onsemi BD787

Overview

BD787G from onsemi is an NPN complementary silicon power transistor in TO-225 package, rated for 60 V_CEO, 4 A continuous collector current, and 15 W power dissipation at T_C = 25°C. It delivers f_T = 50 MHz bandwidth and low V_CE(sat) (0.4 V at I_C = 500 mA, I_B = 50 mA), enabling use in low-current high-speed switching and lower-power audio amplifier stages.

For engineers reviewing the BD787G datasheet, pinout, applications, or equivalent options, this page provides verified electrical parameters, thermal derating behavior, safe operating area limits, junction-to-case thermal resistance (8.34°C/W), and validated complementary PNP pairing with BD788G - all critical for discrete power stage design and thermal layout validation.

Technical Context

The BD787G operates as a medium-power NPN bipolar junction transistor optimized for linear and switching operation up to 50 MHz. Its DC current gain (h_FE) ranges from 40–250 across 200 mA–4 A collector currents at V_CE = 3 V, and its Cob = 50 pF at V_CB = 10 V supports stable high-frequency gain control.

Thermal performance is defined by R_JC = 8.34°C/W and a maximum junction temperature of +150°C. The device's active-region safe operating area (SOA) is bounded by bonding wire limits, second breakdown, and thermal constraints - with pulse SOA curves provided for durations from 100 µs to DC at T_C = 25°C.

Key Specifications

Pinout & Package

BD787G uses the TO-225 package (Case 77-09, Style 1), a 4-pin plastic power package with pins 2 and 4 internally connected to the collector, pin 1 as emitter, and pin 3 as base. The metal tab (backside) is electrically connected to the collector and serves as both thermal path and mounting surface.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MJD127G and BD139, BD787G offers superior bandwidth (50 MHz vs. 3 MHz/unknown), lower saturation voltage (0.4 V vs. 1.5 V/1.2 V), and validated complementary pairing with BD788G - making it uniquely suited for balanced, medium-power, high-fidelity analog and switching stages where gain-bandwidth and thermal efficiency are prioritized.

Availability

BD787G is available at Aetrix Electronics and suitable for audio amplifier driver stages, DC motor speed control circuits, and linear regulator pass elements requiring stable component supply, RoHS compliance, and proven thermal reliability in TO-225 packages.

Supply support for BD787G 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

onsemi (formerly ON Semiconductor) is a global semiconductor supplier specializing in power management, analog, sensor, and discrete solutions for automotive, industrial, and consumer markets.

The BD787G belongs to onsemi's complementary silicon power transistor family, designed specifically for cost-effective, thermally robust, and electrically balanced NPN/PNP pairs in audio, power control, and switching applications.

FAQ

What is the maximum junction temperature for BD787G?

The BD787G has a maximum operating and storage junction temperature range of –65°C to +150°C. This specification ensures reliable operation in industrial environments and under transient thermal stress, provided the thermal design maintains T_J ≤ 150°C using the stated R_JC = 8.34°C/W and appropriate heatsinking. Exceeding this limit risks permanent degradation of h_FE and increased leakage.

Is BD787G pin-compatible with BD788G?

No - BD787G (NPN) and BD788G (PNP) share identical TO-225 package pinout (Style 1: Emitter–Collector–Base–Collector), but they are complementary devices, not pin-compatible replacements. Their circuit roles differ fundamentally: BD787G sinks current from collector to emitter, while BD788G sources current from emitter to collector. They are intended for paired use in push-pull or complementary amplifier topologies, not substitution.

Does BD787G require a heatsink in typical operation?

Yes - BD787G dissipates up to 15 W at T_C = 25°C, and its R_JC = 8.34°C/W means even modest power levels (e.g., 5 W) raise junction temperature significantly above ambient without thermal management. A heatsink is mandatory for continuous operation above ~1 W; thermal design must account for R_CA (case-to-ambient) to keep T_J ≤ 150°C under worst-case ambient and load conditions.

What is the safe operating area (SOA) limitation for BD787G at DC operation?

At DC (single-pulse, 100% duty cycle), the BD787G's SOA is thermally limited to approximately 2 A at 30 V_CE or 1 A at 60 V_CE when T_C = 25°C - derived from its 15 W power rating and Figure 5 curves. Second breakdown does not dominate at DC; instead, average junction temperature governs the limit. Derating is required above 25°C case temperature at 0.12 W/°C.

Can BD787G be used in Class-D amplifier output stages?

No - BD787G is a bipolar junction transistor optimized for linear and medium-speed switching (≤50 MHz f_T), not high-efficiency, high-frequency Class-D operation. Its relatively high V_CE(sat), lack of integrated gate drive, and slower switching times (t_on/t_off in hundreds of ns) make it unsuitable for >200 kHz switching frequencies typical of modern Class-D ICs or MOSFET-based half-bridges. Use dedicated Class-D controller + MOSFETs instead.