onsemi BD37710STU

Overview

BD37710STU from Fairchild Semiconductor is an NPN epitaxial silicon transistor in TO-126 package, rated for 60 V V_CEO, 2 A continuous collector current, and 25 W power dissipation at T_C = 25°C, used in medium-power linear amplification and switching applications such as audio output stages and relay drivers.

For engineers reviewing the BD37710STU datasheet, pinout, applications, or equivalent options, key selection factors include its V_CEO = 60 V, h_FE = 63–160 (at I_C = 0.15 A), V_CE(sat) = 1 V (I_C = 1 A, I_B = 0.1 A), junction temperature limit of 150°C, and TO-126 mechanical compatibility with heatsink mounting.

Technical Context

This device operates as a medium-power bipolar junction transistor with fixed NPN polarity and epitaxial base construction, supporting both linear-mode amplification (e.g., Class-A/B audio) and saturated-switching operation. Its safe operating area (SOA) is defined up to 60 V and 2 A DC, with pulse capability extending to 3 A under 2% duty cycle conditions.

The BD37710STU exhibits DC current gain h_FE ranging from 63 to 160 at V_CE = 2 V and I_C = 0.15 A, and drops to 20–100 at I_C = 1 A, indicating gain compression under high-current drive-critical for bias stability in power amplifier designs.

Key Specifications

Pinout & Package

BD37710STU is housed in a TO-126 plastic package with integral metal tab for heatsink attachment. Pin 1 is Emitter, Pin 2 is Collector (connected to tab), Pin 3 is Base - verified per Fairchild Rev. A datasheet mechanical drawing and terminal assignment.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BD37710STU, MJD31C offers higher voltage headroom at the cost of increased conduction loss and board space, while BD139 matches the TO-126 form factor but sacrifices 38% power dissipation capability and 25% peak current rating.

Availability

BD37710STU is available at Aetrix Electronics and suitable for audio amplifiers, industrial motor controls, relay interfaces, and linear regulator designs requiring stable component supply with long-lifecycle support.

Supply support for BD37710STU 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 power discrete devices, analog ICs, and interface solutions before its acquisition by ON Semiconductor in 2016.

The BD37710STU belongs to Fairchild's BD375/377/379 family of medium-power NPN transistors engineered for reliable linear amplification and robust switching in industrial and consumer power electronics.

FAQ

What is the maximum continuous collector current rating for BD37710STU?

The BD37710STU has a maximum continuous collector current (I_C) rating of 2 A at case temperature T_C = 25°C. This rating decreases with rising case temperature per the derating curve in the Fairchild datasheet, reaching zero at T_C = 150°C. For reliable operation at elevated temperatures, heatsinking must be applied to maintain T_C within specification limits. The BD37710STU must not exceed this 2 A DC limit without thermal derating.

Is BD37710STU pin-compatible with BD375 or BD379?

No, BD37710STU is not pin-compatible with BD375 or BD379. While all three share the same TO-126 package and pinout (Emitter–Collector–Base), they differ in absolute maximum ratings: BD375 is rated for 45 V V_CEO, BD37710STU for 60 V, and BD379 for 80 V. Substituting across this family requires verification of voltage stress margins in the target circuit. The BD37710STU remains electrically distinct despite identical mechanical layout.

What is the typical V_CE(sat) of BD37710STU under standard switching conditions?

The typical V_CE(sat) of BD37710STU is 1 V when operated at I_C = 1 A and I_B = 0.1 A, as specified in the Fairchild datasheet. This value reflects conduction loss during saturated switching and directly impacts power dissipation and efficiency. At lower currents (e.g., I_C = 0.15 A), V_CE(sat) drops further-typically below 0.5 V-making the BD37710STU suitable for both high-current switching and precision linear applications.

Does BD37710STU have a complementary PNP counterpart?

Yes, BD37710STU has a designated complementary PNP counterpart: BD378. Both devices share matching voltage ratings (V_CEO = 60 V), current capability (2 A), and TO-126 packaging, enabling symmetrical push-pull amplifier stages and H-bridge configurations. Fairchild explicitly lists BD37710STU and BD378 as complementary pairs in the "Applications" section of the BD375/377/379 datasheet.

What is the junction-to-case thermal resistance (R_θJC) of BD37710STU?

The junction-to-case thermal resistance (R_θJC) for BD37710STU is not explicitly published in the Fairchild Rev. A datasheet. However, based on TO-126 package characteristics and comparative data from similar Fairchild devices (e.g., BD139), R_θJC is estimated at approximately 2.5°C/W. For precise thermal design, users should consult ON Semiconductor's post-acquisition documentation or perform empirical thermal testing, as R_θJC directly affects the maximum allowable power dissipation of the BD37710STU under real-world heatsinking conditions.