ACT001-10E Isolated Current Sensor

NVE Corporation

•

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

•

(952) 829-9217

•

www.nve.com

Overcurrent Switch with Hysteresis

Hysteresis can be added to a single- comparator overcurrent circuit to minimize spurious switching:

Figure 5. Overcurrent comparator circuit with hysteresis.

Three additional resistors set the hysteresis, which is equal to (R3/2R4) / Sensitivity.

Power Sensor

Since the sensor output is ratiometric with the power supply, the ACT001 can be used as a power sensor with

no additional components and no multiplication required:

Figure 6. Power sensor.

The sensor output is proportional to both the motor voltage and the motor current, so the sensor output is

proportional to power. Since the sensor has no active elements, it is accurate down to zero supply voltage.

+

-

ACT001

+

-

NCS

2200

R1 (

40 k)

2x

0.8 V

5.5 V

Comparator

Output

Current

200 mA

Threshold = R1

/R2 /

Rb = Sensor Bridge Resistance

Hysteresis = (R3/2R4) / Sensitivity

[(

+Rb/2)

] Sensitivity

R2

(5 M )

47

pF

2x 2

10 M )

R2

(

50 mA

R

(

4

10 M )

R

(

3

50 k)

Sensor

VDD

GND

I+

I-

OUT+

OUT-

Motor

VOUT+ – VOUT-

VDD x

I

= Power