LM22676: Cause of short circuit in LM22676

user5280246

Part Number: LM22676

In the above circuit, Short circuit occurred in VIN pin and SW pin at the beginning of test, which has not happened before.What was the cause?Is there a problem with the LM22676 or with the testing process?

over 7 years ago

0 Katelyn Wiggenhorn over 7 years ago

TI__Genius 11040 points

Hello,

Would you be able to help clarify your test and short circuit conditions?

What test are your running when you see this behavior? Can you explain the test set up and what you are measuring?

Second, when you say short circuit, are you referring to the device operating in current limit, or are you referring to VIN being shorted to SW pin (VIN=SW)?

Thank you,
Katelyn Wiggenhorn

0 user5280246 over 7 years ago in reply to Katelyn Wiggenhorn

Prodigy 100 points

Hello,

First of all, thank you for your reply.

This problem was found when writing the program. It was found that the program could not be written, the output was abnormal after measurement(Input =output =12V).VIN pin and SW pin of the chip were short-circuited after power power off(VIN=SW).

Thank you,
Baron Li

0 Katelyn Wiggenhorn over 7 years ago in reply to user5280246

TI__Genius 11040 points

Hello Baron,

If I understand correctly, the device has a short (VIN=SW) after the first start up at 12V. Is this correct? Did the device operate normally before this start up or was it on initial start up? Can you replicate this failure on additional boards?

In regards to your test set up:
1. Are you powering with a DC power supply turning on (not a hot plug start up)? Is this the time you turn the board on?
2. Is the device loaded? If so, is it a resistive load or electronic load?
3. Do you have additional connections to the board?

Thank you,
Katelyn Wiggenhorn

0 user5280246 over 7 years ago in reply to Katelyn Wiggenhorn

Prodigy 100 points

Hello Katelyn,

Thank you for your help.We have found that an abnormal capacitance around LM22676 caused the failure.May I ask if you have any Suggestions or notes about LM22676?

Thank you,
Baron Li

0 Katelyn Wiggenhorn over 7 years ago in reply to user5280246

TI__Genius 11040 points

Hi Baron,

I am happy to hear that you have found the root cause of your failure.

In the product folder, you will find the datasheet, EVM, and quickstart calculator. I would recommend starting any design with the LM22676 with the Quickstart calculator which will help you chose components for your design. Second, the datasheet's application section is a great resource for understanding the recommended components within the applications circuit. Lastly, the EVM provides a great example of the applications circuit as well as optimized layout.

Best Regards,
Katelyn Wiggenhorn

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LM22676: Cause of short circuit in LM22676