Diodes Incorporated FZT955TA

Overview

FZT955TA from Diodes Incorporated is a PNP silicon planar high-current bipolar junction transistor in SOT-223 package, rated for −4 A continuous collector current and −140 V collector-emitter breakdown voltage, with V_CE(sat) = −110 mV at I_C = −3 A / I_B = −300 mA, used in high-efficiency linear regulators and industrial DC-DC converter output stages.

For engineers reviewing the FZT955TA datasheet, FZT955TA pinout, FZT955TA application, or FZT955TA equivalent, key selection criteria include guaranteed h_FE ≥ 75 at I_C = −3 A, low V_CE(sat) across temperature, safe operating area up to 1 ms at −50 V/−1 A, and complementary pairing with FZT855 for push-pull switching.

Technical Context

This PNP transistor operates in active and saturation regions with specified h_FE of 100–300 (I_C = −10 mA to −10 A) and f_T = 110 MHz at I_C = −100 mA, enabling use in medium-frequency switching and analog amplification. Its V_(BR)CEO = −140 V and V_(BR)CBO = −180 V support high-voltage rail applications.

The device features low thermal resistance due to SOT-223's exposed emitter pad, delivering 3 W power dissipation on 4 in² PCB copper, with guaranteed performance from −55°C to +150°C junction temperature and V_BE(sat) = −1110 mV at I_C = −3 A.

Key Specifications

Pinout & Package

SOT-223 package with exposed emitter pad for thermal enhancement and mechanical anchoring; standardized 4-pin footprint (pin 1: Base, pin 2: Collector, pin 3: Emitter, pin 4: Emitter tab).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar PNP high-current switching applications.

Compared with ZXTN25050DFH and MJD2955G, FZT955TA uniquely balances SOT-223 mountability, −4 A current, −140 V rating, and 110 MHz f_T, making it optimal for modern space-constrained, medium-frequency power stages.

Availability

FZT955TA is available at Aetrix Electronics and suitable for industrial linear regulators, DC-DC converter output stages, and high-voltage switching applications requiring stable component supply and traceable sourcing.

Supply support for FZT955TA 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 company specializing in discrete, analog, and mixed-signal devices for power management, signal integrity, and connectivity.

FZT955TA belongs to the FZT high-performance bipolar transistor product line, engineered for high-current, high-voltage linear and switching applications in industrial and automotive power systems.

FAQ

What is the maximum safe continuous collector current for FZT955TA?

The absolute maximum continuous collector current is −4 A at T_amb = 25°C with 4 in² PCB copper. Derating is required above 25°C ambient: linear drop to zero at +150°C junction temperature. At +100°C ambient, max continuous I_C is approximately −2.8 A per thermal resistance data in the datasheet.

Does FZT955TA require a base resistor, and how is it calculated?

Yes - a base resistor is mandatory to limit I_B and ensure saturation. For −3 A collector current with h_FE = 75, minimum I_B = −40 mA. With V_BE(on) ≈ −950 mV and 3.3 V logic drive, R_B = (3.3 V − 0.95 V) / 0.04 A = 59 Ω; 56 Ω standard value is recommended.

Can FZT955TA be used in parallel for higher current?

No - inherent negative temperature coefficient of V_CE(sat) causes current hogging. Even with matched h_FE, thermal runaway occurs above 1.5 A per device without individual emitter resistors (≥0.1 Ω) and tight thermal coupling, which defeats the purpose of paralleling in SOT-223.

Is FZT955TA RoHS compliant and halogen-free?

Yes - FZT955TA is RoHS 2011/65/EU compliant and certified halogen-free per IEC 61249-2-21. The "TA" suffix denotes lead-free, green-compliant packaging with matte tin plating on SOT-223 leads and compliant molding compound.