Timer IC Calculator
Calculate timing component values for a monostable timer pulse.
About Timer IC Calculator
The monostable pulse width depends only on R and C, not on supply voltage, because the threshold is a fixed fraction of supply. The 1.1 factor comes from the natural logarithm of 3. Retriggering before the pulse ends produces unpredictable timing, so the maximum trigger rate must leave margin beyond the pulse width.
Formula
Timer IC
t = 1.1 R C for a monostable timer
- 1.1
- Constant from the two-thirds supply threshold of the timing comparator
Worked example
With the default values below, Timer IC Calculator returns Pulse Width of 1,100.0000. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Timing resistanceminimum 0.01 ohm
- 100,000 ohm
- Timing capacitanceminimum 0 F
- 0.00001 F
- Target pulse widthminimum 0.001 ms
- 1,000 ms
Results
- Pulse Width
- 1,100.0000 ms
- Pulse Width
- 1.100000 s
- Resistance for the Target Width
- 90,909.09 ohm
- Capacitance for the Target Width
- 0.000009090909 F
- Maximum Retrigger Rate
- 0.7576 Hz
Step by step
- 1Values used
- 2Timer IC
- 3Pulse Width= 1,100.0000 ms
- 4Pulse Width= 1.100000 s
- 5Resistance for the Target Width= 90,909.09 ohm
- 6Capacitance for the Target Width= 0.000009090909 F
- 7Maximum Retrigger Rate= 0.7576 Hz
Assumptions and limits
- The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to 12 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
How is Timer IC calculated?
t = 1.1 R C for a monostable timer The monostable pulse width depends only on R and C, not on supply voltage, because the threshold is a fixed fraction of supply. The 1.1 factor comes from the natural logarithm of 3.
Why does Timer IC matter?
Retriggering before the pulse ends produces unpredictable timing, so the maximum trigger rate must leave margin beyond the pulse width.
What values do I need to enter?
This calculator takes 3 inputs: Timing resistance, Timing capacitance, Target pulse width. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.