TM4C1290NCPDT: GPIO input/output impedance

Dennis McGlumphy

I can find the pullup and pulldown resistance values for the GPIO pins but not the input/output impedance. Does anyone have this information? Thank you.

over 4 years ago

0 Charles Tsai over 4 years ago

TI__Guru**** 191886 points

Hi,

I hope this post will answer your question. The output impedance will depend on the load. However, you can calculate by dividing the Vol by the current sink. For example, the TM4C129 datasheet shows Vol = 0.4V. If the I/O is sinking 8mA then 0.4V/8mA is about 50ohm. Input impedance (Mohm range) will be very high when the pin is an input.

https://e2e.ti.com/support/microcontrollers/arm-based-microcontrollers-group/arm-based-microcontrollers/f/arm-based-microcontrollers-forum/905501/tm4c123bh6zrb-what-is-the-gpio-output-impedance-hi-z-mode-when-device-is-under-reset?tisearch=e2e-sitesearch&keymatch=tm4c129%2525252525252520gpio%2525252525252520impedance#

0 Dennis McGlumphy over 4 years ago

Expert 1390 points

Thank you for the quick response. I read your link below. My purpose in digital communication. Given the receiving input is a very high impedance input, I'm lead to believe the output impedance of the TIVA uC would be very high. Is this correct?

+1 Charles Tsai over 4 years ago in reply to Dennis McGlumphy

TI__Guru**** 191886 points

Hi,

No, the output impedance will be small like 50ohm per my explanation above. In an ideal circuit, the input impedance will be infinite while the output impedance will be 0.

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TM4C1290NCPDT: GPIO input/output impedance