Diodes Incorporated FZT603TA

Overview

FZT603TA from Diodes Incorporated is an 80V NPN Darlington transistor in SOT223 package, designed for high-current switching applications with BV_CEO > 80 V, I_C = 2 A continuous, h_FE up to 15,000 at 50 mA, V_CE(sat) = 0.79 V at 250 mA/0.25 mA drive, and automotive-qualified reliability per AEC-Q standards. It serves as a high-gain power switch in industrial motor drivers and relay interface circuits.

For engineers reviewing the FZT603TA datasheet, FZT603TA pinout, FZT603TA application, or FZT603TA equivalent, key selection criteria include its 80 V V_CEO, 2 A continuous collector current, SOT223 thermal performance (R_θJA = 41.7 °C/W on 50 mm × 50 mm 2 oz Cu), Darlington gain structure, and RoHS-compliant green packaging.

Technical Context

The FZT603TA implements a monolithic NPN Darlington pair with integrated base-emitter resistor network absent - requiring external base drive control. Its high h_FE (3,000–15,000 across 50 mA–6 A) enables low-base-current switching of inductive loads while maintaining V_CE(sat) ≤ 0.99 V up to 2 A.

Thermal design relies on the SOT223 lead-frame construction: R_θJL = 12.9 °C/W and R_θJC = 1.1 °C/W (2 oz Cu) support sustained 2 A operation with proper PCB copper area. ESD robustness includes 2 kV HBM and 200 V MM ratings per JEDEC JESD22-A114/A115.

Key Specifications

Pinout & Package

Package: SOT223 (Type DN), surface-mount, 4-terminal plastic molded case with exposed collector tab for thermal conduction. Weight: 0.112 g. Moisture sensitivity level: J-STD-020 Level 1.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ZTX1048A and MJD122, the FZT603TA delivers superior gain-to-voltage ratio (h_FE/V_CEO ≈ 188) and optimized SOT223 thermal efficiency (R_θJA = 41.7 °C/W), making it ideal for compact, high-reliability 48 V industrial switches where drive simplicity and thermal margin are critical.

Availability

FZT603TA is available at Aetrix Electronics and suitable for industrial relay drivers, DC motor control stages, LED array power switches, and power supply enable circuits requiring stable component supply, long-lifecycle support, and RoHS-compliant green packaging.

Supply support for FZT603TA 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, manufacturing, and sales operations across Asia, Europe, and the Americas.

The FZT603TA belongs to Diodes' high-voltage bipolar transistor product line, engineered for industrial and automotive-grade power switching applications demanding high gain, rugged voltage tolerance, and thermally efficient SMT packaging.

FAQ

What is the maximum continuous collector current for FZT603TA, and what PCB layout is required to sustain it?

The FZT603TA supports 2 A continuous collector current when mounted on a 50 mm × 50 mm 2 oz copper area on FR4 PCB, per Note 5 in the datasheet. This layout achieves R_θJA = 41.7 °C/W, limiting junction temperature rise to ≤83 °C at 3 W dissipation. Smaller copper areas increase thermal resistance and require current derating per Figure 5.

Does FZT603TA have an integrated base resistor, and how should base drive be designed?

No, FZT603TA has no internal base resistor. Base drive must be externally current-limited: for 2 A collector current, typical base current is 20 mA (per V_BE(sat) and h_FE data), so a 220 Ω resistor is appropriate from a 5 V MCU GPIO. Ensure base drive remains within I_B = 20 mA max to avoid overstress.

How does FZT603TA's Darlington configuration affect switching speed and power loss?

The Darlington structure increases h_FE but introduces higher V_CE(sat) (0.79–1.13 V) and slower turn-off time (t_off = 1.6 µs). This makes it unsuitable for >10 kHz PWM but optimal for DC or low-frequency switching where conduction loss dominates over switching loss - e.g., relay coils and motor enable signals.

Is FZT603TA suitable for automotive applications, and what is the qualification status?

The FZT603TA shares the same die and process as the AEC-Q200-qualified FZT603Q, but FZT603TA itself is not certified. It is rated for -55 °C to +150 °C operation and qualified to JEDEC reliability standards referenced in AEC-Q; however, automotive end-equipment use requires formal FZT603Q procurement and PPAP documentation.