Diodes Incorporated ZDT705TA

Overview

ZDT705TA from Diodes Incorporated is a dual PNP medium-power Darlington transistor array in SM-8 (SOT-223-8) package, rated for V_CEO = −120 V, I_C = −1 A continuous per die, and P_tot = 2.75 W with both dies active. It delivers h_FE ≥ 3000 at I_C = −10 mA and supports high-gain switching in industrial relay drivers and DC motor control circuits.

For engineers reviewing the ZDT705TA datasheet, ZDT705TA pinout, ZDT705TA application, or ZDT705TA equivalent, key selection criteria include guaranteed V_CEO(SUS) = −120 V, low V_CE(sat) = −1.3 V at I_C = −1 A / I_B = −1 mA, dual-die thermal derating (22 mW/°C), and validated operation from −55°C to +150°C.

Technical Context

The ZDT705TA integrates two independent PNP Darlington transistors on a single SM-8 substrate, each with built-in base-emitter resistors omitted-requiring external base drive. Its Darlington configuration provides high DC current gain (h_FE up to 30k at low I_C) while maintaining robust avalanche-rated V_CEO(SUS) = −120 V under inductive switching.

Thermal design leverages shared copper pad dissipation: total P_tot rises from 2.25 W (single die active) to 2.75 W (both active), with corresponding junction-to-ambient thermal resistance dropping from 55.6 °C/W to 45.5 °C/W-enabling higher aggregate power handling without forced air.

Key Specifications

Pinout & Package

Package: SM-8 (8-lead SOT-223 variant), surface-mount, thermally enhanced with exposed copper pad for heatsinking. Dual-die layout enables independent channel routing or paralleled operation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual PNP Darlington switching applications.

Compared with ZXTP2025E6 and MBT3906DW1T1G, the ZDT705TA uniquely combines dual-channel integration, −120 V avalanche tolerance, and Darlington-level gain-making it the only option among the three qualified for standalone 120 V relay and solenoid control without auxiliary protection or gain stages.

Availability

ZDT705TA is available at Aetrix Electronics and suitable for industrial relay drivers, DC motor direction control, solenoid actuator interfaces, and lamp/LED string dimming requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for ZDT705TA 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 devices for industrial and automotive markets.

The ZDT705TA belongs to Diodes' high-voltage Darlington transistor product line, engineered specifically for ruggedized, high-gain switching in thermally demanding industrial control and electromechanical actuation systems.

FAQ

Is ZDT705TA pin-compatible with ZDT704TA?

No. ZDT705TA uses an SM-8 (SOT-223-8) package with eight leads and dual isolated collectors/emitters/bases. ZDT704TA is housed in a smaller SOT-23-6 package with different pin mapping and lower power ratings (P_tot = 1.25 W). Physical and electrical incompatibility prevents direct replacement.

Can ZDT705TA replace mechanical relays entirely?

ZDT705TA can replace electromechanical relays in low-energy switching applications (e.g., ≤1 A, ≤120 V resistive/inductive loads) where lifetime, noise, and size matter-but it does not provide galvanic isolation. External optocouplers or isolated gate drivers remain necessary for safety-critical or high-isolation requirements.

What is the maximum safe switching frequency for ZDT705TA?

Based on measured t_on = 0.6 µs and t_off = 0.8 µs, the device supports clean switching up to ~500 kHz in low-duty-cycle pulse applications. For continuous PWM (e.g., motor control), thermal limits constrain practical operation to ≤20 kHz with adequate copper area and ambient ≤70°C.

Does ZDT705TA require base-emitter resistors for stability?

No internal base-emitter resistors are integrated. External base resistors are mandatory to set I_B and prevent thermal runaway. Recommended values range from 1 kΩ to 10 kΩ depending on drive voltage and target I_C; see Figure 3 in the original datasheet for safe operating area boundaries.