Diodes Incorporated ZTX689B

Overview

ZTX689B from Diodes Incorporated is an NPN silicon planar medium-power high-gain transistor rated for 20 V V_CEO, 3 A continuous collector current, and 400 h_FE at I_C = 2 A; it delivers 0.1 V typical V_CE(sat) at I_C = 0.1 A / I_B = 0.5 mA and supports motor drivers, flash gun converters, and Darlington pair configurations in battery-powered systems.

For engineers reviewing the ZTX689B datasheet, ZTX689B pinout, ZTX689B application, or ZTX689B equivalent, key selection factors include its low saturation voltage (0.1–0.5 V), high DC current gain (up to 500 at 0.1 A), TO-92 package thermal resistance (70 °C/W junction-to-case), and suitability for medium-power switching in thermally constrained PCB layouts.

Technical Context

The ZTX689B operates as a medium-power NPN bipolar junction transistor with a maximum V_CEO of 20 V and I_C rating of 3 A, optimized for linear and saturated switching modes. Its h_FE spans 150–500 across I_C = 0.1–6 A, supporting both high-current drive and precision biasing.

Thermal design relies on its 70 °C/W junction-to-case resistance and 116–175 °C/W junction-to-ambient ratings depending on PCB copper area (≥1 inch²). It achieves 150 MHz f_T at I_C = 50 mA / V_CE = 5 V, enabling use in audio-frequency switching and pulse applications up to ~100 kHz.

Key Specifications

Pinout & Package

Package: TO-92 (E-Line compatible), through-hole, plastic encapsulated, 3-pin vertical mounting. Standard lead configuration with emitter (E), base (B), 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 NPN medium-power switching applications.

Compared with ZTX653 and MPSA42, the ZTX689B uniquely balances 20 V breakdown, 3 A current, and 400 h_FE in TO-92-making it optimal for cost-sensitive, thermally constrained 12–20 V battery-powered switches where gain and saturation voltage are critical.

Availability

ZTX689B is available at Aetrix Electronics and suitable for motor drivers, flash gun converters, Darlington replacement circuits, and battery-powered portable electronics requiring stable component supply and long-term manufacturability.

Supply support for ZTX689B 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 power management and signal integrity solutions for industrial and consumer markets.

The ZTX689B belongs to Diodes' legacy high-gain bipolar transistor product line, engineered specifically for medium-power linear and switching applications where low saturation voltage and robust thermal performance are essential.

FAQ

What is the maximum safe operating temperature for the ZTX689B?

The ZTX689B has a specified junction temperature range of –55°C to +200°C. Its absolute maximum storage and operating temperature is +200°C, but sustained operation above +150°C requires derating per the thermal impedance curves in the datasheet. At ambient temperatures exceeding +100°C, PCB copper area and airflow become critical to maintain T_j < 200°C.

Can the ZTX689B be used in linear amplifier applications?

Yes-the ZTX689B supports linear operation with h_FE stability across I_C = 0.1–6 A and V_CE = 2 V, and its 150 MHz f_T allows audio-frequency amplification. However, its 1.5 W practical PCB power dissipation limit and thermal resistance require careful heatsinking for Class-A stages above ~500 mW output.

Is the ZTX689B RoHS compliant and halogen-free?

Yes-Diodes Incorporated certifies the ZTX689B as RoHS compliant and halogen-free per their official product change notices and material declarations. The TO-92 package uses lead-free matte tin plating, and the device meets JEDEC J-STD-609 Category 1 for halogen content (<900 ppm bromine, <900 ppm chlorine).

How does the ZTX689B's Safe Operating Area (SOA) compare to standard TO-92 transistors?

The ZTX689B's SOA extends to 2 A at 10 V (DC) and 8 A at 10 V (100 µs pulses), significantly wider than typical TO-92 devices due to its 70 °C/W R_th(j-case) and robust bond wire construction. This enables reliable inductive switching in motor and relay loads without secondary breakdown concerns below 20 V.