Diodes Incorporated ZTX855STZ

Overview

ZTX855STZ from Diodes Incorporated is a 150V NPN medium-power transistor in E-Line (TO-92 compatible) package, rated for 4A continuous collector current and 10A peak pulse current, with V_CE(sat) ≤ 60 mV at 4A/400mA drive, operating up to +200°C junction temperature, and used in high-voltage switching power supplies and industrial motor control stages.

For engineers reviewing the ZTX855STZ datasheet, ZTX855STZ pinout, ZTX855STZ application, or ZTX855STZ equivalent, key selection criteria include its 150V V_CEO, low 60 mV saturation voltage at full 4A load, AEC-Q101 qualification for automotive-grade reliability, and E-Line thermal performance with R_ΘJC = 50°C/W.

Technical Context

This NPN bipolar junction transistor is optimized for medium-power linear and switching applications where high breakdown voltage and robust thermal capability are required. It features complementary pairing with ZTX955 and supports pulsed operation up to 10A with f_T = 90 MHz for moderate-frequency switching.

Its E-Line package provides TO-92 compatibility while enabling higher power dissipation (1.58 W at seating plane) than standard TO-92 devices. The device meets JEDEC Class 3A HBM ESD rating (≥4 kV) and operates across –55°C to +200°C, supporting harsh-environment designs.

Key Specifications

Pinout & Package

E-Line (TO-92 compatible) molded plastic package with matte tin-plated leads; weight ≈ 0.159 g; UL 94V-0 flammability rating; flat-face marking orientation with ejection mark.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ZTX855STZ, ZTX851 trades voltage rating for cost in low-voltage industrial controls, while MJD127 offers higher current but demands thermal management and board real estate-neither matches the 150V/4A/E-Line combination in a single package.

Availability

ZTX855STZ is available at Aetrix Electronics and suitable for industrial motor control, switching power supply design, and automotive lighting applications requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant sourcing.

Supply support for ZTX855STZ 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, application-optimized components for automotive, industrial, and computing markets.

ZTX855STZ belongs to Diodes' E-Line medium-power transistor product line, designed specifically for high-voltage switching and ruggedized linear amplification in space-constrained, thermally demanding environments.

FAQ

What is the maximum continuous collector current for ZTX855STZ?

The ZTX855STZ is rated for 4 A continuous collector current at T_A = +25°C with specified PCB mounting conditions. Derating applies above +25°C ambient per the datasheet's thermal curves, and actual usable current depends on layout, copper area, and airflow. At 100°C ambient, maximum continuous I_C drops to approximately 2.4 A under standard test conditions.

Is ZTX855STZ pin-compatible with standard TO-92 transistors?

ZTX855STZ uses the E-Line package, which is mechanically TO-92 compatible but has joggled leads and specific pin-out (Emitter–Collector–Base on flat face). While footprint fits TO-92 sockets, the pin sequence differs from common TO-92 NPNs like BC547 (E-B-C), requiring PCB layout verification before substitution.

Does ZTX855STZ support automotive applications?

Yes-ZTX855STZ is qualified to AEC-Q101 standards, including stress tests for temperature cycling, humidity, and mechanical shock. Its –55°C to +200°C operating range, 4 kV HBM ESD rating, and green material composition make it suitable for under-hood lighting, body control, and engine management subsystems.

How does the E-Line package improve thermal performance over standard TO-92?

The E-Line package features a thicker lead frame and optimized internal bond wire geometry, achieving R_ΘJC = 50°C/W-significantly lower than typical TO-92 R_ΘJC (~100°C/W). This allows more heat to be conducted directly from the die through the collector lead to the PCB, enabling higher power dissipation (1.58 W vs. ~0.625 W for standard TO-92) under identical mounting conditions.