Optically-coupled isolator uses lower current

UK opto-electronic component specialist Isocom Components announces a low-current, high gain, optically-coupled isolator based on the industry standard 4N32 photo Darlington type

UK opto-electronic component specialist Isocom Components announces the availability of a low-current, high gain, optically-coupled isolator based on the industry standard 4N32 photo Darlington type, with additional sensitivity.

Using the latest manufacturing and quality control techniques, the drive current has been reduced considerably to guarantee a consistent performance.

Standard 4N32 types are normally specified for forward currents of 10mA or more, but Isocom Components' 4N32-1 produces a guaranteed current transfer ratio (CTR) of 800 for a drive current of only 1mA.

Furthermore, in its most sensitive 4N32-3 version, an input as low as 0.25mA consistently produces a CTR of no less than 200%.

The power-saving isolator is available in a compact six-pin, dual-in-line plastic package, available with a standard or 10mm G-form lead spread, or gull-wing configured for surface mounting.

Within the package, an infra-red LED couples optically with an NPN photo-transistor pair to create a 5kVr.m.s.

proof galvanic isolation barrier between diode input and photo Darlington output.

The transistors' Darlington arrangement allows the device to achieve a typical CTR figure in excess of 1000 for an input current in the order of 1mA.

In addition, the six-pin format with a base connection makes it possible to provide a base pin through which to fine-tune the CTR level and output rise time.

As well as its power saving low current requirements, the 4N32-3,-2,-1 has been designed to work reliably at a saturation level of only one volt to simplify circuit requirements, although its collector-emitter breakdown voltage has still been kept high at 55V.

The isolator will operate over a temperature range of -55oC to +100oC.

These optically-coupled isolators are used to maintain isolation between system components, eliminate the problems caused by ground loops, and facilitate signal transmission between systems of different potential and impedance.

They are used typically in computer terminals, industrial controllers and measuring instruments.

The low input current needs of the Isocom Components 4N32-3,-2,-1 can make a significant contribution to minimising the power requirement of a system, particularly when a number of isolators are involved.

Approval to the latest VDE 0884 safety standard makes the device ideal for incorporation into power supplies, CE marked products and systems where guaranteed high voltage isolation is essential.

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