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Can I source maximum source current from weak-pull-up?

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saurav_sdpl

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weak-pull-up

I have a doub regarding weak pull-up, if my micro datasheet specifies maximum source current of 20mA @ VDD=5.5V. if i want to source 20mA from that port pin do i need to add an external strong pull or still my pin would be able to source that much current.
 

Re: weak-pull-up

weak pull ups are used only when a specific port is defined as an input, so you won't be (or shouldn't be) SOURCING any current from that pin.


Unless we misunderstood each other.
 

weak-pull-up

if you want 20 mA you need to set it to 'output' and assert a high on that pin.... the internal pull-up (weak pull-up) is only for 'input' mode on that pin...

note also that if a pin can source 20mA all the pins can't source more than 100mA or all the ports more than 200mA (of course it depends on your microcontroller (PIC? AVR?), but check the datasheet, there you will find a similar advise...)
 

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