PT8A2645WEX

Sensor And Detector Interfaces Overview

The PT8A2645WEX is a CMOS LSI PIR sensor light switch controller designed for automatic lamp control. It operates at a typical voltage of 5V with an average supply current of 120µA. The device features a two-stage operational amplifier, a built-in noise rejection circuit, and an on-chip regulator providing approximately 3.6V. It supports AC 220V/50Hz and 110V/60Hz applications. The chip includes a zero-crossing detector, system oscillator, and output timing oscillator. It offers selectable operating modes (ON/AUTO/OFF) via the MODE pin and provides pulse outputs to drive triacs.

Sensor And Detector Interfaces Feature Summary

• Supports both two-wire triac configurations and three-wire relay configurations.
• Includes adjustable output duration controlled by external RC components.
• Features day/night auto-detection using a CDS input with debounce filtering.
• Provides override functionality allowing manual switching between ON and AUTO modes.

Sensor And Detector Interfaces Applications

• Automatic PIR lamp control systems
• AC 220V/50Hz lighting circuits
• AC 110V/60Hz lighting circuits

Sensor And Detector Interfaces Procurement Notes

Verify the specific ordering suffix 'W' corresponds to the 16-Pin SOIC package and 'E' indicates lead-free status as per Diodes Incorporated documentation. Confirm availability directly with the manufacturer or authorized distributors, as some variants in this series may require special contact for stock verification. Ensure the component matches the exact part number PT8A2645WEX for correct pinout and functional compatibility.

Sensor And Detector Interfaces Selection Notes

Select the PT8A2645WEX when a pulse output is required to drive a triac rather than a direct relay drive. This variant is suitable for two-wire PIR detector applications. Ensure the design accommodates the 40-second warm-up period and utilizes external RC networks on the OSCD and OSCS pins to set the desired timer frequency and system clock respectively.

Sensor And Detector Interfaces Part Context

The PT8A2645WEX belongs to the PT8A264X family of PIR sensor light switches manufactured by Diodes Incorporated (formerly Pericom). This family integrates analog front-end processing with digital control logic for motion-sensing lighting. The '2645' designation specifically identifies the version optimized for triac driving applications within the broader product line.

Sensor And Detector Interfaces Replacement Considerations

PT8A2641WEX serves as a functional substitute within the same series, sharing identical pinouts and core control logic for triac-based applications. Both parts utilize the 16-pin SOIC package and support the same operating modes and electrical characteristics defined in the datasheet.

Sensor And Detector Interfaces FAQ

What is the default operating mode upon power-up?

When the MODE pin is left open, the chip defaults to AUTO mode, where outputs remain off until activated by a valid PIR trigger signal.

How is the output duration adjusted?

The output duration is determined by an external RC network connected to the OSCD pin. The minimum resistor value should be low enough (around 2K) to provide a wide adjustment range.

What happens if the ZC signal disappears for more than 3 seconds?

If the zero-crossing signal is absent for over 3 seconds, the chip automatically restarts the initialization operation, which lasts for 40 seconds.