_-EFD20.pdf310.17 KB

Hi Nishanthm, could you please try to increase the zener voltage for D2 from 8.2 to to 10V?

Thanks for your reply...........
the problem remains the same after changing the Zener Diode D2 from 8.2V to 10V.
For your Information:-
Pin No - 1 = 0V
Pin No - 3 = 0.46 ~ 1.07V
Pin No - 4 = 1.54 ~ 2.68V
Pin No - 5 = 0V
Pin No - 6 = 1.58 ~ 3.14V
Pin No - 7 = 1.95 ~ 3.11

Secondary Side Output 1(3.3V) = 1.71 ~ 3.12V
Secondary Side Output 2(12V) = 1.61 ~ 2.98

Hi Nishanthm,

From the measurements you providing it looks like the unit continuously is trying to start, but something is preventing this to happen.

The 8.2V zener will definitely short the outputs because the difference in the winding voltages is higher. Theoretically 10V should be OK, but for the experiment make it 12V and try again.

The other reason for not starting could be that the winding directions are incorrect. On the schematics they look right but is relatively easy to do a mistake when winding the transformer.

That is the next thing to check if the unit still does not start with 12V zener.

Sorry, I just now realize that on the schematics the bias winding is not correct. Please reverse the pins on the bias winding.

Thanks for your reply.........
I interchanged the bias winding still, the same problem and I tried 12V Zener also at D2. There is no improvement.........
Help me to solve this problem..........

Hi Nishanthm
Both documents you send contradict each other.
Looking at the transformer data in Transformer_Details_-EFD20 .pdf the the secondary wingdings are in AC stack - both secondaries shared the short-circuited pins 8, 9.
Then, looking at the schematics in the document INNO_SWITC-3 .pdf both pins 8 and 9 are separated and both secondaries are independent.
If the transformer drawing is correct than, the transformer shorts the 12V rectifier when internally connects pin 8 to pin 9.
Separate the pins 8 from 9 in the transformer as shown in your schematics. And please correct the documentation to match.