ACT001-10E Isolated Current Sensor

NVE Corporation

•

11409 Valley View Road, Eden Prairie, MN 55344-3617

•

(952) 829-9217

•

www.nve.com

Differential Amplifier

An op-amp can be used to provide a single-ended amplified output. The circuit below has a gain of 20 for

full-scale at approximately the sensor’s maximum output. The potentiometer provides a positive offset so

negative currents still produce a positive output, and corrects the sensor’s offset. The 500 kΩ input resistors

are significantly higher than the sensor output impedance to avoid loading. The capacitor limits high-

frequency noise. The low-cost, low bias current op amp allows large resistors to avoid loading the sensor

bridge.

Figure 3. Differential amplifier circuit.

Overcurrent Switch

A comparator can be used to provide overcurrent detection:

Figure 4. Single-comparator overcurrent circuit.

The resistors set the switching threshold, which is equal to (R1/R2) / Sensitivity. The capacitor limits high-

frequency noise.

+

-

2.7-12V

500K

ACT001 Sensor

500K

TLV271

OUT-

OUT+

20(V

- V

)

OUT+

OUT-

10 M

10

M

VCC

GND

500K

Offset

47

pF

+

-

ACT001

0.8 V

5.5 V

+

-

NCS

2200

R1 (

100k )

2x

Comparator

Output

Current

200 mA

Threshold = (R1/R2) / sensitivity

R2

(10 M )

R2

(10 M )

47

pF