powering IR receiver from uC output pin

[djacobow]

I've got a battery powered device under development that has IR remote control receiver. The receiver datasheet (https://www.vishay.com/docs/82471/tsop772.pdf) suggests that the supply current is 0.8 mA and the the max supply current is 5mA (presumably, when the output pin is driving 5mA)

Right now I am powering it through a largish PFET that controls a bigger power rail shared by some high current consumers. I want to do the IR receiver separately. I could use another PFET, but not using anything is preferable.

Can anyone think of a reason that I cannot power down this receiver by driving its Vcc directly from a microcontroller pin? The output current will never be anywhere near 5mA because the output is going right back to an input pin of the same microcontroller.

[MosherIV]

Can anyone think of a reason that I cannot power down this receiver by driving its Vcc directly from a microcontroller pin?

Microcontrollers usually have a limited amount of current that ALL the gpio pins can soure, notjust on each individual pin. You need to check the total current that ALL the gpios are going to output.

Hint: the amount of current microcintrollers can sink is higher than they can source.
To control the ir receiver by sinking current, put the gpio in open collector mode. In effect, the micro is switching the 0V on/off instead of the power.

This may not be an problem, do the check like a good engineer 

[perieanuo]

Just add one transistor and one resistor, your BOM won't explode


Envoyé de mon iPad en utilisant Tapatalk

[bson]

It will probably be fine, but do wire it up on a breadboard to check.  5mA is probably the maximum output current into a shorted load, but a GPIO input pin will be very high impedance and draw very little current.  So supply current will be dominated entirely by what the device itself needs, which is probably very little (the < 1mA figure).  But you can't know for sure until you check for yourself.