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Substitute LM2676 simple switcher

Hi

LM2676S-ADJ lead-free are hard to get now. Has anyone tried substituting LM2670 series with success? I am looking at the datasheets trying to find a trap. Not using sync. Need a direct substitute without any changes to surrounding passive parts if possible.

Geoff

Reply to
g c
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Fixed voltage version seems to be in better supply. What voltage is your design?

Reply to
Ed Lee

You can use the 12V version and use around 7K external R2. No R1 and no change to your circuit board.

Reply to
Ed Lee

I'll look at that option, thanks.

Reply to
g c

Watch out for thermal drift and initial accuracy, though--if the on-chip resistors are diffusions or polysilicon rather than metal, they're typically +-30% initially and have tempcos between 500 and about 5000 ppm/K. (See e.g.

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.) You'd probably be better off keeping the voltage divider but reducing its impedance level by 10x or so (and changing the ratio, of course). That way you're basically taking ratios of resistors of the same type.

Before there were LM317s, people used to do that with LM309s and 7805s.

Cheers

Phil Hobbs

Reply to
Phil Hobbs

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