Hall-Effect Current Sensor Calculator
Calculate signed current, output voltage, zero-current offset, sensitivity, calibration references, ADC resolution and tolerance range for linear analog Hall-effect current sensors.
SEN-004 focuses on the Hall sensor transfer function. Shunt current sensing, current-transformer behavior, Rogowski coils and full ADC front-end design remain separate engineering scopes.
Engineering tool
Hall-Effect Current Sensor Calculator
Calculate analog Hall-effect current sensor output, signed current, zero-current offset, mV/A sensitivity, calibration, range, ADC resolution reference and tolerance corners.
Calculation mode
Parameter panel
Result console
- Current
- 5 A
- Current Magnitude
- 5 A
- Direction
- Positive Current
- Voltage Difference
- 500 mV
- Sensitivity
- 100 mV/A
Current sign is preserved. Do not take the absolute value unless the application truly needs magnitude only.
Hall current sensor formula audit
| Adopted Linear Model | VOUT = VZERO + S × I. |
|---|---|
| Current Polarity Convention | Positive current increases output when polarity is positive; inverted polarity reverses the sign. |
| Zero-Current Voltage | VZERO is the output voltage at zero current and does not have to be 0 V. |
| Sensitivity Definition | S is output-voltage slope in volts per ampere. |
| Sensitivity Units | µV/A, mV/A and V/A are converted internally to V/A. |
| Voltage to Current | I = (VOUT - VZERO) / S. |
| Current to Voltage | VOUT = VZERO + S × I. |
| Zero Offset | ΔVZERO = VZERO,measured - VZERO,nominal. |
| Equivalent Offset Current | IOFFSET = ΔVZERO / S. |
| Single-Point Sensitivity | S = (VOUT - VZERO) / I; I must not be zero. |
| Two-Point Calibration | S = (V2 - V1)/(I2 - I1), VZERO = V1 - S×I1. |
| Current Range Model | Range mode evaluates the linear output at Imin and Imax. |
| Supply Boundary | Out-of-range outputs are reported, not clamped. |
| ADC Reference | VLSB = VFS/2^N and ILSB = VLSB/|S×G|. |
| Tolerance Corner Model | VOUT, VZERO and S min/max corners are enumerated. |
| Temperature Boundary | Optional drift output is a linear reference, not a full temperature model. |
| Ratiometric Boundary | Use datasheet sensitivity and zero values at the actual supply voltage. |
| Bandwidth / Isolation Boundary | Bandwidth and isolation ratings must come from the device datasheet. |
Formula reference
Hall-Effect Current Sensor Formulas
The calculator uses a linear analog Hall current-sensor model with explicit zero-current voltage, signed sensitivity and current polarity.
VOUT = VZERO + S × II = (VOUT - VZERO) / SΔVZERO = VZERO,measured - VZERO,nominalIOFFSET = ΔVZERO / SS = (V2 - V1)/(I2 - I1)VZERO = V1 - S × I1VLSB = VREF / 2^NILSB = VLSB / |S × G|Variable definitions
- VOUT
- measured Hall sensor output voltage
- VZERO
- zero-current output voltage
- S
- signed sensitivity in volts per ampere
- I
- signed sensed current
- VLSB
- ADC voltage represented by one code
- G
- optional analog gain after the sensor
Hall Formula Audit
| Adopted Linear Sensor Model | VOUT = VZERO + S × I. |
|---|---|
| VOUT Definition | Analog output voltage measured at the Hall sensor output pin. |
| VZERO Definition | Output voltage at zero sensed current. |
| Current Definition | Signed sensed current in amperes. |
| Sensitivity Definition | Output voltage slope in volts per ampere. |
| Sensitivity Units | µV/A, mV/A and V/A are converted to V/A internally. |
| Polarity Model | The UI uses sensitivity magnitude plus positive or inverted polarity. |
| Voltage to Current | I = (VOUT - VZERO) / S. |
| Current to Voltage | VOUT = VZERO + S × I. |
| Current Polarity | Output above or below VZERO maps to signed current depending on polarity. |
| Zero Offset | Zero-current error is measured VZERO minus nominal VZERO. |
| Equivalent Offset Current | IOFFSET = ΔVZERO / S. |
| Single-Point Sensitivity | S = (VOUT - VZERO) / I; I must not be zero. |
| Two-Point Calibration | S = (V2 - V1)/(I2 - I1), VZERO = V1 - S×I1. |
| Current Range | The calculator evaluates output voltage at current minimum and maximum. |
| Supply Range Boundary | Output predictions outside 0 V to supply voltage are flagged, not clamped. |
| ADC Reference | VLSB = VREF/2^N and ILSB = VLSB / |S × gain|. |
| Tolerance Model | Measured voltage, zero voltage and sensitivity corners are enumerated. |
| Temperature Drift Boundary | Temperature drift is reported as a linear reference, not a complete device model. |
| Ratiometric Boundary | Use datasheet zero and sensitivity values at the actual supply/reference condition. |
| Bandwidth Boundary | Bandwidth and isolation limits must come from the sensor datasheet. |
| Shunt Boundary | This page does not calculate shunt resistor voltage drop or dissipation. |
Worked Examples
Voltage to current
Known: VOUT=3.0 V, VZERO=2.5 V, S=100 mV/A
I=(3.0-2.5)/0.1=5 A.
Negative current
Known: VOUT=2.0 V, VZERO=2.5 V, S=100 mV/A
I=-5 A with positive polarity.
Inverted sensor polarity
Known: VOUT=2.0 V, VZERO=2.5 V, S=100 mV/A inverted
Signed sensitivity is -0.1 V/A, so I=5 A.
Current to voltage
Known: I=10 A, VZERO=2.5 V, S=100 mV/A
VOUT=3.5 V.
Negative current to voltage
Known: I=-10 A, VZERO=2.5 V, S=100 mV/A
VOUT=1.5 V.
Zero offset current
Known: Nominal VZERO=2.5 V, measured VZERO=2.52 V, S=100 mV/A
Offset current is 0.2 A.
Single-point sensitivity
Known: I=5 A, VOUT=3.0 V, VZERO=2.5 V
S=0.1 V/A = 100 mV/A.
Two-point calibration
Known: (-5 A, 2.0 V) and (5 A, 3.0 V)
S=100 mV/A and VZERO=2.5 V.
Range check
Known: I=-10 A to 10 A, VZERO=2.5 V, S=100 mV/A
Output range is 1.5 V to 3.5 V.
Supply boundary
Known: Same range on a 3.3 V output rail
3.5 V exceeds the ideal supply range and is flagged.
ADC LSB
Known: 12-bit ADC, 3.3 V reference
VLSB=805.7 µV.
ADC current resolution
Known: VLSB=805.7 µV and S=100 mV/A
Current per LSB is about 8.06 mA.
Analog gain reference
Known: Gain=2 after the sensor
Effective sensitivity doubles and current per LSB halves.
mV/A conversion
Known: 100 mV/A
Internal sensitivity is 0.1 V/A.
µV/A conversion
Known: 1000 µV/A
Internal sensitivity is 0.001 V/A.
Ratiometric midpoint
Known: 5 V supply bidirectional sensor
Nominal VZERO is often near 2.5 V.
3.3 V ratiometric midpoint
Known: 3.3 V supply bidirectional sensor
Nominal VZERO is often near 1.65 V.
Tolerance corner
Known: VOUT=3.0 V, VZERO=2.5 V, S=100 mV/A, ±1% S
Current range is computed from actual voltage and sensitivity corners.
Temperature offset
Known: Offset drift 1 mV/°C over 10°C
Zero reference shifts by 10 mV, equal to 0.1 A at 100 mV/A.
Round trip
Known: I=7.3 A -> VOUT -> I
The linear model recovers 7.3 A before nonideal effects.
Zero-current sensitivity invalid
Known: I=0 A at a single point
Sensitivity cannot be solved from a zero-current measurement.
Out-of-range not clamped
Known: Predicted VOUT below 0 V
The calculator reports the ideal value and warning instead of hiding the fault.
Engineering Notes
| Hall-Effect Current Sensor | A Hall sensor converts conductor magnetic field into an analog voltage proportional to current. |
|---|---|
| Linear Output | Many integrated Hall current sensors are specified with VZERO and mV/A sensitivity. |
| Zero-Current Voltage | Bidirectional devices commonly use mid-supply output at zero current. |
| Sensitivity | Sensitivity is a slope. Always convert mV/A or µV/A to V/A before current math. |
| Current Polarity | Preserve current sign when direction matters for charging, motor drive or bidirectional supplies. |
| Bidirectional Measurement | Output can move above or below VZERO to represent opposite current directions. |
| Unidirectional Measurement | Some devices only cover one current direction and may use a different zero reference. |
| Ratiometric Output | If the output is ratiometric, ADC reference and sensor supply choices can affect apparent readings. |
| Output Swing | The linear equation does not guarantee the output amplifier can reach the calculated voltage. |
| Supply Voltage | Supply voltage does not directly enter the ideal transfer equation unless it changes VZERO or sensitivity. |
| ADC Resolution | ADC LSB size sets the smallest ideal output-voltage step, not the full measurement uncertainty. |
| Noise | Sensor noise and ADC noise often dominate low-current readings. |
| Offset Drift | Zero-current voltage can drift with temperature, time and magnetic history. |
| Sensitivity Tolerance | Datasheet sensitivity tolerance should be included in current error budgets. |
| Temperature Drift | Offset and sensitivity drift should be evaluated over the actual operating temperature range. |
| Bandwidth | Bandwidth limits dynamic current measurement and ripple accuracy. |
| Isolation | Isolation voltage and creepage are datasheet and layout requirements, not linear-equation results. |
| Magnetic Saturation | Core or magnetic concentrator saturation can break the ideal linear model. |
| External Fields | Nearby magnetic fields can introduce measurement error. |
| Calibration | Zero and span calibration improve electrical transfer accuracy but cannot remove every nonideal effect. |
Common Mistakes
- Forgetting zero-current output voltage and treating 0 V as zero current.
- Confusing mV/A with A/mV.
- Ignoring current polarity.
- Using a signed sensitivity entry and a polarity switch at the same time.
- Assuming output can swing below ground or above the supply rail.
- Ignoring zero-current offset drift.
- Ignoring sensitivity tolerance.
- Treating ADC resolution as total accuracy.
- Using a 5 V datasheet zero value with a 3.3 V ratiometric setup.
- Ignoring bandwidth when measuring switching-current ripple.
- Assuming Hall sensors behave like shunt resistors.
- Ignoring isolation and creepage requirements.
- Ignoring external magnetic fields.
- Calibrating at one current point and assuming temperature behavior is solved.
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FAQ
What is a Hall-effect current sensor?
A Hall-effect current sensor measures magnetic field produced by conductor current and converts it to an electrical output voltage.
How do I calculate current from Hall sensor voltage?
Subtract the zero-current output voltage from the measured output voltage, then divide by sensitivity in volts per ampere.
How do I calculate Hall sensor output voltage?
Use VOUT = VZERO + S × I, where S is the signed sensitivity and I is current.
What does mV/A mean?
mV/A means millivolts of output voltage change per ampere of sensed current.
What is zero-current output voltage?
Zero-current output voltage is the sensor output when the measured current is zero.
Why is zero-current output often half the supply voltage?
Bidirectional Hall sensors often use a mid-supply zero point so positive and negative currents can move the output in opposite directions.
Can Hall sensors measure negative current?
Bidirectional Hall sensors can represent current polarity when the output is above or below the zero-current reference.
How do I calibrate a Hall current sensor?
Measure the output at zero current for offset, then measure one or more known currents to estimate sensitivity and polarity.
How do I calculate sensitivity from two measurements?
Use S = (V2 - V1)/(I2 - I1) with two different known current values.
How does zero offset affect measured current?
Zero voltage error appears as an equivalent current error equal to the zero voltage error divided by sensitivity.
How does sensitivity tolerance affect accuracy?
Sensitivity tolerance changes the voltage-to-current slope, so the same voltage difference maps to a range of possible current values.
How do I calculate current resolution with an ADC?
Divide ADC voltage per LSB by the effective Hall sensitivity after any analog gain.
How does temperature affect Hall sensors?
Temperature can shift zero-current output and sensitivity. Datasheet drift specifications should be included in an error budget.
What does ratiometric output mean?
A ratiometric sensor output scales with supply voltage, so zero-current voltage and sensitivity should be evaluated at the same supply and ADC reference context.
What limits Hall sensor bandwidth?
Internal signal conditioning, magnetic core behavior, package construction and external filtering can limit bandwidth.
What is the difference between Hall sensing and shunt-resistor current sensing?
Hall sensing is magnetic and can provide isolation. Shunt sensing measures voltage drop across a resistor and is handled by different circuit assumptions.
Engineering Disclaimer
This calculator provides ideal linear Hall-effect current sensor arithmetic. Critical current sensing designs require datasheet review, isolation and creepage checks, output swing verification, magnetic layout review, ADC input analysis, bandwidth validation, calibration and measurement under real operating conditions.