Device Operation

NVE Corporation

(952) 829-9217

iso-apps@nve.com

www.IsoLoop.com

www.nve.com

IL600-Series Isolators are current mode devices. Changes in current flow into the input coil

drive output logic state changes.

The output is high with no signal present. Current flow from In- to In+ switches the output

low. The worst-case logic low threshold current is 5 mA. An input current of at least 8 mA

ensures fail-safe operation, meaning the output powers up in the correct state. The absolute

maximum coil current is 25 mA.

The evaluation board has examples of inputs configured as inverting and non-inverting:

For single-ended operation (that is, the coil current does not reverse), a boost capacitor in

parallel with the current-limiting resistor is used to induce bidirectional coil current. For

standard logic signals with rise times less than 10 ns,

a 16 pF boost capacitor is recommended. The

capacitor should be larger for slower rise time inputs.

The isolators can also be used with differential inputs

as shown in the figure at right. No boost capacitor is

needed if the coil current reverses in this

configuration. Unlike optocouplers, the input current

can be negative without reverse bias protection.

There is no limit to the input voltage as long as the

input current is limited.

+V

V

DD

GND

1

GND

2

-

+

GND

1

2

C

boost

R

limit

+V

V

DD2

GND

1

GND

2

-

+

R

limit

C

boost

GND

1

2

Inverting Configuration

Non-inverting Configuration

+V

V

DD

GND

1

GND

2

-

+

GND

1

2

R

limit

Differential Configuration