Pull-up resistor
Also: bias resistor
A resistor that gives a signal a default high level when nothing drives it low.
Its resistance trades low-state current against RC rise time, leakage tolerance, and noise susceptibility.
- Formula
I_low ≈ V_pullup/R
Example 3.3 V through 10 kΩ draws 0.33 mA when grounded.
Common misconception A pull-up is not a power supply for loads and internal pull-ups are often loosely specified.