How to brownout op amp

Hallo Henry,

you could use an OpAmp with shutdown - like TLV2375 from TI. Another possibility is to cut off power from your analog circuitry with a small FET like IRLML6302.

Regards Markus

Hi,

If its any help here, what I do with PIC's (25 ma for each output) is use them for a power feed for op-amps, eeproms, and other such. No muss, no fuss, just shut down anything drawing less than 25 ma. on their VCC. Also, float or drive low any data lines feeding them.

As an example...

Here, RB5 is used to power an LM324 and associated circuit.

If there are external inputs to the op-amp (suppose the op-amp is a CMOS type forming a 1:1 buffer on an input to an ADC, for example) you might want to make sure the input current is limited and/or tristate the output powering the op-amp rather than driving it low. Otherwise you could have a large current flowing from the input, through a protection diode, to the microcontroller output, to ground.

Best regards, Spehro Pefhany

Heh - the venerable LM324. You're as much of a dinosaur as I am ;). I

Steve

Hello Steve,

So do I. It's not embarrassing but just plain common sense. After all, where can you get a comparable quad opamp where each amp costs less than a nickel?

Then, look at stuff that's even older. I can't count how many times I designed in a 2N2907 or its SMT sibling and there is no end in sight.

Hah, we've got six trees here on the lot....

Regards, Joerg

The LM324 was the most frequent mention in the recent "Name your favorite analog IC's" thread in s.e.d.

Four amplifiers for less than a dime. What's not to like?

Best regards, Spehro Pefhany