Diodes Incorporated ZTX853STZ

Overview

ZTX853STZ 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, P_tot = 1.2 W at T_amb = 25°C, and V_CE(sat) as low as 140 mV at I_C = 2 A / I_B = 100 mA - used in industrial DC-DC converter switching stages and motor drive half-bridge emitter followers.

For engineers reviewing the ZTX853STZ datasheet, ZTX853STZ pinout, ZTX853STZ application, or ZTX853STZ equivalent, key selection criteria include verified V_CEO derating above 100°C, pulsed I_CM capability under ≤2% duty cycle, h_FE stability across 10 mA–4 A, and TO-92-compatible thermal resistance (R_th(j-amb) = 150°C/W).

Technical Context

This discrete NPN bipolar junction transistor operates in linear or saturated switching mode with base-driven current control. Its design supports high-current pulse handling (10 A peak) and low-saturation operation critical for efficiency-sensitive power stage designs.

Electrical behavior is characterized by three h_FE tiers: 200 min at I_C = 10 mA, 100 min at I_C = 2 A, and 30 min at I_C = 4 A - confirming gain compression under high load, while f_T = 130 MHz enables usable bandwidth in fast-switching applications up to ~10 MHz.

Key Specifications

Pinout & Package

Package: TO-92 (E-Line compatible), molded plastic case with 3 leads. Standard lead configuration: Emitter (E), Base (B), Collector (C) - 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 high-current switching applications.

Compared with ZTX853STZ, ZTX851STZ trades voltage headroom for slightly lower cost but cannot replace it in 100 V applications, while BCX56-10 lacks both current and voltage ratings - making ZTX853STZ the sole option for 4 A/100 V single-device solutions in space-constrained TO-92 layouts.

Availability

ZTX853STZ is available at Aetrix Electronics and suitable for industrial motor drives, DC-DC converters, and relay interface modules requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for ZTX853STZ 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 the U.S.

ZTX853STZ belongs to the ZTX series of high-current bipolar transistors engineered for ruggedized industrial switching, emphasizing low saturation voltage, wide temperature operation, and TO-92 mechanical compatibility.

FAQ

What is the maximum allowable junction temperature for ZTX853STZ?

The absolute maximum junction temperature is +200°C, as specified in the Thermal Characteristics table. Operation at this limit requires strict thermal management - including PCB copper area ≥1 inch², ambient temperature ≤70°C, and no sustained power dissipation above 0.6 W without forced airflow or heatsinking.

Can ZTX853STZ be used in linear amplifier applications?

Yes, but with caution: its h_FE varies significantly (30–300) across collector current, and f_T = 130 MHz supports small-signal amplification up to ~10 MHz. For linear use, bias must be stabilized against thermal runaway using emitter degeneration resistors and adequate heatsinking due to R_th(j-amb) = 150°C/W.

Is ZTX853STZ RoHS compliant and halogen-free?

Yes - Diodes Incorporated confirms ZTX853STZ meets RoHS Directive 2011/65/EU and is halogen-free per IEC 61249-2-21. The "STZ" suffix denotes tape-and-reel packaging with RoHS-compliant matte tin lead finish and green molding compound.

What is the recommended PCB layout for optimal thermal performance?

Use ≥1 inch² of 2 oz copper connected directly to the collector lead (pin 3) with multiple thermal vias to inner/ground planes. Keep base and emitter traces short and wide; avoid routing high-dv/dt signals near the base. Maintain ≥0.5 mm clearance between collector pad and adjacent traces to prevent arcing at 100 V.