Diodes Incorporated BSR43TA

Overview

BSR43TA from Diodes Incorporated is an 80V NPN medium-power transistor in SOT89 package, rated for 1A continuous collector current, with V_CE(sat) < 250 mV at 150 mA and qualified to AEC-Q101 for automotive reliability. It serves as a high-voltage load switch in solenoid, relay, and DC–DC module drivers.

For engineers reviewing the BSR43TA datasheet, BSR43TA pinout, BSR43TA application, or BSR43TA equivalent, key selection criteria include V_CEO = 80 V, I_C = 1 A, R_ΘJL = 13 °C/W, thermal performance on 15 mm × 15 mm copper, and AEC-Q101 qualification for under-hood automotive use.

Technical Context

This NPN bipolar junction transistor operates in linear or saturated switching mode with guaranteed BV_CEO ≥ 80 V and h_FE = 30–300 across I_C = 100 µA to 500 mA. Its low R_ΘJL = 13 °C/W enables efficient heat transfer via the exposed collector pad to PCB copper.

Designed for robust load management, it supports pulsed I_C up to 2 A and exhibits f_T = 100 MHz at I_C = 50 mA, V_CE = 10 V - enabling fast switching in DC–DC control stages and actuator drive circuits where voltage headroom and thermal margin are critical.

Key Specifications

Pinout & Package

SOT89 package with exposed collector pad for thermal dissipation; molded green compound, UL 94V-0 rated, 0.052 g weight.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ZTX653 and MMBT4401, BSR43TA delivers higher voltage margin, superior thermal resistance, and automotive-grade reliability - making it the preferred choice for 48 V load switching where long-term stability and transient immunity are non-negotiable.

Availability

BSR43TA is available at Aetrix Electronics and suitable for automotive ECU modules, industrial solenoid controllers, and DC–DC converter designs requiring stable component supply and AEC-Q101-compliant sourcing.

Supply support for BSR43TA 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

Diodes Incorporated is a global manufacturer of discrete semiconductors and analog ICs, headquartered in Plano, Texas, with design and manufacturing operations across Asia and the Americas.

The BSR43TA belongs to Diodes' AEC-Q101-qualified bipolar transistor product line, engineered specifically for automotive and industrial load switching applications demanding high voltage, thermal resilience, and long-term reliability.

FAQ

What is the maximum allowable PCB copper area for thermal derating of BSR43TA?

The datasheet specifies three thermal test conditions: 15 mm × 15 mm (1 oz), 25 mm × 25 mm (1 oz), and 50 mm × 50 mm (1 oz) copper areas. At 50 mm × 50 mm, R_ΘJA improves to 60 °C/W, enabling 2.1 W power dissipation at T_A = 25 °C. Larger copper beyond 50 mm × 50 mm yields diminishing returns per the published derating curves.

Can BSR43TA replace BSR33 in complementary pair configurations?

Yes - BSR43TA is explicitly designated as the NPN complement to the PNP BSR33. Both share identical SOT89 packaging, voltage ratings (80 V), and thermal characteristics. Pinout alignment (C-E-B vs C-E-B) and matched h_FE ranges allow direct pairing in push-pull or H-bridge driver stages without layout modification.

Does BSR43TA require a base resistor when driven by a 3.3 V MCU GPIO?

Yes - a series base resistor is mandatory. With V_BE(sat) ≈ 1.0 V at I_C = 150 mA, a 3.3 V GPIO requires ~150–220 Ω to deliver 15 mA base current (I_C/I_B = 10). Omitting this resistor risks excessive base current, thermal runaway, and premature failure.

Is the exposed collector pad electrically isolated from other pins?

No - the exposed collector pad is internally connected to the collector terminal. It must be routed to the same net as the collector pin (Pin 1) and tied to a low-impedance, thermally optimized copper pour. Using it as a heatsink while floating it electrically will cause short-circuit failure.