WEBENCH® Tools/LM5175EVM-HP: Inductor thermal different with webench thermal different

user3480711

Prodigy 50 points

Part Number: LM5175EVM-HP
Other Parts Discussed in Thread: LM5175EVM, LM5176

Tool/software: WEBENCH® Design Tools

I checked the LM5175EVM Inductor temperature when Vin24V and Vin36V both no load.

why the L1(chock) temperature is too high different with webench thermal simulation at no load.

over 7 years ago

0 Youhao Xi over 7 years ago

TI__Guru* 78645 points

We need to investigate this on bench. Could you tell what is your actual inductor temperature?

0 user3480711 over 7 years ago in reply to Youhao Xi

Prodigy 50 points

Inductior temp is 50 deg and 70deg In EVM when vin 24v and vin 36v

0 user3480711 over 7 years ago in reply to Youhao Xi

Prodigy 50 points

Sorry, Have any update?

0 Youhao Xi over 7 years ago in reply to user3480711

TI__Guru* 78645 points

I checked the EVM and inductor does get heated up at no load. It is because there is circulating current in CCM mode. At 24V, the inductor has a peak ripple current of about 5A, resulting in both the core and conduction losses. At no load the major power dissipation is caused by the core losses. Since the ripple current will not change much in CCM, so the core lossess would not change much vs load.

To limit the power dissipation at no load, you may consider to set the EVM to DCM mode.

0 user3480711 over 7 years ago in reply to Youhao Xi

Prodigy 50 points

Thank your support , ok I got your answer . But I have another issue, if I used LM5176 how to solve the ccm mode issue ? Because my condition is vin 9~36v and vo 12v that inductor value always used boost mode condition to design , so when vin is 36V that inductor temp always too high at no load, so how can I do ?

0 Youhao Xi over 7 years ago in reply to user3480711

TI__Guru* 78645 points

LM5176 has lower current limit, and tighter current limit deviation. You should select a larger inductance to limit the inductor ripple current, and hence the core losses.

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WEBENCH® Tools/LM5175EVM-HP: Inductor thermal different with webench thermal different