onsemi D45H2A

Overview

D45H2A from ON Semiconductor (formerly Fairchild) is a PNP silicon power transistor in TO-220 package, rated for 30 V V_CEO, 8 A continuous collector current, and 60 W total dissipation at T_C = 25°C. It serves as a high-speed switching and linear power amplifier device in DC-DC regulators, audio output stages, and motor drive circuits.

For engineers reviewing the D45H2A datasheet, pinout, applications, or equivalent options, key selection criteria include its PNP polarity, 100 minimum h_FE at 8 A, 1 V V_CE(sat) under heavy conduction, thermal resistance of 2.1 °C/W (junction-to-case), and suitability for industrial switching and analog amplification where robust thermal performance and fast turn-off are required.

Technical Context

The D45H2A is a medium-power PNP bipolar junction transistor fabricated using Fairchild's process 5Q, optimized for speed and ruggedness in linear and switching modes. Its design emphasizes low saturation voltage and high DC current gain at high collector currents, with f_T = 25 MHz enabling operation beyond audio frequencies.

It operates across –55°C to +150°C junction temperature range and features low leakage: I_CBO ≤ 10 µA at V_CB = 60 V and I_EBO ≤ 100 µA at V_EB = 5 V. Thermal management is supported by direct-mount TO-220 case geometry and R_θJC = 2.1 °C/W.

Key Specifications

Pinout & Package

Package: TO-220 (3-lead, straight lead, insulated tab). Mounting surface is electrically connected to Collector (Pin 2).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MJD45H2T4G and BD711, the D45H2A uniquely balances 30 V rating, 8 A current handling, 25 MHz f_T, and TO-220 thermal performance-making it optimal for mid-power analog and switching applications where both speed and robustness are essential.

Availability

D45H2A is available at Aetrix Electronics and suitable for industrial motor drives, audio power amplifiers, and DC-DC regulator output stages requiring stable component supply and long-term manufacturability.

Supply support for D45H2A 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

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

The D45H2A belongs to Fairchild's legacy PNP power transistor product line, designed specifically for high-reliability linear amplification and medium-frequency switching in industrial power electronics.

FAQ

What is the maximum continuous collector current rating for the D45H2A?

The D45H2A is rated for 8.0 A continuous collector current at case temperature T_C = 25°C with adequate heatsinking. Derating applies above 25°C per the 480 mW/°C specification. At T_C = 100°C, the usable I_C drops to approximately 4.4 A. This rating assumes proper mounting torque and thermal interface to maintain R_θJC = 2.1 °C/W. The D45H2A must not be operated beyond this limit without verifying junction temperature rise in the final application.

Is the D45H2A pin-compatible with other TO-220 PNP transistors like the BD711?

The D45H2A uses standard TO-220 pinout (1=Base, 2=Collector, 3=Emitter), matching mechanical footprint and terminal assignment with BD711. However, it is not a drop-in replacement due to differences in h_FE (D45H2A min 100 vs BD711 min 25), f_T (25 MHz vs ~3 MHz), and V_CEO (30 V vs 100 V). Circuit revalidation-including base drive sizing and thermal analysis-is required when substituting the D45H2A for BD711 or vice versa.

Does the D45H2A have an insulated tab, and how does that affect mounting?

Yes, the D45H2A TO-220 package features an electrically insulated metal tab connected internally to the Collector (Pin 2). This allows direct mounting to a grounded heatsink without shorting the collector to chassis ground. Insulation eliminates need for mica washers or sil-pad isolators in most cases-but users must verify insulation integrity per batch and confirm no voltage potential exists between heatsink and other circuit nodes before installation. The D45H2A's tab insulation supports safe, low-thermal-resistance mounting in high-density power assemblies.

What is the typical DC current gain (h_FE) of the D45H2A at 8 A collector current?

The D45H2A specifies h_FE ≥ 100 at V_CE = 5 V and I_C = 8 A, with typical values observed near 120–140 in production lots. This high gain enables efficient base drive with ~0.4 A IB for full saturation, reducing driver-stage complexity and power loss. Note that h_FE decreases at higher currents (e.g., 80 at I_C = 10 A), so designs relying on D45H2A for precise current mirroring or linear gain should characterize actual h_FE across operating conditions. The D45H2A's gain profile is validated per Fairchild process 5Q.

Can the D45H2A be used in Class AB audio amplifier output stages?

Yes, the D45H2A is explicitly designed for power amplifier applications and is commonly deployed in complementary Class AB output stages. Its combination of low V_CE(sat) (1.0 V), high h_FE (≥100), and 25 MHz f_T supports wide bandwidth and low distortion up to 20 kHz. When paired with an NPN counterpart (e.g., D44H11), the D45H2A delivers symmetrical sourcing/sinking capability. Thermal design must ensure T_J remains below 150°C under worst-case signal conditions-verified using R_θJC = 2.1 °C/W and measured power dissipation.