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TCA8418 I2C Controlled Keypad pull-up resistors

Thomas Wesenberg
Prodigy 110 points

In another posting the use of additional pull-up resistors were mentioned to reduce wrong key recognition when the capacitive load is higher than usual.

But why is the use of pull-up resistors required if the pin is not used (pin functions table on page 3) ?

Table 'electrical characteristics' on page 5 states that there are already internal pull-ups of about 100kOhms.

  • 0
    TI__Genius 16510 points

    Thomas,

    This is not a hard requirement, because as you mentioned there is a programmable 100k pull up on the pins. However, it's typically good practice in the event that the programmable pull-up resistor is disabled, and then the pin would be floating.