Diodes Incorporated ZTX853QSTZ

Overview

ZTX853QSTZ from Diodes Incorporated is an NPN silicon planar medium-power high-current transistor with V_CEO = 100 V, continuous I_C = 4 A, peak I_CM = 10 A, V_CE(sat) ≤ 160 mV at 4 A/400 mA drive, and P_tot = 1.2 W at T_amb = 25°C - used in industrial DC-DC converter switching stages and motor driver output stages.

For engineers reviewing the ZTX853QSTZ datasheet, ZTX853QSTZ pinout, ZTX853QSTZ application, or ZTX853QSTZ equivalent, key selection criteria include verified V_CEO/I_C derating behavior, low-saturation-voltage performance under pulsed 4 A loads, thermal resistance to ambient (150 °C/W), and TO-92-compatible leadform compatibility with legacy board layouts.

Technical Context

This discrete NPN bipolar junction transistor operates in linear or saturated switching mode, featuring a minimum h_FE of 100 at I_C = 10 mA and 20 at I_C = 4 A, enabling robust current amplification across wide load ranges. Its V_(BR)CEO = 100 V and V_(BR)CBO = 200 V support operation in 48 V bus systems with margin for inductive kickback.

Thermal design is constrained by R_th(j–amb) = 150 °C/W on standard 1-inch² PCB copper, requiring pulse-width-limited operation above 1 A continuous to avoid junction exceedance. Switching times (t_on = 50 ns, t_off = 1650 ns) reflect optimized base charge control for medium-speed switching up to ~100 kHz.

Key Specifications

Pinout & Package

Package: TO-92 compatible (E-Line 3-297 outline), through-hole, epoxy-molded plastic case with 3.3 mm pitch, rated for T_j = –55°C to +200°C.

Key Features

Applications

Availability

ZTX853QSTZ is available at Aetrix Electronics and suitable for industrial motor drivers, 48 V DC-DC converters, solenoid actuator interfaces, and overvoltage-protected relay drivers requiring stable component supply across multi-year production cycles.

Supply support for ZTX853QSTZ 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, headquartered in Plano, Texas, with design centers across Asia and manufacturing in China, Taiwan, and Malaysia.

ZTX853QSTZ belongs to the ZTX series of high-current bipolar transistors engineered for ruggedized industrial switching applications where reliability under thermal and electrical stress is critical.

FAQ

What is the maximum safe continuous collector current for ZTX853QSTZ at 70°C ambient?

At T_amb = 70°C, derating per the datasheet curve yields P_tot ≈ 0.84 W. With V_CE(sat) ≈ 150 mV at 4 A, max continuous I_C is ~2.3 A to maintain T_j ≤ 150°C. Operation above this requires forced airflow or copper area increase beyond 1 inch².

Does ZTX853QSTZ support direct microcontroller GPIO drive without a base resistor?

No - driving the base directly from a 3.3 V or 5 V GPIO risks excessive base current (>1 A peak) due to low V_BE(sat) (~960 mV) and high h_FE. A series base resistor (e.g., 10 Ω for 5 V drive) is mandatory to limit I_B to ≤400 mA and prevent latch-up or bond-wire failure.

How does ZTX853QSTZ compare to ZTX851 in terms of saturation voltage and current rating?

ZTX853QSTZ specifies V_CE(sat) ≤160 mV at 4 A/400 mA, while ZTX851 is rated for 2 A/200 mA with V_CE(sat) ≤500 mV. The ZTX853QSTZ delivers 2× continuous current and ~68% lower saturation voltage, enabling higher efficiency in high-load switching nodes.

Is ZTX853QSTZ suitable for linear regulator pass transistor applications?

No - its f_T = 130 MHz and h_FE variation (20–300) make it unsuitable for precision linear regulation. Designed for switching, not analog amplification; use instead complementary PNP/NPN pairs like ZTX653/ZTX753 for emitter-follower pass stages.