NTE914

Integrated Circuit

Zero–Voltage Switch

Description:

The NTE914 zero–voltage switch is a monolithic silicon integrated circuit in a 14–Lead DIP type pack-

age 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 50/60Hz and 400Hz. The NTE914 incorporates 4 functional

blocks as follows:

Limiter–Power Supply: Permits operation directly from an AC line.

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.

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.

TRIAC Gating Circuit: Provides high current pulses to the gate of the power controlling thyristor.

The NTE914 also provides the following important auxiliary functions:

A built–in protection circuit that may be actuated to remove drive from the TRIAC if the sensor

opens or shorts.

Thyristor firing may be inhibited through the acting of an internal diode gate connected to Pin1.

High–power DC comparator operation is provided by overriding the action of the zero–crossing

detector. This is accomplished by connecting Pin12 to Pin7. Gate current to the thyristor is

continuous when Pin13 is positive with respect to Pin9.

Features:

D 24V, 120V, 208/230V, 277V at 50Hz, 60Hz, or 400Hz Operation

D Differential Input

D Low Balance Input Current: 1µA Max

D Built–In Protection Circuit or Opened or Shorted Sensor

D DC Mode

D External Trigger

D External Inhibit

D DC Supply Voltage: 14V Max