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TCA9539-Q1: Iq

Part Number: TCA9539-Q1

Hi expert,

I checked from datasheet, when I/O=input and no load, Iq as below. My question is that if I/O=output and the output level is low or high voltage, I/O connects to NMOS Gate pin. What is the Iq in this condition? 

Does Iq will be different when I/O=high/low level? 

Ethan Wen

  • Hi Ethan, 

    In theory, yes. There is extra current requirements needed in order to drive the I/O NMSO gates. However, this will be a very small addition in relation to the potential current draw from any connected load. Whenever an output port is driving the state of a populated net, there will be some leakage path where current will flow. In the majority of cases, this current will far exceed the needs of an IC's internal gate. The primary reason for specifying this current with the I/O configured as inputs was to ensure there was no current flowing to/from such a load connected to the I/O pins. This is why we recommend any unused pin or inactive output be configured as an input in order to save power. 

    Is this question pertaining to some desired use case for this device? If so, please share more details if possible as I'm interested where such a differentiation would need to be considered. 

    Eric Schott