LM3478Q-Q1: Automobile grade circuit devices heat up to 100 degrees Celsius, help find out why

zhang ping

Part Number: LM3478Q-Q1
Other Parts Discussed in Thread: LM3478

MOSFET is PD70N1053,Vin 6~16V，Vout 12V or 15V ，Iout=1A。All the devices on the circuit have a serious fever, up to 150 degrees Celsius, and the devices with heat sinks up to 100 degrees Celsius. The following table is the test results, please help to analyze the reasons? What should PCB pay attention to?

over 5 years ago

0 Garrett Roecker over 5 years ago

TI__Mastermind 21720 points

Hi Zhang,

Thanks for reaching out with your questions.

Can you please let me know what components are getting hot? Is it just the MOSFET or is the LM3478 getting hot as well? One quick suggestion is to lower the gate resistor (R455) value to 0 ohm to see if there is an improvement.

Thanks,

Garrett

0 zhang ping over 5 years ago in reply to Garrett Roecker

Genius 3505 points

The MOSFET and LM3478 are all hot, and about 100℃ . I put heat sinks on them all. If there isn't heat sink ,they are 150 ℃. I will try your advise .and And please help me to see why. ?

0 Garrett Roecker over 5 years ago in reply to zhang ping

TI__Mastermind 21720 points

Another suggestion is to remove R458. This is probably increasing the drive current of the LM3478 that might be increasing the temperature.
-Garrett

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LM3478Q-Q1: Automobile grade circuit devices heat up to 100 degrees Celsius, help find out why