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Andrew Lohmann
Andrew Lohmann
Senior
March 3, 2021
Solved

SMP controller such as L6726 or other as a boost regulator.

  • March 3, 2021
  • 4 replies
  • 1798 views

I would like to use a SMP controller such as L6726 or other as a boost regulator. That is use the high side output (pin PHASE) connected to 0V and my boost transistor. I would use the low side driver to drive a MOSFET as a synchronous rectifier Is this possible alternatively are there any spice models I can used to try this option?

Apologies if I have already posted this but i could not find the post?

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Best answer by FLIBR.1

Hello Andrew

you can use the L6726 to impement an Asynchronous boost converter. Use the UGATE pin to drive the main switch of the boost. PHASE pin has to be connected to the source of the switch (i.e. to GND). The booststrap cap has to be connected between BOOT and PHASE as in the standard buck. LGATE is not used, connect to GND though a 100kOhm resistor.

Hope this answers your question.

4 replies

FLIBR.1
FLIBR.1Best answer
Visitor II
March 8, 2021

Hello Andrew

you can use the L6726 to impement an Asynchronous boost converter. Use the UGATE pin to drive the main switch of the boost. PHASE pin has to be connected to the source of the switch (i.e. to GND). The booststrap cap has to be connected between BOOT and PHASE as in the standard buck. LGATE is not used, connect to GND though a 100kOhm resistor.

Hope this answers your question.

Andrew Lohmann
Andrew LohmannAuthor
Senior
March 8, 2021

I guess if I do use LGATE to drive a low side synchronous rectifier then the adaptive anti-cross-conduction function will not operate so what would the default condition be no dead-time, small dead-time, or a big dead-time?

FLIBR.1
FLIBR.1
Visitor II
March 9, 2021

HI Andrew

It's not clear to me how you would like to use the LGATE. The freewheel diode (or FET) is in high side in a Boost topology, so it cannot be driven by LGATE. This is the reason why we suggest to implement asynchronous Boost with L6726.

In any case, we never tested the anticross circuitry in conditions different than the standard buck, so we don't have an answer to your question.

Andrew Lohmann
Andrew LohmannAuthor
Senior
March 9, 2021

Thanks for both answers. I can either place an output synchronous rectify and an output schottky rectifier on my board and examine the waveforms to see if it will work or experiment with a modified Evaluation board first?

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