Use this electronics calculation for a first-pass component, converter, signal, motor, or sensor estimate when the stated operating conditions and units match the device data.

VDD (V)

Required number input.

Maximum output low voltage (V)

Optional number input.

Sink current (mA)

Optional number input.

Compute the minimum I2C pull-up resistance from VDD, the maximum output low voltage, and the sink current. The tool evaluates the supplied inputs together and returns the named outputs below; it does not infer omitted operating conditions or change the units shown.^[1]

Minimum pull-up resistance (Ω)

The resulting minimum pull-up resistance returned as a number.

• I²C pull-up and capacitance estimates depend on supply voltage, logic thresholds, sink-current limits, rise-time mode, trace and device capacitance, level shifters, topology, and bus speed. Confirm the complete bus against the applicable I²C timing specification and every device datasheet.
• Use finite inputs in the displayed units and preserve more precision than the final presentation requires. Independently verify safety-critical, financial, compliance, or production decisions.

Check the result against the current datasheet and worst-case operating corners, then verify the circuit or measurement with simulation and bench testing where failure matters.

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