ST0947 Type A 4.5~5.5V Low-Power Residual Current Protection IC

Overview

The ST0947 is a high-performance Type A residual current protection IC designed to detect Type A (including AC type) leakage signals, handling both sinusoidal AC and pulsating DC residual currents. It integrates a voltage regulator, amplifier circuit, comparator circuit, delay circuit, trip control circuit and SCR driver circuit; combined with an external trip coil and power supply circuit, it achieves complete leakage protection functionality. When leakage occurs, the leakage signal is detected through a zero-sequence current transformer (ZCT) whose secondary coil output serves as the IC input; once a leakage signal is detected, the TRIG pin outputs a pulse wider than 20ms, driving the SCR directly. With a positive operating voltage of 3~5mV (VDD=5V) and a typical quiescent current of only 260µA, the operating delay can be flexibly adjusted via an external capacitor on the DLY pin, and only simple resistors and capacitors are needed for a typical application. Offered in a SOP-8L package over a -40~+85℃ operating range, the ST0947 provides a highly consistent leakage protection solution covering both Type A and AC-type signals for low-voltage distribution, household appliances and industrial control equipment.

Features

• Suitable for detecting Type A (including AC type) leakage signals
• TRIG outputs a pulse width greater than 20ms upon detection and can directly drive the SCR
• Consistent tripping accuracy for different types of leakage signals
• Good electromagnetic interference protection capability
• Suitable for 110V~220V (50Hz~60Hz) voltage
• Adjustable operating delay (external capacitor on DLY; 9~15ms with 330nF)
• Low quiescent current: typ 260µA (VDD=5V)
• Positive operating voltage 3~5mV (VDD=5V); output latch duration 20~40ms
• SOP-8L package, -40~+85℃ operating temperature

Typical Applications

• Low-voltage distribution equipment
• Household appliances
• Industrial control equipment