Chip to turn on/off various circuits

martin

Sorry - forgot to mention that it has to supply up to 100mA @ 5V

Ross

Then a 74HC138 + PChan FETS

James

Two possibilities here: - either the "7HC138" (with no 4, so not 74HC) is some kind of power controller I don't know about (Google did throw up a few links, but from their context, they *look* like typos) - or you're talking about the 74HC138, which is a one-of-eight decoder (with enables). Which makes no sense. It's not a latch, and is not a power driver.

So: huh?

Steve

Re-reading that carefully (as one sometimes does *after* one presses the "send" key):

Ah. If the OP really means "exclusive" in the sense of "only one at a time" (I'd taken "I want to be able to control which circuits are on" rather more literally), then I see your point. However, he'd still need 3 control lines (2 address, 1 enable), as opposed to 4.

Steve

If you can switch the low side, TI has some nice DMOS open-drain power shift registers that allow you to switch 8 lines per chip using a few port pins. Essentially an HC595 with a N-channel MOSFET on each Q output.

Best regards, Spehro Pefhany

Thanks for all the replies.

Sorry, I should have said "control which circuit is on".

I have solved the problem anyway - I've put an extra latch on my portb bus and am using that to control the shutdown pins on a few LP2985 LDO regulators.

Thanks all, Ross

Ross Marchant scrobe on the papyrus:

Look at the Allegro UDN2987 or for an addressable latched version the A6259.