Diodes Incorporated BSR43QTA

Overview

BSR43QTA from Diodes Incorporated is an 80V NPN medium-power transistor in SOT89 package, rated for 1A continuous collector current and featuring V_CE(sat) < 250 mV at 150 mA. It is AEC-Q101 qualified, RoHS-compliant, and designed for automotive load switching in solenoid, relay, and DC–DC module drivers.

For engineers reviewing the BSR43QTA datasheet, BSR43QTA pinout, BSR43QTA application, or BSR43QTA equivalent, key selection criteria include its 80V V_CEO, 1A I_C, low saturation voltage, thermal resistance of 60°C/W on 50 mm² copper, and automotive qualification status.

Technical Context

This NPN bipolar junction transistor operates with a minimum DC current gain (h_FE) of 30 at 100 µA and up to 300 at 100 mA, supporting robust current amplification across wide temperature ranges (−65°C to +150°C). Its f_T of 100 MHz enables reliable switching in medium-frequency control loops.

The device uses a thermally enhanced SOT89 package with exposed collector pad, delivering R_ΘJL = 13°C/W to lead and R_ΘJA = 60°C/W on 50 mm² copper - critical for sustained 1A operation in space-constrained automotive modules.

Key Specifications

Pinout & Package

SOT89 package with exposed collector pad for thermal management; molded green compound (UL 94V-0), matte tin terminals, 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 ZXTN25050DFHTA and MMBT4401LT1G, BSR43QTA uniquely delivers 1A continuous current, 80V rating, and AEC-Q101 compliance in a thermally optimized SOT89 - making it the only drop-in solution for automotive-grade 24V load switching where reliability and thermal headroom are mandatory.

Availability

BSR43QTA is available at Aetrix Electronics and suitable for automotive body control modules, industrial DC–DC converter enable circuits, and industrial relay interface boards requiring stable component supply and long-term lifecycle support.

Supply support for BSR43QTA 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, specializing in high-reliability components for automotive, industrial, and computing markets.

The BSR43 product line delivers AEC-Q101-qualified medium-power transistors optimized for automotive load management - emphasizing thermal robustness, transient immunity, and long-term parametric stability.

FAQ

What is the maximum continuous collector current for BSR43QTA at 100°C ambient?

At T_A = 100°C with 50 mm² copper, BSR43QTA maintains 1A continuous collector current. Derating begins above 100°C per the datasheet curve: at 125°C ambient, max I_C is ~0.75 A. The 1A rating assumes R_ΘJA = 60°C/W and proper PCB thermal layout.

Is BSR43QTA pin-compatible with BSR33QTA?

Yes - BSR43QTA (NPN) and BSR33QTA (PNP) share identical SOT89 pinout (C-E-B) and mechanical footprint. They are complementary devices intended for push-pull or H-bridge configurations, with matched voltage/current ratings and thermal characteristics.

Does BSR43QTA require a base current limiting resistor in typical MCU-driven applications?

Yes - a series base resistor is required to limit I_B and ensure saturation. For 3.3V MCU GPIO driving 150 mA collector load, a 120 Ω resistor yields ~15 mA I_B, satisfying the I_C/I_B = 10 condition specified in the V_CE(sat) test.

Can BSR43QTA replace MMBT4401 in existing 24V automotive designs?

No - MMBT4401 has only 40V V_CEO, risking failure during 24V system load dump events (up to 60V). BSR43QTA's 80V rating, AEC-Q101 qualification, and SOT89 thermal capability make it a purpose-built upgrade, not a drop-in replacement.