Vishay Semiconductor Opto Division BPW85

Overview

BPW85 from Vishay Semiconductors is a silicon NPN phototransistor in a clear T-1 (Ø3 mm) plastic package, optimized for visible and near-infrared detection with peak sensitivity at 850 nm, 0.8–8 mA collector light current under 1 mW/cm² irradiance at 950 nm, ±25° half-sensitivity angle, and 2.0 µs turn-on time. It serves as a radiation-sensitive switch or analog detector in optocoupled feedback, position sensing, and ambient light monitoring circuits.

For engineers reviewing the BPW85 datasheet, BPW85 pinout, BPW85 application, or BPW85 equivalent, key selection criteria include radiant sensitivity range (450–1080 nm), angular response profile, dark current (<200 nA), spectral peak alignment with IR LEDs, and thermal derating behavior above 55 °C ambient.

Technical Context

The BPW85 operates as a two-terminal photosensitive NPN transistor-base is unconnected and illumination generates base current to control collector-emitter conduction. Its junction capacitance is 3 pF at 5 V, enabling >180 kHz bandwidth under 100 Ω load with 5 V supply.

It exhibits strong temperature dependence: collector light current drops to ~60% at 100 °C vs. 25 °C, while dark current rises exponentially-reaching ~10⁴ nA at 100 °C-necessitating bias stabilization in precision analog designs.

Key Specifications

Pinout & Package

Package: T-1 (Ø3.0 ± 0.1 mm) clear plastic leaded package with standard radial leads; body length 7.0 ± 0.3 mm, lead spacing 2.54 mm nominal.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar phototransistor applications.

Compared with TEPT5600 and QSE113, the BPW85 offers balanced sensitivity, directional selectivity, and cost-effective plastic packaging-making it optimal for general-purpose industrial and consumer optical sensing where moderate irradiance and defined angular response are design priorities.

Availability

BPW85 is available at Aetrix Electronics and suitable for optical encoder feedback, IR remote control receiver, industrial object detection, and light barrier safety systems requiring stable component supply across automotive, factory automation, and consumer electronics programs.

Supply support for BPW85 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Vishay Intertechnology is a global manufacturer of discrete semiconductors and passive components, specializing in high-reliability optoelectronics, power MOSFETs, and precision resistors.

The BPW85 belongs to Vishay's silicon phototransistor family designed for robust, cost-effective visible/NIR detection in industrial controls, safety systems, and consumer remote interfaces-emphasizing consistent angular response and thermal stability.

FAQ

What is the maximum operating temperature for the BPW85?

The BPW85 has an operating temperature range of -40 to +100 °C. Its junction temperature must not exceed 100 °C, and power dissipation must be derated above 55 °C ambient per the thermal curve in Figure 1. At 100 °C ambient, usable power drops to ~15 mW due to R_thJA = 450 K/W. The BPW85 remains functional within this full range when operated within absolute maximum ratings.

Does the BPW85 require an external base connection?

No, the BPW85 is a two-terminal phototransistor with the base terminal internally unconnected and optically coupled. Illumination generates base current directly in the silicon junction, eliminating need for external biasing. This simplifies circuit design and improves noise immunity compared to photodiodes with external amplifiers. The BPW85 functions solely as a collector-emitter current-controlled device activated by light.

How does the BPW85 spectral response compare to common IR LEDs?

The BPW85 has peak sensitivity at 850 nm and responds from 450 to 1080 nm, aligning well with standard 850 nm and 940 nm IR LEDs. Its relative spectral sensitivity curve (Figure 10) shows >80% response at 940 nm, making it suitable for most remote control and data link applications. The BPW85 delivers usable output even with 940 nm emitters, though slightly lower than at 850 nm.

Can the BPW85 be used in analog light measurement applications?

Yes-the BPW85 provides linear collector light current vs. irradiance over ~2 decades (Figure 4), supporting analog light-level sensing. However, its output varies significantly with temperature (Figure 3), so compensation is required for precision measurement. For analog use, the BPW85 should be paired with a matched thermistor or calibrated lookup table. The BPW85's 3 pF capacitance also permits stable op-amp transimpedance configurations up to ~100 kHz.

What is the meaning of "T-1 package" for the BPW85?

The T-1 designation indicates a standardized through-hole package with a 3.175 mm (1/8 inch) diameter lens body-specifically Ø3.0 ± 0.1 mm for the BPW85. It uses radial leads spaced 2.54 mm apart, compatible with standard 0.1″ grid PCB layouts. The T-1 form factor ensures mechanical interchangeability with other photodetectors and emitters in optical assemblies, and the clear plastic lens maximizes transmission across visible and NIR wavelengths.