Vishay Semiconductor Opto Division BPW85C

Overview

BPW85C from Vishay Semiconductors is a silicon NPN phototransistor in a T-1 (Ø3 mm) clear plastic package, optimized for visible and near-infrared detection with 3–8 mA collector light current at 1 mW/cm² irradiance (λ = 950 nm, V_CE = 5 V). It delivers fast switching (t_on = 2.0 µs, t_off = 2.3 µs), ±25° half-sensitivity angle, and operates across –40 °C to +100 °C ambient.

For engineers reviewing the BPW85C datasheet, BPW85C pinout, BPW85C application, or BPW85C equivalent, this page provides verified specifications, package geometry, spectral response data, timing behavior under load, and direct alternatives for optical sensing designs requiring high radiant sensitivity and stable IR detection performance.

Technical Context

The BPW85C functions as a light-controlled NPN transistor where incident radiation generates base current, enabling proportional collector current flow without external biasing. Its spectral response spans 450–1080 nm with peak sensitivity at 850 nm, and it exhibits low dark current (≤200 nA at V_CE = 20 V).

Thermal resistance is 450 K/W (junction-to-ambient, with Ø0.14 mm² Cu wire), limiting power dissipation to 100 mW at ≤55 °C ambient. Absolute maximum ratings include V_CEO = 70 V, I_C = 50 mA, and T_j = 100 °C - defining safe operating boundaries for pulsed and DC optical switch applications.

Key Specifications

Pinout & Package

BPW85C uses a 2-pin T-1 (Ø3 mm) radial-leaded plastic package with standard anode/cathode orientation for phototransistors: lead 1 = emitter, lead 2 = collector. The package has no base connection; operation relies solely on photogenerated base current.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TEPT5600 and QSE113, the BPW85C offers balanced radiant sensitivity (3–8 mA), industry-standard ±25° viewing angle, and proven thermal stability up to 100 °C - making it optimal for general-purpose industrial and consumer IR detection where robustness and compatibility with legacy 950 nm sources are prioritized.

Availability

BPW85C is available at Aetrix Electronics and suitable for optical encoder position sensing, IR proximity detection, industrial safety light curtains, and smoke detector optical chambers requiring stable component supply and consistent radiant sensitivity across production batches.

Supply support for BPW85C 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 semiconductor manufacturer specializing in discrete components, sensors, and passive devices, with emphasis on reliability, precision, and long-term industrial support.

The BPW85C belongs to Vishay's silicon phototransistor family designed for high-sensitivity, wide-spectrum optoelectronic detection in industrial automation, safety systems, and consumer appliances - emphasizing stable performance across temperature and irradiance variations.

FAQ

What is the maximum collector current rating for BPW85C?

The BPW85C has an absolute maximum continuous collector current (I_C) of 50 mA and a peak collector current (I_CM) of 100 mA under pulsed conditions (duty cycle ≤ 0.5, pulse width ≤ 10 ms). These limits ensure safe operation without junction overheating or degradation. Always verify actual operating current against the derated power curve in Figure 1 of the Vishay datasheet 81531, especially above 55 °C ambient.

Does BPW85C require an external base connection?

No, the BPW85C is a two-terminal phototransistor with no base lead. It operates exclusively via photogenerated base current - emitter and collector are the only accessible terminals. This simplifies PCB layout and eliminates bias network design, but also means gain and response cannot be externally adjusted. The device is intended for use in common-emitter or common-collector configurations with appropriate load resistors.

What is the spectral peak sensitivity wavelength of BPW85C?

The BPW85C has a peak spectral sensitivity (λ_p) at 850 nm, with usable response spanning 450–1080 nm. This makes it highly responsive to standard 850 nm and 950 nm infrared LEDs, while also detecting visible red light (620–750 nm) and near-IR up to 1080 nm. The relative spectral sensitivity curve (Figure 10) confirms strongest response within ±50 nm of 850 nm.

Can BPW85C be used in high-temperature environments like automotive under-hood applications?

The BPW85C is rated for operation from –40 °C to +100 °C ambient temperature, and its junction temperature must not exceed 100 °C. While this supports many under-dash or cabin-mounted automotive applications, under-hood use requires careful thermal analysis - including PCB copper area, airflow, and nearby heat sources - due to its 450 K/W junction-to-ambient thermal resistance. Derating per Figure 1 is mandatory above 55 °C ambient.

How does BPW85C differ from BPW85B in terms of light current output?

The BPW85C delivers a minimum collector light current (I_ca) of 3.0 mA under standardized test conditions (E_e = 1 mW/cm², λ = 950 nm, V_CE = 5 V), whereas BPW85B specifies 1.5 mA minimum. Both share identical package, angular response (±25°), spectral range (450–1080 nm), and timing characteristics. The BPW85C is selected when higher output current is needed for improved noise margin or reduced gain requirements in downstream circuitry.