Spark Logic

ACS712 Hall-effect current sensor connection guide

ACS712 Hall-effect current sensor LC SOIC-8 wiring guide with power, signal assignments, and bench checks.

LC SOIC-8

8 contacts Current package

Allegro MicroSystems · Allegro LC, 8-lead narrow small-outline package.

Measure the zero-current output

Required

Power the signal side from 5 V. Leave the primary path open for the zero reading.

C1 100 nF between 5 V and Signal return5 VC1 100 nFSignal return
CF 47 nF between Bandwidth setting and Signal returnBandwidth settingCF 47 nFSignal return

Bench checks

  • Read VIOUT relative to GND on a high-impedance meter. A healthy nominal unit sits near 2.5 V at zero current.

Allegro ACS712-DS Rev. 22, typical application and zero-current characteristics

Connection scenarios

Measure a known DC current

Use an independent, current-limited 5 V source for the primary circuit. A 10 Ω, 5 W resistor limits its current to approximately 0.5 A.

C1 100 nF between 5 V and Signal return5 VC1 100 nFSignal return
CF 47 nF between Bandwidth setting and Signal returnBandwidth settingCF 47 nFSignal return
RL 10 Ω / 5 W between Primary load and Primary returnPrimary loadRL 10 Ω / 5 WPrimary return

Bench checks

  • Measure voltage across RL and divide by its measured resistance to obtain the reference current.
  • Subtract the zero reading. At 0.5 A the expected change is about +92.5, +50 or +33 mV for 05B, 20A or 30A respectively.

Allegro ACS712-DS Rev. 22, typical application and sensitivity tables. The bench load is chosen for this test.

LC SOIC-8 wiring map

Highlighted contacts are used in the required step or selected circuit. Select a contact to inspect it.

Top view. Locate the package index before counting counterclockwise from pin 1.
Selected pin details

8 · VCC

Supply · Power

Nominal 5 V supply. Bypass near this lead to GND.

Allegro ACS712-DS Rev. 22, pinout diagram

Electrical limits · Pin in the reference

Models and documents

The LC-package sensing ranges share one terminal map. Match the exact suffix before converting voltage to amperes.

ACS712ELCTR-05B-T
±5 A optimized range, 185 mV/A typical at 5 V and 25 °C.
ACS712ELCTR-20A-T
±20 A optimized range, 100 mV/A typical at 5 V and 25 °C.
ACS712ELCTR-30A-T
±30 A optimized range, 66 mV/A typical at 5 V and 25 °C.
ACS712ELCTR-20A-S
±20 A optimized range, 100 mV/A typical at 5 V and 25 °C.
ACS712ELCTR-30A-S
±30 A optimized range, 66 mV/A typical at 5 V and 25 °C.
  • Allegro ACS712-DS Rev. 22· Selection guide, package drawing, terminal functions and sensitivity tables.
  • Source register· Document revisions, applicable order codes, consulted sections and available file checksums.