Vishay TEPT4400 Phototransistor Ambient Light Sensor

The Vishay TEPT4400 is a high-performance, leaded silicon NPN epitaxial planar phototransistor, housed in a compact and industry-standard T-1 package. Designed to replicate the sensitivity of the human eye, this ambient light sensor is perfectly tuned to the visible spectrum, with a peak sensitivity at the optimal wavelength of 570nm. It serves as a reliable, modern replacement for older cadmium sulphide (CdS) photoresistors, offering superior performance and consistency.

A key application for this sensor is in automatic backlight dimming control. It is widely used to intelligently adjust the brightness of LCD displays and keypad backlights in mobile devices, helping to conserve battery life and improve user comfort. In industrial settings, it provides a robust solution for automated on/off lighting operations, contributing to energy efficiency and smart system control.

The component is characterised by its high photo sensitivity and a generous viewing angle, with an angle of half sensitivity of ±30°. It is built to operate reliably across a broad temperature range, from -40°C to +85°C, making it suitable for demanding environments. With a power dissipation rating of 100mW, it is an efficient choice for low-power electronic designs.

Key Specifications & Features

• High Photo Sensitivity: Detects visible light with performance akin to human vision.
• Peak Spectral Sensitivity: 570nm, ideal for ambient light measurement.
• Wide Viewing Angle: 60° total viewing angle (±30° half sensitivity).
• Robust Operating Range: Functions from -40°C to +85°C.
• Low Power Consumption: Power dissipation of 100mW.
• Compact Package: Industry-standard T-1 (3mm) case style.
• Lead Configuration: Simple 2-pin design for easy integration.

This Vishay phototransistor is an essential component for designers and engineers in consumer electronics and