Diodes Incorporated ZTX853STOA

Overview

ZTX853STOA from Diodes Incorporated is an NPN silicon planar medium-power high-current transistor with V_CEO = 100 V, I_C = 4 A continuous, 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. It is used in industrial switching, linear power regulation, and relay driver circuits where robust current handling and low saturation loss are required.

For engineers reviewing the ZTX853STOA datasheet, ZTX853STOA pinout, ZTX853STOA application, or ZTX853STOA equivalent, key selection criteria include verified V_CEO rating, pulsed I_CM = 10 A capability, h_FE ≥ 100 at I_C = 2 A, thermal resistance R_th(j-amb) = 150 °C/W, and TO-92-compatible E-Line package mechanical compatibility.

Technical Context

This discrete NPN bipolar junction transistor operates in active, saturation, and cutoff regions with a transition frequency f_T of 130 MHz at I_C = 100 mA and V_CE = 10 V. Its safe operating area (SOA) supports single-pulse operation up to 10 A with defined voltage/current limits across pulse widths from 0.1 ms to 1 s.

The device features low V_CE(sat) (140–200 mV) under high-current drive conditions (I_C = 2–4 A), enabled by optimized base doping and emitter geometry. Thermal performance is characterized by R_th(j-case) = 50 °C/W and R_th(j-amb) = 150 °C/W on a 1-inch² PCB copper pad, supporting stable operation from –55°C to +200°C junction temperature.

Key Specifications

Pinout & Package

Package: TO-92-compatible E-Line (3-lead plastic package, lead configuration C-B-E when viewed with flat side facing user and leads downward).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar NPN high-current switching applications.

Compared with ZTX853STOA, ZTX851STOA trades voltage/current headroom for cost reduction in lower-tier systems, while BCX56-16 offers tighter h_FE tolerance but cannot sustain the 4 A continuous load or 100 V isolation required in industrial power interfaces.

Availability

ZTX853STOA is available at Aetrix Electronics and suitable for industrial relay drivers, linear power regulators, motor start circuits, and overcurrent protection switches requiring stable component supply across extended temperature ranges and high-current reliability.

Supply support for ZTX853STOA 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, signal integrity, and protection solutions for industrial and automotive markets.

ZTX853STOA belongs to the ZTX series of high-current bipolar transistors designed specifically for ruggedized switching and linear regulation in harsh-environment applications demanding wide temperature operation and proven SOA performance.

FAQ

What is the maximum safe continuous collector current for ZTX853STOA at 75°C ambient?

At T_amb = 75°C, derating begins at 25°C using R_th(j-amb) = 150 °C/W. With T_j(max) = 200°C, allowable ΔT = 125°C, so P_tot = 125/150 ≈ 0.83 W. Using V_CE(sat) ≈ 0.16 V at I_C = 2 A, max I_C ≈ √(P_tot/R_CE(sat)) yields ~3.2 A continuous under forced-air-cooled conditions.

Can ZTX853STOA replace a 2N3055 in a linear regulator design?

No - the 2N3055 is a much higher-power TO-3 device (I_C = 15 A, P_tot = 115 W). ZTX853STOA is rated for 4 A/1.2 W and uses TO-92 packaging. It may serve in low-power linear regulators (<3 A, <15 V), but not as a direct substitute in high-current, high-voltage applications where thermal mass and dissipation differ fundamentally.

Is ZTX853STOA RoHS compliant and halogen-free?

Yes - Diodes Incorporated confirms ZTX853STOA meets RoHS Directive 2011/65/EU and is halogen-free per IEC 61249-2-21. The device carries the "Green" designation in official documentation and is manufactured using lead-free solderable terminations compatible with standard reflow profiles.

What is the recommended minimum base drive current to ensure saturation at I_C = 4 A?

With h_FE ≥ 100 at I_C = 4 A and V_CE = 2 V, minimum I_B = I_C/h_FE = 40 mA. However, datasheet specifies V_CE(sat) = 160 mV at I_B = 400 mA, indicating forced β = 10 is used for guaranteed saturation. Therefore, 400 mA base drive is recommended for full 4 A load switching with low V_CE(sat).