LM25141: Minimum turn on time and Minimum switch node pulse width

Zhi Wen Khaw

Prodigy 20 points

Part Number: LM25141
Other Parts Discussed in Thread: LM25148

Hi fellow members, I'm currently working on a design for a buck converter using the LM25141.

May i ask whether the minimum turn on time and the minimum switch node pulse width, tsw are the same?

If yes, why is the minimum turn on time is 66 ns and the minimum switch node pulse width is 70 ns?

If no, what is meant by the minimum switch node pulse width,tsw?

Thanks.

over 2 years ago

0 Timothy Hegarty over 2 years ago

TI__Guru* 75612 points

Hi Zhi,

This is the minimum controllable on time, which is relevant in high step-down ratio and/or high switching frequency applications. There may be typical and maximum specs for this parameter.

Note the LM25148 is a newer version of this controller and may have a more favorable min on-time if needed.

Regards,

Tim

0 Zhi Wen Khaw over 2 years ago in reply to Timothy Hegarty

Prodigy 20 points

I only found the minimum turn on time in the datasheet but not the minimum switch node pulse width. Which section in particular that I can find for the minimum switch node pulse width?

0 Timothy Hegarty over 2 years ago in reply to Zhi Wen Khaw

TI__Guru* 75612 points

Those two parameters are effectively equivalent, aside from the rise/fall times of the switch voltage, which are load current and MOSFET dependent.

Regards,

Tim

Power management

Power management forum

LM25141: Minimum turn on time and Minimum switch node pulse width