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How can I find the maximum sinking and sourcing currents of different pins in a microcontroller (namely 8051) from its datasheet?
Edit: I have downloaded and looked at the datasheet, I just can't read this information from it.

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  • \$\begingroup\$ The one I'm looking for is AT89C51 which is a configuration of Atmel 8051 \$\endgroup\$ May 18 at 16:56
  • \$\begingroup\$ How much do you need? \$\endgroup\$ May 18 at 18:28
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The values given for V(oh) and V(ol) state the current that the device can provide and still provide reliable logic levels. For a CMOS device you can estimate the max Rds(on) for the driver FET pair and thus establish what the theoretical maximum current would be for the pin.

There’s also a max total current specified for all the pins in aggregate, and per port. See Note 6 in the DC Characteristics, in the datasheet here.

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Assuming this is the uC you are referring to:

enter image description here

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The test method for output current is to measure the max or min voltage for a std. current level used within a logic family.

When using it for other purposes, consider the RdsOn of the CMOS discrete model.

enter image description here

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