Diodes Incorporated ZX5T851A

Overview

ZX5T851A from Zetex (now Diodes Incorporated) is a 60V NPN medium-power bipolar junction transistor in E-line package, designed for low-loss switching in DC-DC converters and power drive circuits. It delivers 4.5A continuous collector current, 15A peak pulse current, and ultra-low V_CE(SAT) of 45mV at I_C=5A/I_B=200mA, enabling high-efficiency motor and solenoid control in industrial power modules.

For engineers reviewing the ZX5T851A datasheet, ZX5T851A pinout, ZX5T851A application, or ZX5T851A equivalent, key selection criteria include verified saturation voltage at rated current, thermal resistance under defined PCB mounting conditions, h_FE consistency across 1–5A operating range, and E-line mechanical compatibility with automated through-hole assembly.

Technical Context

This NPN transistor employs optimized base doping and emitter geometry to achieve R_SAT = 34 mΩ at 5A, supporting high-duty-cycle switching without thermal runaway. Its BVCBO = 150V and BVCEO = 60V enable robust operation in 48V bus systems with transient margin.

With f_T = 130 MHz and t_ON/t_OFF = 42/760 ns under 1A switching, it supports medium-frequency PWM control (≤100 kHz) while maintaining low switching losses in relay drivers and backlight inverters.

Key Specifications

Pinout & Package

E-line through-hole package (TO-92 variant), 3-pin straight lead configuration with standard emitter-base-collector terminal order. Package outline conforms to Zetex E-line mechanical drawing: L=13.0–13.97 mm, D=4.37–4.77 mm, body height ≈4.0 mm.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar NPN medium-power switching applications.

Compared with ZTX851 and MJD122G, ZX5T851A uniquely balances ultra-low saturation voltage, high h_FE, and E-line compatibility-making it optimal for compact, thermally constrained DC-DC and actuator driver designs where efficiency and PCB real estate are critical.

Availability

ZX5T851A is available at Aetrix Electronics and suitable for emergency lighting control, DC fan motor driving, solenoid actuator interfacing, and CCFL backlight inverter designs requiring stable component supply and long-term industrial availability.

Supply support for ZX5T851A 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 (acquired by Diodes Incorporated in 2008) specialized in high-performance analog and discrete semiconductors for power management and signal conditioning.

The ZX5T851A belongs to Zetex's E-line low-saturation NPN transistor family, engineered specifically for high-efficiency, medium-current switching in space-constrained industrial and automotive auxiliary power systems.

FAQ

What is the maximum safe operating temperature for ZX5T851A?

The ZX5T851A has a specified junction temperature range of –55°C to +150°C. Under continuous 4.5A operation with R_JA = 125°C/W on a 25×25 mm FR4 PCB, junction temperature remains below 125°C at 60°C ambient-well within safe limits for industrial use.

Can ZX5T851A be used in avalanche mode?

No. The device is not rated or characterized for avalanche energy handling. Its absolute maximum BV_CER = 150V applies only under specified test conditions with external base resistor limiting; intentional avalanche operation may cause parametric shift or failure.

Is ZX5T851A RoHS compliant?

Yes. As a Zetex product issued in November 2003 and manufactured prior to EU RoHS exemption sunset dates for certain discrete transistors, ZX5T851A meets RoHS Directive 2011/65/EU requirements with lead-free terminations and compliant molding compound.

What is the recommended base resistor value for 5A switching?

For guaranteed saturation at I_C = 5A, apply I_B ≥ 200 mA. With V_BE(SAT) ≈ 1.05 V and typical 5V logic drive, a 20 Ω ±5% resistor delivers 200 mA while accounting for trace resistance and temperature derating.