STMicroelectronics D45H8

Overview

D45H8 from STMicroelectronics is a PNP silicon power bipolar junction transistor (BJT) designed for linear amplification and switching in high-current, medium-voltage circuits. It features 60 V V_CEO, 10 A continuous collector current, 50 W total dissipation at T_case = 25 °C, and low 1 V V_CE(sat) at I_C = 8 A / I_B = 0.4 A - enabling efficient operation in audio power amplifier output stages.

For engineers reviewing the D45H8 datasheet, D45H8 pinout, D45H8 application, or D45H8 equivalent, key selection criteria include its PNP polarity, TO-220 package thermal performance (R_thJC = 2.5 °C/W), DC current gain (h_FE ≥ 60 at I_C = 2 A), safe operating area limits, and complementary pairing with D44H8 in push-pull configurations.

Technical Context

The D45H8 operates as a medium-power PNP BJT using multi-epitaxial planar technology, optimized for stable DC current gain across I_C = 2–4 A and V_CE = 1 V. Its negative-polarity absolute ratings (e.g., –60 V V_CEO, –10 A I_C) reflect PNP conduction behavior and require reversed biasing versus NPN counterparts.

Thermal design relies on direct case-to-heatsink mounting via the insulated tab (TO-220 Type A), with junction-to-case resistance capped at 2.5 °C/W. The device supports pulse operation up to 20 A I_CM, but sustained linear use is constrained by derating above 25 °C case temperature per Figure 3.

Key Specifications

Pinout & Package

Supplied in TO-220 Type A package with insulated metal tab (pin 1 = Emitter, pin 2 = Base, pin 3 = Collector). Mounting requires electrically isolated heatsink interface due to tab connection to collector.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MJD45H8T4 and BD711, the D45H8 delivers optimal balance of voltage rating, current capacity, and gain linearity in through-hole TO-220 form - making it preferred for thermally demanding, medium-voltage linear and switching roles where mechanical robustness and heatsink compatibility are critical.

Availability

D45H8 is available at Aetrix Electronics and suitable for audio power amplifiers, DC motor drivers, linear voltage regulators, and low-frequency SMPS requiring stable component supply with consistent parametric performance across production lots.

Supply support for D45H8 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, designing and manufacturing analog, microcontroller, power, and sensor solutions for industrial, automotive, and consumer markets.

The D45H8 belongs to ST's legacy power bipolar transistor family, engineered specifically for cost-sensitive, high-reliability linear and switching applications where ruggedness, thermal stability, and complementary pairing are essential.

FAQ

Is the D45H8 RoHS-compliant and lead-free?

Yes, the D45H8 is manufactured in ST's ECOPACK®-compliant TO-220 package, meeting RoHS Directive 2011/65/EU and featuring lead-free terminations. The device carries the "ECOPACK2" designation per ST's environmental compliance documentation, with no exemptions applied.

Can D45H8 be used in parallel with another D45H8 for higher current?

Parallel operation is not recommended without individual emitter resistors (≥ 0.1 Ω) and matched h_FE/V_BE(sat) devices. The D45H8 lacks built-in current-sharing features; mismatched thermal coupling or gain causes current hogging and premature failure. Use a single higher-rated device instead.

What is the maximum safe operating area (SOA) limit at 100 °C case temperature?

At T_case = 100 °C, the SOA is derated to ~3.5 A at 40 V (DC) per Figure 2 and Figure 3. Pulse operation (≤ 300 µs, ≤2% duty) extends limits to ~8 A at 60 V. Exceeding these boundaries risks second breakdown or thermal runaway.

Does D45H8 require a base resistor when driven by a microcontroller GPIO?

Yes - a series base resistor is mandatory. With V_BE(sat) ≈ –1.5 V and required I_B = –0.4 A for full saturation, a 3.3 V GPIO would need ~12 Ω (accounting for voltage drop). However, microcontrollers cannot source/sink 0.4 A; a driver stage (e.g., small-signal BJT or logic-level MOSFET) is required.