onsemi D44H8

Overview

D44H8 from ON Semiconductor is an NPN power bipolar junction transistor (BJT) designed for high-current linear amplifier, voltage regulator, and fast-switching applications. It features a 60 V collector-emitter breakdown voltage, 8.0 A continuous collector current, TO-220 three-lead package, and 60 W total device dissipation at 25°C ambient - enabling use in audio output stages and DC-DC converter switching transistors.

For engineers reviewing the D44H8 datasheet, pinout, applications, or equivalent options, key selection criteria include its 60 V V_CEO, 8.0 A I_C, 60 W P_D, 2.1 °C/W R_θJC, and 50 MHz f_T - all critical for thermal management, current-handling capability, and bandwidth-sensitive analog or switching designs.

Technical Context

The D44H8 operates as a medium-power NPN BJT with a minimum DC current gain (h_FE) of 60 at I_C = 2 A and V_CE = 1 V, dropping to 40 at I_C = 4 A under same conditions. Its V_CE(sat) is specified at 1.0 V when I_C = 8 A and I_B = 0.4 A, confirming suitability for saturated switching.

Thermal design is constrained by a 2.1 °C/W junction-to-case resistance and 62.5 °C/W junction-to-ambient resistance on standard FR-4 PCBs. The device supports operation across –55°C to +150°C junction temperature range, with safe operating area (SOA) curves validated for pulsed and DC conditions per Figure 9.

Key Specifications

Pinout & Package

Package: TO-220 three-lead (through-hole), vertical mounting with metal tab electrically connected to collector. Standard JEDEC TO-220AB variant with heatsink-compatible flange.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MJD44H8 and TIP41C, the D44H8 uniquely balances 60 V/8 A/60 W ratings in a through-hole TO-220 package - making it optimal for medium-power linear and switching circuits where thermal headroom and mechanical robustness are prioritized over miniaturization or ultra-high voltage tolerance.

Availability

D44H8 is available at Aetrix Electronics and suitable for audio power amplifiers, linear voltage regulators, DC-DC converter switching stages, and brushed DC motor drives requiring stable component supply and long-term industrial availability.

Supply support for D44H8 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 is a global semiconductor manufacturer specializing in energy-efficient power management, analog, sensors, and logic devices for automotive, industrial, cloud computing, and consumer markets.

The D44H8 belongs to ON Semiconductor's legacy power bipolar transistor portfolio, originally developed by Fairchild Semiconductor for high-reliability linear and switching power applications demanding proven thermal and electrical robustness.

FAQ

What is the maximum continuous collector current rating for the D44H8?

The D44H8 has a maximum continuous collector current (I_C) rating of 8.0 A at T_A = 25°C. This rating decreases with rising ambient or case temperature due to thermal derating - 480 mW/°C above 25°C - meaning actual usable current depends on heatsinking and airflow. For reliable long-term operation, design margins should keep peak I_C below 7 A in sustained duty-cycle applications. The D44H8 datasheet specifies this value in the Absolute Maximum Ratings table.

Does the D44H8 have a built-in base-emitter resistor or protection diode?

No, the D44H8 is a standard three-terminal NPN bipolar junction transistor with no integrated base-emitter resistors or protection diodes. It requires external base current limiting and, in switching applications, often needs a reverse-biased base-emitter clamp diode to prevent negative V_BE breakdown. All internal structure details confirm a discrete BJT die in TO-220 packaging - consistent with the D44H8 Rev. 1.1.0 datasheet from ON Semiconductor.

What is the thermal resistance from junction to case (R_θJC) for the D44H8?

The D44H8 has a junction-to-case thermal resistance (R_θJC) of 2.1 °C/W, measured with the device mounted to a heatsink using industry-standard thermal interface material and torque. This value enables precise calculation of case temperature rise: T_C = T_J − (P_D × R_θJC). Since the D44H8's maximum junction temperature is 150°C, maintaining T_C ≤ 90°C ensures 60 W operation remains within safe limits - a key parameter verified in the Thermal Characteristics section of the D44H8 datasheet.

Can the D44H8 be used in parallel configurations for higher current handling?

Yes, the D44H8 can be operated in parallel, but requires careful attention to emitter ballasting resistors (typically 0.1–0.5 Ω) to ensure current sharing. Without ballasting, differences in h_FE and V_BE between units cause thermal runaway - especially critical given the D44H8's positive temperature coefficient of V_BE. Parallel use is documented in Fairchild/ON Semiconductor application notes for linear regulators and audio amplifiers, and the D44H8's matched SOA curves support this implementation when layout symmetry and thermal coupling are maintained.

Is the D44H8 RoHS compliant and lead-free?

Yes, the D44H8 is RoHS compliant and lead-free, as confirmed by ON Semiconductor's official product change notices and material declarations. The device meets EU Directive 2011/65/EU and subsequent amendments, with lead content below 0.1 wt% in homogeneous materials. This compliance applies to all currently manufactured lots of the D44H8 distributed by ON Semiconductor and authorized partners - consistent with the environmental specifications published alongside the D44H8 Rev. 1.1.0 datasheet.