LMR33620: Alternative with an adjustable soft start time

Patrick Ruf

Part Number: LMR33620
Other Parts Discussed in Thread: LMR14020-Q1

Tool/software:

Hi,

We use the LMR33620ADDA in several projects. For a new project I'm looking for a similar part but with an adjustable soft start time that can be configured down to 1ms.
If possible it should have a higher maximum input voltage (as e.g. LMR36520FADDA) as 36V is always a bit limiting for 24V input voltage.

Output voltage is 3.3V. Synchronous step down is mandatory.

A fully integrated power module (integrated inductor) is also possible.

Any suggestions are highly appreciated.

Thanks and best regards,

Patrick

3 months ago

0 Andrew Kutzler 3 months ago

TI__Mastermind 23795 points

Hi Patrick,

Is 30V acceptable? This part SS can be configured to 1mS minimum.

https://www.ti.com/product/TPS62932

Thanks,

Andrew

0 Patrick Ruf 3 months ago in reply to Andrew Kutzler

Genius 4965 points

Hi Andrew,

No, unfortunately, 30V is not acceptable. A nominal 24V supply can go up to 30V. With surge protection we need at least 36V.

Regards,
Patrick

0 Andrew Kutzler 3 months ago in reply to Patrick Ruf

TI__Mastermind 23795 points

HI Patrick

LMR14020-Q1 is a 40V converted with softstart. You can configure it to 1mS by connecting a 4nF capacitor to SS.

https://www.ti.com/product/LMR14020-Q1

Thanks,

Andrew

0 Patrick Ruf 3 months ago in reply to Andrew Kutzler

Genius 4965 points

Hi Andrew,

It's 40V but not synchronous...

Regards,
Patrick

+1 Andrew Kutzler 3 months ago in reply to Patrick Ruf

TI__Mastermind 23795 points

Hi Patrick,

Unfortunately most of the newer >36V synchronous parts we have a fixed soft start value. It seems like the only parts that have adjustable soft start are either lower voltage or non-synchronous.

Sorry if this is answer doesn't satisfy you.

Thanks,

Andrew

0 Patrick Ruf 3 months ago in reply to Andrew Kutzler

Genius 4965 points

Hi Andrew,

So you came to the same result as me. I was hoping that there will be a hidden part somewhere.
The problem is that most of the new C2000 microcontrolers need a supply ramp rate of at least 3mV/us. This results in a ramp time of 1.1ms or faster for a 3.3V supply. But most newer DC/DC parts from TI (VIn>=36V) have a fixed soft start time of around 4ms.

Regards,
Patrick

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LMR33620: Alternative with an adjustable soft start time