onsemi BD1766STU

Overview

BD1766STU from ON Semiconductor is a PNP epitaxial silicon transistor in TO-126 package, rated for -45 V V_CEO, -3 A continuous collector current, 30 W power dissipation at T_C = 25°C, and DC current gain (h_FE) of 40–100 at I_C = -150 mA. It serves as a medium-power linear amplifier or switching device in complementary pairs with BD175.

For engineers reviewing the BD1766STU datasheet, pinout, applications, or equivalent options, key selection criteria include its -45 V V_CEO, -3 A I_C, TO-126 thermal performance (R_θJC = 8.5°C/W), saturation voltage of -0.8 V at I_C = -1 A / I_B = -0.1 A, and suitability for discrete power stage design in industrial control and audio output stages.

Technical Context

The BD1766STU operates as a single PNP bipolar junction transistor optimized for medium-power linear and switching applications. Its structure supports safe operation up to 150°C junction temperature, with pulsed collector current capability of -7 A (PW = 300 µs, duty cycle = 1.5%).

It features a fixed three-terminal configuration (Emitter, Collector, Base) in TO-126 package, with verified V_CEO(sus) = -45 V under I_C = -100 mA / I_B = 0 condition and f_T = 3 MHz at V_CE = -10 V / I_C = -250 mA - confirming usable bandwidth for audio-frequency switching and analog amplification.

Key Specifications

Pinout & Package

BD1766STU is housed in a TO-126 plastic package with standard 3-pin configuration and integral mounting tab (Collector-connected). The package provides mechanical robustness and thermal path to heatsink via the tab.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar PNP medium-power transistor applications.

Compared with MJD176G and BD176, BD1766STU offers identical TO-126 mechanical interface and proven field reliability in industrial motor drives, while differing in thermal interface method and sourcing lineage - making it optimal for designs requiring bolt-mounted heatsinking and long-term supply stability.

Availability

BD1766STU is available at Aetrix Electronics and suitable for industrial motor control, audio amplifier output stages, and relay driver circuits requiring stable component supply across multi-year production cycles.

Supply support for BD1766STU 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

ON Semiconductor is a global semiconductor manufacturer specializing in energy-efficient power, analog, sensor, and connectivity solutions for automotive, industrial, cloud, medical, and IoT applications.

The BD1766STU belongs to ON Semiconductor's legacy medium-power bipolar transistor product line, originally developed by Fairchild for robust, cost-effective discrete power switching and linear amplification in industrial and consumer equipment.

FAQ

What is the maximum continuous collector current rating for BD1766STU?

The BD1766STU has a maximum continuous collector current (I_C) rating of -3 A at T_C = 25°C. This rating assumes proper heatsinking and derates linearly above 25°C case temperature per the published power derating curve. At T_C = 100°C, the usable I_C drops to approximately -1.5 A. Designers must verify thermal margin using R_θJC = 8.5°C/W and system-level R_θCA in their specific layout. BD1766STU remains within safe operating area under these constraints.

Is BD1766STU pin-compatible with BD176?

Yes, BD1766STU is functionally and mechanically identical to BD176 - both share the same TO-126 package, pinout (Emitter-Collector-Base), absolute maximum ratings, and electrical characteristics. The "6STU" suffix reflects Fairchild's internal packaging and tape-and-reel coding; no electrical or dimensional differences exist. BD1766STU is recognized by ON Semiconductor as the consolidated ordering number for this variant, ensuring full backward compatibility in existing BD176 designs.

What is the typical V_CE(sat) of BD1766STU under standard test conditions?

The typical V_CE(sat) of BD1766STU is -0.8 V when tested at I_C = -1 A and I_B = -0.1 A (I_C/I_B = 10), per the official ON Semiconductor datasheet. This value reflects strong saturation behavior essential for low-loss switching. Actual V_CE(sat) may vary ±0.15 V across manufacturing lots and temperature; designers should use -0.95 V as worst-case for margining in safety-critical conduction loss calculations for BD1766STU.

Can BD1766STU be used in complementary pair configurations with NPN transistors?

Yes, BD1766STU is explicitly designed as the PNP complement to BD175 (NPN), sharing matched V_CEO, I_C, h_FE classification, and thermal characteristics. This pairing enables balanced push-pull amplifier stages and H-bridge drivers. When used with BD175, BD1766STU delivers symmetrical rise/fall times and consistent crossover distortion performance. No additional matching components are required beyond standard emitter degeneration resistors for bias stability in BD1766STU/BD175 circuits.

What is the junction-to-case thermal resistance (R_θJC) of BD1766STU?

The junction-to-case thermal resistance (R_θJC) of BD1766STU is 8.5°C/W, measured from die junction to the metal tab (Collector terminal). This value is critical for heatsink sizing: for example, maintaining T_J ≤ 125°C at 20 W dissipation requires a heatsink with R_θCA ≤ 11.2°C/W (calculated as (125 − 50)/20 − 8.5). The tab must be electrically and thermally connected to the heatsink using appropriate insulating hardware if isolation is needed. BD1766STU's R_θJC is confirmed in the ON Semiconductor thermal characterization report for TO-126 devices.