LM5010A: Using shutdown pin often

Marko Wuensch

Part Number: LM5010A

Hi,

LM5010A is used in a low ripple configuration, converting from 24 V to 5 V, with 0.1 µF soft-start cap and RON = 133 k resulting in about 300 kHz.
We have been thinking about using the shutdown pin often, say at a frequency of 10 Hz or more to shutdown for about 100 .. 200 µs. Output voltage shall not drop significantly. A large buffer is used for this.

What does it mean for the used parts in terms of component stress?

Thank you,

Regards,
Marko

over 3 years ago

0 Orlando Murray over 3 years ago

TI__Mastermind 22299 points

Marko,

If you pull the SD low the soft-start will be grounded and restart (section 7.3.6).

Cycling SD like this is not ideal for soft-start, you'd have to reduce your 20ms startup time to less than 100us, so you will lose the initial start up performance.

Let me know if you have further questions.

-Orlando

0 Marko Wuensch over 3 years ago in reply to Orlando Murray

Prodigy 110 points

Orlando,

Many thanks for the information.

Apart from the poorer soft-start performance, would the LM5010A actively discharge the output when SD is pulled low? I think it is not able to do that.

Regards, Marko

0 Orlando Murray over 3 years ago in reply to Marko Wuensch

TI__Mastermind 22299 points

Marko,

No, the converter cannot actively discharge the output during shutdown, the high-side MOSFET is off, and the diode should not conduct current.

Let me know if you have questions,

-Orlando

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LM5010A: Using shutdown pin often