Failure of INN3168C-H101 and Rfwd resistor
Hello Everyone,
I am making a 85-265V AC universal power supply with 30V 1.8A output using INN3168C-H101.
I encountered a problem during the tests, sometimes when I power the device, the 47R fwd resistor burns and the INN3168C gets damaged. However, if the device manages to start properly, it can work for hours. What could be the reason for this?
I have burned about a dozen INN3168Cs.
Comments
Hi Yavus,
We're sorry to learn that you've had issues with your current design. After reviewing the schematics you provided, we see that you require a 30V and 1.8A output.
The maximum allowable output voltage of the VOUT pin of the InnoSwitch3-CE is only up to 27V, as indicated in the device datasheet on page 19. It seems there’s a bug in our PI Expert tool that mistakenly allows the generation of a design with a 30V output, and we sincerely apologize for this oversight. It appears that the 30V output led to the failure on the secondary side, which in turn resulted in the explosion on the primary side. I want to assure you that we’re taking this issue very seriously and have escalated it to the appropriate department right away.
We’ll continue to review your current design and will get back to you with an update soon. Thank you for your understanding.
Hi PI-Hueka,
Thank you very much for the information. We are waiting for your return as soon as possible for a solution. This project is very important to us.
Hi Yavus,
Thank you for your response.
For applications with output voltage greater than 27V, we suggest implementing the configuration from LYTSwitch, which implements a Schottky diode as the secondary rectifier instead of an SR FET and using a secondary bias winding. You may refer to the following reference designs:
In this implementation, the SR pin will be disabled by grounding the pin to the Ground pin, and the VOUT pin will be tapped on the positive rail of the secondary bias winding instead of the main output.
It sounds like you might be experiencing inrush current issues, which can stress the 47R resistor and the INN3168C during startup. Check if adding an NTC thermistor in series with the input can help limit the inrush current. Also, make sure your snubber network around the INN3168C is properly tuned to protect against voltage spikes. Lastly, verify that your transformer or inductor design meets the required specs to avoid saturation under load. Hope this helps!