Diodes Incorporated ZDT749TA

Overview

ZDT749TA from Diodes Incorporated is a dual PNP medium-power transistor in SM-8 (SOT-223-8) package, rated for V_CEO = −25 V, I_C = −2 A continuous per die, and P_tot = 2.75 W with both dies active. It delivers h_FE = 70–300 across I_C = −50 mA to −2 A and supports fast switching with t_on = 40 ns and t_off = 450 ns, commonly used in dual-channel DC-DC converter output stages.

For engineers reviewing the ZDT749TA datasheet, ZDT749TA pinout, ZDT749TA application, or ZDT749TA equivalent, key selection criteria include verified dual-die thermal coupling, guaranteed V_CE(sat) ≤ −0.5 V at I_C = −2 A/IB = −200 mA, h_FE binning at multiple current levels, and SM-8 footprint compatibility with high-current PCB layout practices.

Technical Context

The ZDT749TA integrates two matched PNP transistors on a single die substrate within an SM-8 thermally enhanced leadframe, enabling synchronous operation with shared thermal mass. Its V_BE(on) = −0.8 to −1.0 V at I_C = −1 A and V_CE = −2 V ensures predictable base drive requirements in linear and saturated switching modes.

With f_T = 100–160 MHz at I_C = −100 mA/V_CE = −5 V and C_obo = 55–100 pF at V_CB = −10 V, it supports high-frequency switching up to ~1 MHz in hard-switched topologies while maintaining stable gain under pulsed conditions (300 µs pulse width, ≤2% duty cycle).

Key Specifications

Pinout & Package

Package: SM-8 (8-lead SOT-223 variant), thermally optimized with exposed die pad for PCB heat sinking; leads are gull-wing surface-mount with dual emitter-collector-base symmetry.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ZXT749N and MBT3906DW1T1G, the ZDT749TA uniquely supports dual high-current PNP operation with validated thermal coupling and full-load V_CE(sat) specification-enabling compact, thermally efficient designs where polarity, current, and thermal co-location are mandatory.

Availability

ZDT749TA is available at Aetrix Electronics and suitable for DC-DC converter output stages, industrial relay drivers, automotive LED matrix controllers, and redundant power supply OR-ing requiring stable component supply and long-term manufacturability.

Supply support for ZDT749TA 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 and manufacturing operations across Asia and the Americas.

The ZDT749TA belongs to Diodes' high-reliability power transistor product line, engineered specifically for industrial and automotive power control applications demanding matched dual-transistor performance and extended temperature operation.

FAQ

What is the maximum allowable junction temperature for continuous operation?

The ZDT749TA has a specified operating junction temperature range of −55°C to +150°C. For continuous DC operation, thermal design must ensure T_j does not exceed +150°C under worst-case ambient and power dissipation conditions, using θ_JA = 45.5°C/W (both dies active) and appropriate PCB copper area.

Can the two transistors be operated at different current levels simultaneously?

Yes-the ZDT749TA allows independent biasing of each transistor. However, simultaneous operation at unequal currents causes asymmetric heating, reducing effective thermal resistance margin. Datasheet derating curves assume equal loading; for mixed loads, use θ_JA = 55.6°C/W (single die on) as conservative basis.

Is the SM-8 package RoHS-compliant and lead-free?

Yes, the ZDT749TA is manufactured in a RoHS-compliant, lead-free SM-8 package per Diodes Incorporated's standard qualification. The device meets JEDEC J-STD-020 moisture sensitivity level MSL3 and supports standard Pb-free reflow profiles with peak temperature ≤260°C.

Does the datasheet specify SOA (Safe Operating Area) curves?

No, the official ZDT749TA datasheet (Issue 1, November 1995) does not include SOA graphs. Designers must rely on absolute maximum ratings (V_CEO, I_C, P_tot) and thermal derating guidelines, applying safety margins for inductive switching or transient overloads per application-specific stress analysis.