Diodes Incorporated FZT957QTC

Overview

FZT957QTC from Diodes Incorporated is a 300V PNP high-voltage transistor in SOT223 package, designed for high-voltage switching and linear regulation. It delivers -1A continuous collector current, -300V V_CEO, and V_CE(sat) < -240mV @ -1A, enabling robust operation in off-line power supplies and industrial control circuits.

For engineers reviewing the FZT957QTC datasheet, FZT957QTC pinout, FZT957QTC application, or FZT957QTC equivalent, key selection criteria include high-voltage blocking capability, low saturation voltage under high current, thermal performance on 52mm×52mm 2oz copper PCBs, and complementary pairing with FZT857 for push-pull topologies.

Technical Context

This PNP bipolar junction transistor operates with a minimum BV_CEO of -300V and supports peak pulse current up to -2A. Its h_FE remains ≥90 at -1A and ≥10 at -2A, ensuring stable gain across load range. The device is rated for operation from -55°C to +150°C with JEDEC Class 3A HBM ESD rating (4kV).

Thermal resistance is specified as R_θJA = 42°C/W on 52mm×52mm 2oz copper, and R_θJL = 8.8°C/W to lead-critical for heatsinkless designs requiring direct lead soldering. Switching times are t_on = 108ns and t_off = 2.5μs under -100V V_CC, -500mA I_C, and ±50mA base drive.

Key Specifications

Pinout & Package

Package: SOT223 (Type DN), surface-mount, 4-pin configuration with exposed collector tab (pin 3) for thermal conduction. Molded green compound, RoHS-compliant, matte tin-plated leads.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar PNP high-voltage transistor applications.

Compared with NSS12201CF and STN93020, FZT957QTC uniquely combines -300V blocking, -1A continuous current, and sub-240mV saturation in SOT223-enabling single-device solutions in off-line power, high-voltage braking, and industrial actuation where both voltage headroom and thermal efficiency are critical.

Availability

FZT957QTC is available at Aetrix Electronics and suitable for industrial relay drivers, off-line flyback snubbers, and DC motor brake circuits requiring stable component supply and long-term manufacturability.

Supply support for FZT957QTC 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 integrated circuits, specializing in high-reliability power management, signal integrity, and protection devices.

FZT957QTC belongs to Diodes' high-voltage bipolar transistor product line, engineered for ruggedized industrial and automotive power control applications demanding extended voltage range and thermal resilience.

FAQ

What is the maximum safe operating voltage for FZT957QTC in continuous DC mode?

The absolute maximum collector-emitter voltage (V_CEO) is -300V at T_A = +25°C. Derating is required above 25°C: voltage rating decreases linearly by 0.25V/°C above 25°C per the datasheet's safe operating area curve. At 100°C ambient, the practical limit is approximately -281V for DC operation with adequate heatsinking.

Can FZT957QTC be used as a direct replacement for FZT957TA or FZT957TC?

Yes-FZT957QTC shares identical electrical specifications, SOT223 (Type DN) package, and marking code (FZT957) with FZT957TA and FZT957TC. The "Q" suffix denotes qualification to AEC-Q101, but all three variants are pin- and electrically compatible. Reel size and tape width differ (13-inch reel, 12mm tape, 4,000 units), but no design changes are needed.

How should the exposed collector tab be connected on the PCB for optimal thermal performance?

The exposed collector tab (Pin 3 and Pin 4) must be soldered to a minimum 52mm × 52mm area of 2oz copper on the PCB to achieve the rated R_θJA = 42°C/W. Thermal vias under the tab are recommended, and the copper pour must remain unbroken and directly connected to the collector net-no isolation gaps or thermal relief spokes.

Is FZT957QTC suitable for automotive applications?

The FZT957Q variant-not FZT957QTC-is the AEC-Q101 qualified version intended for automotive use. While FZT957QTC shares identical electrical and mechanical characteristics, it lacks the extended temperature cycling, humidity testing, and failure analysis documentation required for automotive qualification. Use FZT957Q for under-hood or safety-critical vehicle systems.