Diodes Incorporated ZTX718STZ

Overview

ZTX718STZ from Diodes Incorporated (formerly Zetex) is a PNP silicon planar medium-power high-gain bipolar junction transistor, designed for switching and linear amplification in power control stages. It delivers 2.5A continuous collector current, -20V V_CEO, and h_FE up to 475 at I_C = -10mA - enabling robust gate driving of complementary N-channel MOSFETs in DC-DC converters and motor control H-bridges.

For engineers reviewing the ZTX718STZ datasheet, ZTX718STZ pinout, ZTX718STZ application, or ZTX718STZ equivalent, key selection criteria include its low V_CE(sat) (-145mV typ. at I_C = -1.5A), pulsed I_CM of -6A, TO-92-compatible E-Line package thermal performance, and verified operation across -55°C to +200°C junction temperature range.

Technical Context

This PNP BJT operates in common-emitter configuration with fixed-base drive logic, supporting fast-switching applications via 40ns turn-on and 670ns turn-off times under pulsed conditions (300µs width, ≤2% duty cycle). Its h_FE remains stable across I_C = -10mA to -6A, and V_CE(sat) stays below -260mV even at I_C = -2.5A/IB = -200mA.

The device uses planar epitaxial construction with gold-doped base region to enhance minority-carrier lifetime and gain-bandwidth product (f_T = 150–180MHz). Thermal resistance is specified at 116°C/W (junction-to-ambient, 1 in² PCB copper), enabling reliable operation without heatsinking in medium-power pulse loads.

Key Specifications

Pinout & Package

Package: TO-92-compatible E-Line (lead-form variant), epoxy-molded, through-hole mounting. Standard pinout orientation with emitter (E), base (B), and collector (C) arranged left-to-right when flat side faces viewer and leads point downward.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar PNP medium-power switching applications.

Compared with MJD2955G, ZTX718STZ offers superior switching speed and gain uniformity for gate drive, while ZTX618STZ serves strictly as its matched NPN partner-not a functional substitute-making ZTX718STZ uniquely suited for single-ended high-speed PNP switching where footprint and thermal mass are constrained.

Availability

ZTX718STZ is available at Aetrix Electronics and suitable for motor control H-bridges, DC-DC converter gate drivers, and automotive engine control modules requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for ZTX718STZ 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 acquired Zetex plc in 2008, integrating its high-performance analog and discrete portfolio into a global semiconductor supplier focused on power management, signal integrity, and discrete solutions.

ZTX718STZ belongs to Zetex's legacy "ZTX" series of high-gain, high-speed bipolar transistors engineered specifically for power switching and precision analog interface applications in automotive, industrial, and computing systems.

FAQ

What is the maximum safe continuous power dissipation for ZTX718STZ on a standard PCB?

The maximum continuous power dissipation is 1.0 W at T_amb = 25°C when mounted on a PCB with ≥1 in² copper area. Derating is linear at 8.6 mW/°C above 25°C, reaching zero dissipation at ~140°C ambient - confirmed per the published derating curve and R_th(j-amb) = 116°C/W specification.

Can ZTX718STZ be used in parallel configurations for higher current handling?

No - ZTX718STZ lacks built-in emitter ballasting or matched h_FE binning required for stable current sharing. Its negative temperature coefficient of V_BE(sat) causes thermal runaway if paralleled without external emitter resistors or active current balancing circuitry.

Is ZTX718STZ RoHS compliant and halogen-free?

Yes - Diodes Incorporated certifies ZTX718STZ as RoHS 2011/65/EU compliant and halogen-free per IEC 61249-2-21, with lead-free matte tin plating on leads and fully compliant molding compound, as documented in Diodes' official material declarations.

Does ZTX718STZ require a base resistor when driven directly from a 3.3V MCU GPIO?

Yes - a series base resistor is mandatory. With V_BE(on) ≈ -0.9V and required I_B ≥200mA for full saturation at I_C = -2.5A, a 3.3V GPIO must use R_B ≤ (3.3V − 0.9V)/0.2A = 12Ω to ensure reliable turn-on; practical designs use 10Ω ±5% with adequate power rating.