onsemi NZT45H8

Overview

NZT45H8 from ON Semiconductor is a PNP silicon power transistor designed for high-current linear amplification and switching in regulator and audio amplifier circuits. It delivers −8 A continuous collector current, −60 V collector-emitter breakdown voltage, and 1.5 W total device dissipation in SOT-223 package, operating across −55 °C to +150 °C junction temperature range.

For engineers reviewing the NZT45H8 datasheet, pinout, applications, or equivalent options, key selection considerations include its PNP polarity, SOT-223 thermal performance (R_θJA = 83.3 °C/W), DC current gain (h_FE = 40–60 at −2 to −4 A), saturation voltages (V_CE(sat) = −1.0 V at −8 A), and 40 MHz f_T bandwidth.

Technical Context

The NZT45H8 is a discrete bipolar junction transistor optimized for medium-power analog and switching applications where speed and thermal stability are critical. Its design supports fast turn-on/turn-off via low base-emitter on voltage (−0.54 to −0.65 V) and controlled saturation behavior (V_BE(sat) = −1.5 V at −8 A).

It operates as a single-ended PNP switch or Class AB output stage element, with validated safe operating area up to −8 A and −60 V under pulsed conditions. The SOT-223 package enables surface-mount integration while maintaining sufficient thermal margin for regulated power supply and audio driver use cases.

Key Specifications

Pinout & Package

The NZT45H8 is housed in a SOT-223 4-lead molded plastic package with exposed emitter pad for enhanced thermal conduction. Pin 1 is Base, Pin 2 is Collector, Pin 3 is Emitter, and Pin 4 is Emitter (tied internally to Pin 3). The package supports surface-mount assembly and requires minimum land pattern per JEDEC MS-012.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MJD45H11T4 and ZTX951, the NZT45H8 uniquely balances −8 A current capability, −60 V rating, 40 MHz bandwidth, and SOT-223 thermal performance-making it optimal for mid-power audio, regulator, and motor control where both speed and robustness are required.

Availability

NZT45H8 is available at Aetrix Electronics and suitable for audio amplifier output stages, linear voltage regulator pass elements, and DC motor driver half-bridges requiring stable component supply, consistent parametric performance, and long-term industrial availability.

Supply support for NZT45H8 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 leader in intelligent power and sensing solutions, serving automotive, industrial, cloud computing, and consumer markets with energy-efficient semiconductor technologies.

The NZT45H8 belongs to ON Semiconductor's legacy discrete bipolar transistor portfolio, engineered for reliability in linear amplification, power regulation, and switching applications demanding proven thermal and electrical performance.

FAQ

What is the maximum continuous collector current rating for the NZT45H8?

The NZT45H8 has a maximum continuous collector current (I_C) rating of −8 A at T_A = 25 °C. This rating assumes proper PCB thermal management per JEDEC MS-012 land pattern guidelines. Derating is required above 25 °C at 12 mW/°C, and actual usable current depends on ambient temperature, copper area, and airflow. The NZT45H8 must be operated within its safe operating area (SOA) limits defined in the datasheet to avoid thermal runaway or secondary breakdown.

Does the NZT45H8 have a built-in diode or protection features?

No, the NZT45H8 is a bare PNP bipolar junction transistor with no integrated protection diodes, thermal shutdown, or current limiting. It contains only the three active semiconductor junctions (emitter-base-collector) in a SOT-223 package. External flyback diodes, base current limiting resistors, and thermal monitoring circuits must be added by the designer. The NZT45H8 relies entirely on external circuitry for safe operation in inductive or high-voltage applications.

What is the typical DC current gain (h_FE) of the NZT45H8 at different operating points?

The NZT45H8 exhibits h_FE = 60 minimum at I_C = −2.0 A and V_CE = −1.0 V, and h_FE = 40 minimum at I_C = −4.0 A and V_CE = −1.0 V. Gain decreases with increasing current and temperature, and varies between individual units. For reliable bias design, engineers should use the lower bound (40) at full load and verify stability across −55 °C to +125 °C operating range. The NZT45H8 does not specify guaranteed h_FE at I_C = −8 A.

Can the NZT45H8 be used as a direct replacement for the D45H8?

No, the NZT45H8 is not a direct replacement for the D45H8. While electrically similar, they differ in package (SOT-223 vs. TO-220), thermal performance (R_θJA = 83.3 °C/W vs. 62.5 °C/W), and power dissipation (1.5 W vs. 60 W). The NZT45H8 cannot handle the same power levels without significant derating and PCB redesign. Substituting NZT45H8 for D45H8 requires verifying SOA, thermal layout, and drive capability-no PCB changes are possible without risk of overheating or failure.

What is the recommended soldering profile for the NZT45H8 SOT-223 package?

The NZT45H8 SOT-223 package conforms to JEDEC J-STD-020 moisture sensitivity level (MSL) 1, allowing unlimited floor life at ≤30 °C/85% RH. Reflow soldering should follow IPC/JEDEC J-STD-020D: peak temperature ≤260 °C, time above liquidus 60–150 seconds, ramp-up rate ≤3 °C/s. Hand soldering requires ≤350 °C tip temperature for <5 seconds per joint. Exceeding these limits risks delamination or bond wire damage. Always refer to the latest ON Semiconductor packaging specification for the NZT45H8 before production release.