Diodes Incorporated ZDT619TA

Overview

ZDT619TA from Diodes Incorporated is a dual NPN medium-power high-gain transistor in SM-8 (SOT-223-8) package, designed for discrete switching and linear amplification in compact power stages. It features V_CEO = 50 V, I_C = 2 A per transistor, h_FE = 200–400 at I_C = 10 mA–2 A, f_T = 100–165 MHz, and operates from –55 °C to +150 °C - used in DC-DC converter current sensing and dual-channel load switching.

For engineers reviewing the ZDT619TA datasheet, ZDT619TA pinout, ZDT619TA application, or ZDT619TA equivalent, key selection criteria include verified dual-die thermal derating (20 mW/°C when both transistors active), confirmed V_CE(sat) ≤ 220 mV at I_C = 2 A / I_B = 50 mA, validated h_FE consistency across I_C = 10 mA–2 A, and SM-8 package pin mapping with isolated collectors and shared thermal pad.

Technical Context

The ZDT619TA integrates two independent NPN silicon transistors on a single die substrate within an SM-8 thermally enhanced leadframe. Each transistor supports full 50 V breakdown ratings (V_CBO, V_CEO, V_EBO) and shares a common thermal path via the exposed copper pad.

Its high h_FE range (200–400) and low V_CE(sat) (12–220 mV) enable efficient low-voltage switching in synchronous rectifier drivers and dual-emitter follower configurations, while f_T ≥ 100 MHz supports moderate-frequency signal amplification up to 165 MHz under 50 mA bias.

Key Specifications

Pinout & Package

Package: SM-8 (8-lead SOT-223 variant) with exposed thermal pad; thermally optimized for PCB-mounted power dissipation. Pin 1–4 and 5–8 form two identical NPN transistor structures sharing no internal connection except substrate thermal coupling.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ZDT619TA, ZXTD619N trades gain for higher voltage rating, while DMT6009LPS eliminates base drive entirely but forfeits linear region control and thermal matching between channels.

Availability

ZDT619TA is available at Aetrix Electronics and suitable for DC-DC converter current sensing, synchronous rectifier driver stages, and dual-channel industrial load switching requiring stable component supply across extended temperature and long-lifecycle programs.

Supply support for ZDT619TA 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 and signal integrity solutions for industrial, automotive, and computing markets.

The ZDT series targets medium-power discrete replacement applications, emphasizing thermal performance, gain consistency, and dual-device integration in surface-mount packages for space-constrained power stages.

FAQ

What is the maximum safe operating current per transistor in continuous mode?

The ZDT619TA supports 2 A continuous collector current per transistor at T_amb = 25 °C with adequate PCB copper (2-inch²). Derating applies above 25 °C at 20 mW/°C when both transistors are active, limiting usable current to ~1.5 A at 75 °C ambient with standard layout.

Can the two transistors be operated with different bias conditions simultaneously?

Yes - the ZDT619TA's dual NPN structure has electrically isolated collectors, bases, and emitters. Transistor 1 and Transistor 2 may be biased independently (e.g., one in saturation, one in active mode) without crosstalk, provided shared thermal limits (2.5 W total) are observed.

Is the exposed thermal pad internally connected to any pin?

No - the exposed thermal pad in the SM-8 package is electrically isolated and serves only for thermal conduction to the PCB. It must be soldered to a dedicated copper pour with thermal vias; no electrical connection to C1, C2, or substrate is present per Diodes Incorporated package drawings.

Does the ZDT619TA support pulsed operation beyond its continuous ratings?

Yes - the datasheet specifies I_CM = 6 A peak pulse current under pulsed conditions (300 µs width, ≤2 % duty cycle). This enables short-duration overload handling in motor drive fault protection or surge current limiting circuits without thermal runaway.