Is the MCU STM32H743IIT6 can enable 35 GPIOs at the same time?

[EMJ.1]

Hi,

I have designed a STM32H743IIT6 based board for controlling 35 optocouplers(4N35). These optocouplers should work at the same time(worst case). Each optocoupler will take nearly 10mA current. But I have seen in the datasheet as "Total output current sunk by sum of all I/Os and control pins is 140mA". Attached an image for reference. So, is it possible to enable all the 35 gpios at the same time?

[Muhammed Güler]

You can't pull a total of 350ma from the MCU. you can drive each optocoupler with a transistor or mosfet. so you can do your job by drawing much less current from the MCU. It is also possible to reduce the number of elements by using ICs such as ULN2003.

[Tesla DeLorean]

>>So, is it possible to enable all the 35 gpios at the same time?

Yes, but they'd need to pull 4 mA or less each.

If you are driving them, and that needs 10 mA each, you'll need to buffer them, so the STM32 itself isn't driving them directly. In picking a buffering chip consider the overall current, and power dissipation requirements.