How much minimum current needed on any GPIO pin for driving it?

VShah.4 · ‎2022-03-22

Paul1 · ‎2022-03-22

Given these are FET inputs the input current is negligible for standard GPIO pins, i.e. a 100Kohm pullup or pulldown can easily drive an STM32 GPIO input. -but- if you are hitting the pin with a high frequency digital signal, then you'll need to charge the pin's input capacitance pass the Hi/Lo voltage threshold before the new state is detected (i.e. lower resistance at higher speed data). Also if driving an analog input then you need to charge the sampling capacitor fully to the input voltage, which means a low impedance input source for higher frequency signals/sampling.

The input voltage for Hi/Lo will depend on the Vcc supplied to the IC, expect for 5V compatible pins. Check the MCU's datasheet for the specific GPIO pin's input threshold.

Paul

View solution in original post

KaushikThumar · ‎2022-03-22

Not sure about Minimum Current, but as per STM datasheet the maximum current rang is up to 25mA. you can see it in the datasheet page 58, Arm® Cortex®-M4 32b MCU+FPU, 105 DMIPS, 256KB Flash/64KB RAM, 11 TIMs, 1 ADC, 11 comm. interfaces (st.com). I search it, and assume it ranges from some uA to 25mA.

VShah.4 · ‎2022-03-22

Okay Thanks.

But it would be great if someone can help with precise value of minimum current!!

Peter BENSCH · ‎2022-03-22

Does your question refer to the fact that you want to drive a GPIO pin as an input and know the minimum current for it?

Or are you asking about the minimum current that a GPIO can drive into a connected load?

Regards

/Peter

In order to give better visibility on the answered topics, please click on Accept as Solution on the reply which solved your issue or answered your question.

Amandeep_Dhaliwal · ‎2022-03-22

I think he/she asking for threshold voltage on GPIO pin to read it as one , which is around 1.8V maybe.

Paul1 · ‎2022-03-22

Given these are FET inputs the input current is negligible for standard GPIO pins, i.e. a 100Kohm pullup or pulldown can easily drive an STM32 GPIO input. -but- if you are hitting the pin with a high frequency digital signal, then you'll need to charge the pin's input capacitance pass the Hi/Lo voltage threshold before the new state is detected (i.e. lower resistance at higher speed data). Also if driving an analog input then you need to charge the sampling capacitor fully to the input voltage, which means a low impedance input source for higher frequency signals/sampling.

The input voltage for Hi/Lo will depend on the Vcc supplied to the IC, expect for 5V compatible pins. Check the MCU's datasheet for the specific GPIO pin's input threshold.

Paul

Tesla DeLorean · ‎2022-03-22

Perhaps provide some specific context, part number and scenario, it's hard to decipher exactly what you're really in looking for and how this will effect the currents and voltages involved.

Remember this is a technical venue so avoid being vague or ambiguous.

Tips, Buy me a coffee, or three.. PayPal Venmo
Up vote any posts that you find helpful, it shows what's working..

VShah.4 · ‎2022-03-22

Yes I want to drive a GPIO pin as an input and know the minimum current for it?

VShah.4 · ‎2022-03-22

I want to know regarding STM32F401 GPIO pin. How much minimum current will be required to drive the pin as input?

VShah.4 · ‎2022-03-22

Thanks Paul.

It would be great if you can tell me about that specific value of input current(negligible as mentioned), or any method to find it.