onsemi BD37810STU

Overview

BD37810STU from Fairchild Semiconductor is a PNP epitaxial silicon transistor rated for -60 V V_CEO, -75 V V_CBO, -2 A continuous collector current, 25 W collector dissipation at T_C = 25°C, and 150°C maximum junction temperature-designed for medium-power linear amplification and switching in industrial power supplies and motor control circuits.

For engineers reviewing the BD37810STU datasheet, pinout, applications, or equivalent options, key selection criteria include its TO-126 package, h_FE range of 63–160 at I_C = -0.15 A, V_CE(sat) ≤ -1 V at I_C = -1 A / I_B = -0.1 A, and safe operating area validated up to -30 V / -0.5 A with t_OFF = 500 ns.

Technical Context

This PNP bipolar junction transistor operates in active, saturation, and cutoff regions with defined DC current gain (h_FE1 = 63–160 at V_CE = -2 V, I_C = -0.15 A; h_FE2 = 20–100 at V_CE = -2 V, I_C = -1 A), low saturation voltage (V_CE(sat) ≤ -1 V), and fast switching performance (t_ON = 50 ns, t_OFF = 500 ns under specified test conditions).

Its breakdown characteristics include V_CBO = -75 V and V_CEO(sus) = -60 V at I_C = -100 mA with base open, supporting robust operation in inductive load switching and linear regulator pass elements where reverse-biased junction integrity and secondary breakdown immunity are critical.

Key Specifications

Pinout & Package

BD37810STU is housed in a TO-126 plastic package with three leads: Emitter (Pin 1), Collector (Pin 2), Base (Pin 3). The package features a metal tab connected to the collector for thermal and electrical connection to heatsinks.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MJD2955G and BD377, BD37810STU offers optimized thermal-mechanical fit in space-constrained TO-126 layouts and guaranteed h_FE banding for consistent bias design, whereas MJD2955G suits higher-power needs and BD377 serves strictly as a complementary partner-not a functional alternative.

Availability

BD37810STU is available at Aetrix Electronics and suitable for industrial power supply regulation, DC motor direction control, and audio amplifier output stages requiring stable component supply, long-term obsolescence management, and traceable sourcing.

Supply support for BD37810STU 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

Fairchild Semiconductor was a U.S.-based semiconductor company specializing in analog and discrete power devices, acquired by ON Semiconductor in 2016; its legacy products remain widely deployed in industrial and automotive systems.

BD37810STU belongs to the BD376/378/380 family of medium-power PNP transistors designed specifically for linear amplification and switching in cost-sensitive, thermally constrained applications such as power supply pass elements and motor control half-bridges.

FAQ

What is the maximum continuous collector current rating for BD37810STU?

The BD37810STU has a maximum continuous collector current (I_C) rating of -2 A at T_C = 25°C. This rating decreases with rising case temperature per the published power derating curve (Figure 5), reaching approximately -1.2 A at T_C = 100°C. Exceeding this limit risks thermal runaway or permanent junction damage. The BD37810STU must be mounted on an appropriately sized heatsink to maintain safe operating temperatures under sustained load.

Is BD37810STU pin-compatible with BD377?

No, BD37810STU is not pin-compatible with BD377. While both use the TO-126 package and share identical physical pin locations (Emitter–Collector–Base), BD377 is an NPN transistor with reversed polarity: its emitter is Pin 1, collector Pin 2, and base Pin 3-same mechanical layout but opposite semiconductor type. Interchanging them without circuit redesign will result in non-functional or destructive operation. The BD37810STU and BD377 are complementary devices intended for paired use-not drop-in replacements.

What is the guaranteed h_FE range for BD37810STU at I_C = -0.15 A?

The BD37810STU is classified in the "10" h_FE band, guaranteeing a DC current gain (h_FE1) of 63–160 when tested at V_CE = -2 V and I_C = -0.15 A. This range is verified per production lot and ensures predictable bias point stability in amplifier and linear regulator designs without requiring post-manufacture sorting. The BD37810STU's h_FE2 (at I_C = -1 A) is 20–100, reflecting typical beta droop at higher currents.

Can BD37810STU be used in switching applications above 50 kHz?

Yes, BD37810STU supports switching operation up to approximately 100 kHz in well-designed circuits. Its t_ON = 50 ns and t_OFF = 500 ns (measured under V_CC = -30 V, I_C = -0.5 A, R_L = 60 Ω) yield a practical maximum duty-cycle-limited frequency near 100 kHz. However, switching efficiency degrades above this due to increased switching losses and SOA constraints. For reliable BD37810STU operation at 50–100 kHz, use strong base drive (I_B ≥ -0.1 A) and minimize stray inductance in collector/emitter paths.

What is the safe operating area (SOA) limit for BD37810STU at T_C = 25°C?

At T_C = 25°C, the BD37810STU's safe operating area (SOA) is bounded by four limits: DC (25 W / -2 A), single-pulse (up to -30 V / -0.5 A for 10 ms), secondary breakdown (curved boundary in Figure 4), and V_CEO (-60 V). The SOA graph (Figure 4) shows that simultaneous high voltage and high current cannot be sustained-e.g., at V_CE = -20 V, maximum I_C is ~ -1.2 A. Derating is mandatory above 25°C; the BD37810STU must never operate outside the published SOA envelope to prevent thermal runaway or bond-wire failure.