Current sense amplifier
Current sense amplifier with circuit equations and operating-limit checks.
Development preview. Check the assumptions below before relying on a result. Calculations run in your browser.
How it calculates
Shunt sizing: Rshunt = Vsense,FS/IFS
Output: Vout = Vref + G I Rshunt(T)
Worst-case input error: |Vos| + |Vsense|(gain tolerance + shunt tolerance) + |Vcm|/CMRR
Assumptions
- Generic specified-gain current-sense amplifier; bandwidth and CMRR are user-entered. High-side mode requires a part whose common-mode range includes the bus. Shunt heating is not solved self-consistently; temperature is entered. Thermal EMFs, offset drift and inductance are omitted.
Worked example
These are the calculator's default inputs. Change any input above to recalculate.
Inputs
- Placement
- low
- Measured current
- 5 A
- Full-scale current
- 10 A
- Full-scale shunt voltage
- 0.05 V
- Amplifier gain
- 50
- Output reference
- 0 V
- High-side bus voltage
- 12 V
- Input offset bound
- 0.00002 V
- Gain error
- 0.1 %
- Shunt tolerance
- 1 %
- Shunt tempco
- 50 ppm/°C
- Shunt temperature
- 75 °C
- CMRR
- 100 dB
- Closed-loop bandwidth
- 100000 Hz
Results
- Nominal amplifier output
- 1.25313 V
- Nominal shunt
- 0.005 Ω
- Actual shunt signal
- 0.0250625 V
- Shunt dissipation
- 0.125312 W
- Worst-case output error
- 0.0147906 V
- Worst-case current error
- 1.1803 %
- Input common mode
- 0.0125313 V