How many GPIO pins could be used at the same time with STM32F207zx?

[genisuvi]

I am working in a new card ETH MAC comunications based design, with a number of digital inputs, a number of digital outputs and a number of ADC channels getting analog inputs from external sensors.

The specifications of the hardware design starts with an ETH interface and it is yet defined.

But the number of inputs, outputs and ADC is not yet defiined because it is considered to be MCU capability dependent. At this point of planing I have the task of consider which could be the maximum digital inputs/outputs and so ADC inputs working in the worst case: at the same time.

I guess it depends on current consumption. I have found this table about current values.

Output current IIO is refered to the gpio configured as output pins?

Injected current INJ is refered to the inputs? I think it is not, because injection could be possible in both cases, but.. I don't understand difference between injected current on pin and sunk current on pin. I'm asking only to be sure what this table mean.

Are those current values also applied to ADC inputs?

How can I find the real maximum number of pins at the same time? 25mA seems to be poor for 3 groups of pins. As design needs to keep a minimum number of 8 available ADC inputs. I think the card application could keep ADC group working not at the same time than the other ones. This will save total consumption.

Maybe I missunderstood the most of things. In that case please make me know.

Thanks in advance.

[waclawek.jan]

Injected current is current which flows through protection structures ("diodes"), regardless of how the pin is set. You should avoid any current injection.

If a pin is set to ADC, it is no longer five-volt tolerant anymore, its upper bound is given by VREF+..

JW

[genisuvi]

thanks,

so which is the current value that mcu is able to tolerate before getting damaged when no injected current is present thanks to correct design? 25mA?

Regarding ADC pins, the question was also about current.

regards.

[Andrew Neil]

@genisuvi​ "Output current IIO is refered to the gpio configured as output pins?"

of course: as the table said, it is the current sunk/sourced by the pin - only an output pin is going to sink or source!

"How can I find the real maximum number of pins at the same time?"

In general, that isn't limited by current - it's just the number of available output pins.

If the outputs are only being used as logic control signals, there is no significant current involved.

EDIT

The current limits are only going to be a concern if you're working with (lots of) high-current loads; eg, (high-power) LEDs.

[Andrew Neil]

"I don't understand difference between injected current on pin and sunk current on pin"

See the definition in the datasheet: