LTM4686 and -1 SVIN and INTVCC

mbrowning on Apr 7, 2022

I want to replace an obsolete Intersil part with the LTM4686 (single output configuration) and I would like to design the replacement to use either LTM4686 or LTM4686-1 with 12V VIN.

It seems from the datasheet I can just add a separate 5V LDO to supply INTVCC with either part, and have 0ohm's to connect SVIN to VIN for the 4686 and SVIN to INTVCC for the 4868-1. Is this correct?

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Jhun
Apr 8, 2022 +1 verified
Hi,

This is correct. Add a decoupling capacitor to the SVin pin if not connected to Vin in accordance to the datasheet. You can also simulate the design through LTSpice to make sure that the design works…

+1 Jhun

on Apr 8, 2022 12:22 AM
Hi,

This is correct. Add a decoupling capacitor to the SVin pin if not connected to Vin in accordance to the datasheet. You can also simulate the design through LTSpice to make sure that the design works as intended.

Regards,

Jhun
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0 mbrowning on Apr 8, 2022 2:24 PM in reply to Jhun

Thank you.

Is there any risk of damage if VIN and INTVCC don't come up at the same time?

It would be more efficient if INTVCC came from backplane 5V (with VIN coming from backplane 12V). But if for some reason 5V (INTVCC) or 12V (VIN) does not start up immediately I wouldn't want to damage parts on this expensive board.
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0 Jhun

on Apr 10, 2022 11:44 PM in reply to mbrowning
This should not be a problem. The internal MOSFETs will not be switching if both are not present.

Regards,

Jhun
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