What value of pull-up resistor do I need when using an open-drain output?

Description

An open-drain output will drive either a low state '0', or high-impedance state 'Z'. When the output is in a high-impedance state, an external pull-up resistor provides a passive pull-up to the high '1' level.

In determining what value of resistor to select for your open-drain output, a design trade-off needs to be considered. Using a smaller resistor will give fast rising edges, but will produce a high DC current when the output is driving low. A larger resistor will minimize the DC current when the output is driving low and give a faster falling edge, but will have a slower rising edge on the signal.

The typical values selected for open-drain outputs are between 1 KΩ and 5 KΩ resistors.