Pull-up and pull-down design
Combine drive-current, leakage and capacitive transition limits to find a valid resistor interval.
Development preview. Check the assumptions below before relying on a result. Calculations run in your browser.
How it calculates
Model: Rmin=opposing voltage/(drive current−leakage); tr=RC ln[(0.7Vs−IleakR)/(0.3Vs−IleakR)]; Rmax also obeys the DC threshold bound.
Assumptions
- Interface presets select transition time only. Supply, capacitance, sink capability and threshold values remain user-entered and must match every attached device.
- Leakage is a constant worst-direction current. Both worst drive burden and leakage-shifted RC transition are checked; wiring inductance and active accelerators are not included.
Worked example
These are the calculator's default inputs. Change any input above to recalculate.
Inputs
- Passive bias
- pull-up
- Transition-time reference
- custom
- Supply
- 3.3 V
- Driver low-level bound
- 0.4 V
- Driver high-level bound
- 2.9 V
- Receiver minimum high
- 2.31 V
- Receiver maximum low
- 0.99 V
- Available sink/source current
- 0.003 A
- Total worst-direction leakage
- 0.000001 A
- Total node capacitance
- 1e-10 F
- Custom 30–70% transition limit
- 3e-7 s
- Candidate resistance
- 4700 Ω
Results
- Minimum resistance
- 966.989 Ω
- Maximum resistance
- 3532.15 Ω
- Candidate 30–70% transition
- 3.99509e-7 s
- Worst passive logic level
- 3.2953 V
- Candidate opposing-drive current
- 0.000618021 A
- Candidate driven-state loss
- 0.00178936 W
- Feasible interval
- A resistor interval exists