Diodes Incorporated FZT949TC

Overview

FZT949 from Diodes Incorporated is a 30V PNP medium-power transistor in SOT223 package, designed for high-current switching and linear amplification. It delivers -5.5A continuous collector current, -20A peak pulse current, and V_CE(sat) < -140mV at -1A, with h_FE ≥ 75 up to -5A. It is used in automotive body control modules for load switching of solenoids and relays.

For engineers reviewing the FZT949 datasheet, FZT949 pinout, FZT949 application, or FZT949 equivalent, key selection criteria include guaranteed h_FE hold-up at high current, JEDEC-qualified reliability, low saturation voltage under industrial temperature range (-55°C to +150°C), and RoHS-compliant "Green" packaging.

Technical Context

This PNP bipolar junction transistor operates in common-emitter configuration with specified BVCER ≥ -50V (with base-emitter resistor ≤ 1kΩ) and BVCEO ≥ -30V. Its gain remains stable across wide current range: h_FE = 100–300 at IC = -1A to -5A, supporting robust current amplification in feedback-regulated power stages.

Thermal performance is defined for two PCB mounting conditions: R_θJA = 42°C/W on 52mm × 52mm 2oz copper, and 78°C/W on 25mm × 25mm 1oz copper. Safe operating area (SOA) supports single-pulse operation up to -20A at -30V with 100µs width, enabling reliable surge handling in motor drive protection circuits.

Key Specifications

Pinout & Package

Package: SOT223 (Type DN), surface-mount, 4-pin outline with exposed collector tab (pin 3) for thermal conduction. Molded green compound, UL 94V-0 rated, 0.112g weight.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ZXTN25050DFH and MJD2955T4G, FZT949 uniquely balances SOT223 surface-mount compatibility, -5.5A continuous rating, and sub-140mV saturation at 1A-making it optimal for space-constrained automotive and industrial PCBs needing high-current PNP switching without discrete heatsinks.

Availability

FZT949 is available at Aetrix Electronics and suitable for automotive body control modules, industrial power sequencing circuits, DC motor brake control, and LED driver current sinks requiring stable component supply and AEC-Q aligned reliability.

Supply support for FZT949 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 semiconductor manufacturer specializing in discrete, analog, and mixed-signal solutions, with operations across Asia, Europe, and the Americas.

FZT949 belongs to Diodes' high-reliability PNP transistor product line, engineered for automotive and industrial applications demanding robust thermal performance, JEDEC-qualified stress endurance, and environmentally compliant packaging.

FAQ

What is the maximum safe operating temperature for FZT949?

The FZT949 has an operating junction temperature range of -55°C to +150°C. Its absolute maximum rating is defined by thermal limits: at 25°C ambient, 3.0W power dissipation is allowed on 52mm × 52mm 2oz copper; above 25°C, linear derating applies at 24mW/°C. Exceeding T_J = +150°C risks permanent parametric shift or bond-wire failure.

Is FZT949 pin-compatible with FZT949TA or FZT949Q?

Yes-FZT949, FZT949TA, and FZT949Q share identical SOT223 (Type DN) pinout and mechanical footprint. The suffixes denote packaging (TA = tape-and-reel), qualification level (Q = AEC-Q101 qualified), and marking variants; electrical specifications and pin functions are fully consistent across all versions.

How does FZT949's hFE behavior differ from standard small-signal PNP transistors?

Unlike small-signal devices whose h_FE drops sharply above 100mA, FZT949 maintains h_FE ≥ 75 at -5A and ≥ 35 at -20A due to optimized emitter geometry and doping profile. This enables predictable base current calculation across its entire rated current range, eliminating need for gain-compensated drive networks in high-power switching.

Can FZT949 be used in linear regulator applications?

Yes-its V_CE(sat) < -140mV at -1A and h_FE ≥ 100 at low currents support use as a pass transistor in adjustable linear regulators. However, thermal design must account for R_θJA = 42°C/W; for >1W dissipation, the exposed collector tab must be soldered to ≥ 52mm² of 2oz copper to avoid exceeding T_J = +150°C.