InnoSwitch3-EP Family INN3694C

Hi Sulim,

Thank you for using Power Integrations products.
Capacitance is generally affected when operating temperature changes.
Auto-restart behavior at -40C could be because of BPP capacitance value change.
Please check the BPP capacitor and make sure and it is X7R or X5R type, 0805 package or larger, and placed close to the InnoSwitch3 IC in the PCB layout.

Regards,
PI-Spark

Good afternoon, the capacitance of the capacitor at a temperature of -40 ° decreases from 4.7 mkF to 2.1mkF, I put 2 parallel-connected capacitors of 4.7mkF each, but this did not help, the capacitor C70 was also increased, the circuit is attached to the file, the capacitance should be 2.2 mkF i increased to 4.7mkF, but at a temperature of -40 ° everything repeated the power supply unit tries to start and unsuccessfully makes an attempt to blink the LED at the output as a load, the LED and ballast resistor have a maximum current of 10-15 mA. Maybe I did not calculate the transformer correctly, I am enclosing a calculation file for you, please help me understand what freezes?

Hi Sulim,

The calculation file you provided looks good.
What value of output capacitance are you using?
Can you also check the output voltage waveform during startup?
Since capacitance decreases with temperature, it could be possible that the effective output capacitance at -40C becomes too low and it will cause output voltage overshoot.
If the Feedback pin of InnoSwtich3 becomes 20% higher than the expected value, output overvoltage protection will be triggered and cause an auto-restart.
You may refer to the InnoSwitch3-EP datasheet or the attached image.

Regards,
PI-Spark

Good afternoon,
We would like to replace the SR MosFET (AO4476A) on our Offline Power supply (Output=5V/3A) built around an Inno3674C by a simple Diode.
Please could you help us by providing an example schematic to do that and what kind of diode is best suitable to replace the MosFET ?
Thank You
Best Regards

Good afternoon,
We would like to replace the SR MosFET (AO4476A) on our Offline Power supply (Output=5V/3A) built around an Inno3674C by a simple Diode.
Please could you help us by providing an example schematic to do that and what kind of diode is best suitable to replace the MosFET ?
Thank You
Best Regards

Hello JACKYB,

Thank you for reaching out to us through this forum page. We are more than willing to help you in your inquiry but if may I suggest, please kindly create another ticket for this one or create new post. If you think that this thread is relevant to your inquiry, you may simply copy the link in your new post.

We hope to hear from you again.

Thanks and Best Regards,

PI-Lupin the Third

Good afternoon, thank you for your help, your recommendation to increase the capacitance helped us by increasing the capacitance of the output filter capacitor from 470mkF to 1000 mkF and the capacitor from 330mkf to 1000mkF, problems with starting went away. The source began to start up confidently even at -42 ° C, your recommendations helped a lot, Thank you very much for your help !!! We will use your chips in other devices! Sincerely, Electronic Engineer Sulim Vladimir.

Hi Sulim,
Good to hear that the design has been fixed.
You may always contact us if ever you need support in using Power Integrations products, we will be happy to help you.
Regards,
PI-Spark