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THE FEUTEX TOOLKIT

I²C Pull-Up Resistance Window

Compare rise-time and sink-current limits for a bus pull-up.

Electronics workspace● Runs in your browser
01 Your input
02 Your result
View or copy raw result data
FormulaRmin=(VDD−VOL)/IOL; Rmax=tr/(0.8473 Cbus)
Sources and model references

Worked example

Inputs

Supply
3.3 V
Maximum low voltage
0.4 V
Guaranteed sink current
0.003 A
Allowed rise time
3e-07 s
Bus capacitance
1e-10 F

Expected results

Minimum resistance
966.6666667 ohm
Maximum resistance
3540.658562 ohm
Window width
2573.991896 ohm

Load the example in the workspace to reproduce these results. Display rounding does not change the underlying calculation.

How to use this tool

  1. Enter the labeled inputs in the indicated units.
  2. Calculate and compare every output against the stated model assumptions.

Try this example

{
  "s": 3.3,
  "vol": 0.4,
  "i": 0.003,
  "tr": 3e-7,
  "c": 1e-10
}

Accuracy and scope

Use limits from actual devices and operating mode; a negative window means these assumptions have no solution. Simplified analytical model; not a design recommendation or safety certification.

Is my data uploaded?

This tool runs locally in your browser. Input and output are not sent to a processing server. Copy or download your result before leaving the page.