Diodes Incorporated ZTX968

Overview

ZTX968 from Zetex Semiconductors (now Diodes Incorporated) is a PNP silicon planar medium-power high-current bipolar junction transistor rated for −4.5 A continuous collector current, −12 V V_CEO, and 1.2 W power dissipation at 25°C ambient. It delivers low saturation voltage (−100 mV typ. at I_C = −2 A, I_B = −50 mA), high DC current gain (h_FE = 450 min at I_C = −500 mA), and operates across −55°C to +200°C junction temperature - used in industrial linear regulators and high-side switch circuits.

For engineers reviewing the ZTX968 datasheet, ZTX968 pinout, ZTX968 application, or ZTX968 equivalent, key selection criteria include verified PNP polarity, TO-92 package compatibility, guaranteed −20 A peak pulse rating, low V_CE(sat) under high-current switching, and thermal resistance of 150°C/W (junction-to-ambient) with standard PCB mounting.

Technical Context

The ZTX968 is a discrete PNP BJT optimized for medium-power linear and switching applications where high current drive and low on-state loss are required. Its design emphasizes robust safe operating area (SOA) up to −20 A pulsed, stable h_FE across wide current range (10 mA to 20 A), and low thermal resistance via TO-92 leadframe construction.

It features a Spice model for simulation validation, supports base-driven operation with fixed I_C/I_B ratios (e.g., 10–250), and exhibits predictable V_BE(on) (−830 to −1000 mV at I_C = −5 A), enabling accurate bias network design in analog power stages.

Key Specifications

Pinout & Package

Package: TO-92 (E-Line compatible), epoxy-molded, through-hole, 3-lead plastic case with standardized pin assignment (Emitter-Base-Collector left-to-right when flat side faces viewer).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar PNP high-current transistor applications.

Compared with MJD2955 and BCP53-16, the ZTX968 uniquely balances TO-92 mountability, −4.5 A continuous rating, and sub-200 mV saturation voltage - making it optimal for cost-sensitive, medium-power through-hole systems requiring both density and performance.

Availability

ZTX968 is available at Aetrix Electronics and suitable for industrial linear regulators, high-side load switches, DC motor driver stages, and overcurrent protection circuits requiring stable component supply and long-term manufacturability.

Supply support for ZTX968 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

Zetex Semiconductors was a UK-based analog and discrete semiconductor specialist acquired by Diodes Incorporated in 2008; known for high-performance BJTs, MOSFETs, and interface ICs targeting industrial and automotive markets.

The ZTX series was developed specifically for ruggedized medium-power discrete applications demanding reliability across extended temperature ranges and high-current transient tolerance.

FAQ

Is ZTX968 suitable for surface-mount assembly?

No - ZTX968 uses a through-hole TO-92 package with 0.1-inch lead spacing and is not designed for reflow soldering or pick-and-place automation. Its thermal performance relies on copper pad area and lead conduction; SMT alternatives like BCP53-16 should be used for automated production.

What is the maximum safe base current for continuous operation?

The absolute maximum base current is not explicitly specified, but design practice limits I_B to ≤200 mA (per I_C = −5 A, I_C/I_B = 25) to avoid bond wire overheating. Derating to 100 mA ensures long-term reliability under sustained load conditions.

Does ZTX968 require a heatsink at 3 A continuous current?

At 3 A with V_CE(sat) ≈ −150 mV, power dissipation is ~0.45 W. With R_th(j-amb) = 150°C/W, junction rise is ~68°C above ambient - acceptable without heatsink below 85°C ambient. For >60°C ambient or pulsed loads, a small copper pour (≥1 in²) is recommended.

Can ZTX968 replace NPN transistors in existing circuits?

No - ZTX968 is a PNP device with inverted polarity; direct substitution for NPN types (e.g., ZTX450) would reverse bias all junctions and prevent operation. Circuit topology must be redesigned to accommodate high-side switching and negative base drive requirements.