LM5148: PFM Modulation

Keith Keller

Expert 7250 points

Part Number: LM5148

Tool/software:

Hello,

When the LM5148 is in PFM modulation, does it always use the min on time, or modulate that?

Thank you, Keith

6 months ago

0 David Baba 6 months ago

TI__Mastermind 40040 points

Hello Keith,

No, the on time is set by the Peak current limit in PFM mode. Where the PFM peak current limit is 20% of full scale current limit. Hope this makes sense.

David.

0 Keith Keller 6 months ago in reply to David Baba

TI__Expert 7250 points

Hello David,

Could you please help me with the math?

Vin = 36V

Vout = 3 - 21V

Iout Max = 8A

switching freq 220kHz

inductor 8.2uH

What is the maximum peak inductor current we could expect with 20% output, so 1.6A (8A x 0.2)?

Thank you, Keith

0 David Baba 6 months ago in reply to Keith Keller

TI__Mastermind 40040 points

What Rsense are you using Keith.

Thanks.

0 Keith Keller 6 months ago in reply to David Baba

TI__Expert 7250 points

Rsense is 1.5mOhm

0 David Baba 6 months ago in reply to Keith Keller

TI__Mastermind 40040 points

Taken off line. Thanks.

David.

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LM5148: PFM Modulation