CA3059

The CA3059 and CA3079 zero-voltage switches are monolithic silicon integrated circuits designed to control a thyristor in a variety of AC power switching applications for AC input voltages of 24V, 120V, 208/230V, and 277V at 50Hz-60Hz and 400Hz. Each of the zero-voltage switches incorporates 4 functional blocks (see the Functional Block Diagram) as follows:

1. Limiter-Power Supply - Permits operation directly from an AC line.

2. Differential On/Off Sensing Amplifier - Tests the condition of external sensors or command signals. Hysteresis or proportional-control capability may easily be implemented in this section.

3. Zero-Crossing Detector - Synchronizes the output pulses of the circuit at the time when the AC cycle is at zero voltage point; thereby eliminating radio-frequency interference (RFI) when used with resistive loads.

4. CA3059 Triac Gating Circuit - Provides high-current pulses to the gate of the power controlling thyristor.

In addition, the CA3059 provides the following important auxiliary functions (see the Functional Block Diagram).

1. CA3059 A built-in protection circuit that may be actuated to remove drive from the triac if the sensor opens or shorts.

2. Thyristor firing may be inhibited through the action of an internal diode gate connected to Terminal 1.

3. CA3059 High-power dc comparator operation is provided by overriding the action of the zero-crossing detector. This is accomplished by
connecting Terminal 12 to Terminal 7. Gate current to the thyristor is continuous when Terminal 13 is positive with respect to Terminal 9.

The CA3059 and CA3079 are supplied in 14 lead dual-inline plastic packages.