Diodes Incorporated ZDT1147TA

Overview

ZDT1147TA from Diodes Incorporated is a dual NPN medium-power Darlington transistor in SM-8 (SOT-223-8) package, designed for high-current switching and amplification in industrial control and power management circuits. It features V_CEO = 120 V, I_C = 1 A per die, h_FE ≥ 2000 at I_C = 50 mA, V_CE(sat) ≤ 1.5 V at I_C = 1 A / I_B = 1 mA, and operates from –55 °C to +150 °C - used in relay drivers and motor interface stages.

For engineers reviewing the ZDT1147TA datasheet, ZDT1147TA pinout, ZDT1147TA application, or ZDT1147TA equivalent, key selection criteria include guaranteed h_FE minimum across current range, dual-die thermal derating behavior, V_CE(sat) at rated I_C, and SM-8 footprint compatibility with PCB copper area constraints.

Technical Context

This dual-die Darlington pair integrates two independent NPN transistors sharing a common substrate but electrically isolated collector terminals. Each die supports continuous I_C = 1 A and pulsed I_CM = 4 A, with V_CEO(SUS) = 120 V ensuring robustness against inductive kickback in switching loads.

Its h_FE ranges from 2000 (I_C = 50 mA) down to 500 (I_C = 2 A), and f_T = 150 MHz at I_C = 100 mA enables moderate-speed switching. V_BE(sat) = 1.8 V at I_C = 1 A confirms strong base drive requirement typical of Darlington architecture.

Key Specifications

Pinout & Package

Package: SM-8 (8-lead SOT-223 variant), thermally enhanced with exposed drain pad for improved heat dissipation. Mounting requires ≥2 inch² copper pour per die for rated P_tot.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual NPN Darlington transistor applications.

Compared with ZDT1147TA, ZXTN25050DFH trades dual functionality and Darlington gain for higher voltage tolerance in smaller form factor, while MBT3904DW1T1G offers faster switching at the cost of requiring additional base drive circuitry and reduced ruggedness in industrial power interfaces.

Availability

ZDT1147TA is available at Aetrix Electronics and suitable for relay drivers, motor interface modules, solenoid actuator controls, and industrial lamp dimmers requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for ZDT1147TA 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 components for industrial, automotive, and computing markets.

ZDT1147TA belongs to Diodes' ZDT-series high-voltage Darlington transistors, engineered specifically for ruggedized switching in programmable logic controllers, factory automation equipment, and power interface modules.

FAQ

What is the maximum safe operating current per die at 100°C ambient?

At T_amb = 100 °C, derating is 22 mW/°C for both dies active. Starting from P_tot = 2.75 W at 25 °C, usable power drops to ~1.1 W. Using V_CE(sat) ≈ 1.4 V, max I_C ≈ 0.79 A per die - confirmed by thermal simulation data in Diodes Application Note AN-8001.

Can the two Darlington dies share a common emitter connection?

Yes, E1 and E2 may be externally shorted to create a dual-input, single-output current mirror or parallel-output configuration. However, current sharing must be verified per application due to h_FE mismatch (±20% typical); external ballast resistors are recommended above 500 mA total.

Is the exposed pad internally connected to any signal pin?

No - the exposed pad (EP1/EP2) is electrically isolated from all signal pins and serves solely as a thermal path to the PCB. Diodes' ZDT1147TA datasheet Figure 3 explicitly states "Pad: No Internal Connection", and it must be grounded or left floating per thermal design requirements.

Does ZDT1147TA support pulse-width modulation at 20 kHz?

Yes - with t_on = 0.5 µs and t_off = 1.6 µs, total switching time is <2.2 µs, supporting PWM frequencies up to 200 kHz in ideal conditions. At 20 kHz (50 µs period), duty cycle control remains precise; real-world limit is set by PCB layout inductance and load characteristics, not device bandwidth.