Enter a sine-wave output voltage and frequency to find the required op amp slew rate, or work backward from a datasheet slew rate.
Advanced options
This is the minimum ideal sine-wave slew rate before any added design margin. Check the datasheet conditions and other limits separately.
This is the ideal full-power limit from slew rate and peak output voltage. Small-signal bandwidth may impose a lower limit.
This is the largest ideal sine-wave output allowed by the entered slew rate and frequency.
Use this value to confirm that Vpk, Vpp, or Vrms was interpreted as intended.
Table of contents
How to use our Op Amp Slew Rate Calculator
- Choose the question you need in "What do you want to find?"
- For a new voltage entry, first choose Vpk, Vpp, or Vrms in "Output voltage is measured as", then enter the required op amp output voltage after circuit gain.
- For a new frequency entry, first choose "Frequency unit", then enter the output sine-wave frequency from your requirement, generator, or measurement.
- For "Maximum sine-wave frequency" or "Maximum output voltage", enter the applicable datasheet value in "Op amp slew rate (V/us)".
- Select "Calculate". Check "Peak voltage used in the equation" to make sure a Vpp or Vrms entry was converted as you intended.
- For a required slew-rate result, compare it with the part's rated slew rate under relevant datasheet conditions. Then check output swing, load current, bandwidth, settling, and stability separately.
Definitions
Slew rate (V/us): The fastest rate at which an op amp output voltage can change, measured in volts per microsecond.
Vpk: Peak voltage from zero volts to one positive or negative peak of a sine wave.
Vpp: Peak-to-peak voltage from the negative peak to the positive peak. For a symmetric sine wave, Vpp is twice Vpk.
Vrms: Root-mean-square voltage. For a sine wave, Vpk equals Vrms times the square root of 2.
Full-power frequency: The ideal highest sine-wave frequency allowed by a stated slew rate and peak output voltage. It is different from small-signal bandwidth.
Common mistakes and quick fixes
Mistake: Entering the input signal voltage instead of the voltage required at the op amp output.
Fix: Enter the output waveform voltage after the circuit's gain.
Mistake: Entering a Vpp or Vrms value while "Output voltage is measured as" is set to Vpk.
Fix: Select the voltage form shown by the source, then check the displayed peak voltage used in the equation.
Mistake: Treating maximum sine-wave frequency as small-signal bandwidth.
Fix: Treat it only as an ideal slew-rate limit for the entered output amplitude. Check bandwidth and gain-bandwidth limits separately.
Mistake: Changing a unit alone to correct a number entered under the wrong unit.
Fix: Choose the correct unit, then re-enter the original source number. Changing units after a valid entry converts the number to preserve the same physical signal.
Limitations & Key Assumptions / Boundary Conditions
- These equations apply to sine-wave outputs. They do not predict edge speed for square waves, pulses, or other waveforms.
- Meeting the calculated slew-rate limit does not prove adequate output-voltage swing, load current, bandwidth, settling, phase margin, thermal behavior, or distortion performance.
- Use a slew-rate specification measured under conditions relevant to your supply voltage, load, output amplitude, temperature, and device version. Circuit results can differ from a datasheet test setup.
- The calculator uses the requested output waveform after circuit gain. It does not calculate circuit gain or add a design margin.
Methodology
Sine-wave calculation
A sine wave changes voltage fastest as it crosses zero. The calculator uses that maximum output-voltage slope.
SR (slew rate in V/us) = 2π x f (frequency in Hz) x Vpk (peak voltage in V) / 1,000,000
For example, a 20 kHz sine wave at 4 Vpp has a peak voltage of 2 V. The required slew rate is 2π x 20,000 x 2 / 1,000,000 = 0.251327... V/us.
Voltage conversion
The sine-wave equation needs peak voltage, so the calculator converts Vpp and Vrms entries before calculating.
Vpk = Vpp / 2
Vpk = Vrms x √2
Working backward from slew rate
For the inverse tasks, the calculator rearranges the same relationship.
fmax (Hz) = SR (V/us) x 1,000,000 / (2π x Vpk)
Vpk,max (V) = SR (V/us) x 1,000,000 / (2π x f (Hz))
Maximum frequency requires a peak voltage above zero. Maximum output voltage requires a frequency above zero. For the voltage task, the final peak-voltage limit is converted into the selected Vpk, Vpp, or Vrms form.