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Home > Products > Discrete Semiconductor Products > Transistors > Bipolar (BJT) > Single Bipolar Transistors

Diodes Incorporated FZT957TA

Name: FZT957TA
Brand: Diodes Incorporated
SKU: FZT957TA
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: FZT957TA

Manufacturer:: Diodes Incorporated

Category:: Single Bipolar Transistors

Package:: TO-261-4, TO-261AA

Datasheet:: FZT957TA.pdf

Description:: TRANS PNP 300V 1A SOT-223-3

Quantity:: RFQ Add To RFQ list

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Inventory:3,383

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Product details

Overview

FZT957TA from Diodes Incorporated is a PNP silicon planar high-current bipolar junction transistor in SOT-223 package, rated for −300 V V_CEO, −1 A continuous collector current, and 3 W power dissipation at T_amb = 25°C with ≥4 in² PCB copper. It delivers V_CE(sat) = −170 mV at I_C = −1 A / I_B = −300 mA and h_FE = 90–170 across 10 mA–1 A, used in high-voltage DC-DC converter switching stages and industrial relay drivers.

For engineers reviewing the FZT957TA datasheet, FZT957TA pinout, FZT957TA application, or FZT957TA equivalent, key selection criteria include verified V_CEO rating, low saturation voltage under high I_C, gain stability up to 1 A, thermal performance on standard PCB layout, and complementary pairing with FZT857 for push-pull topologies.

Technical Context

This PNP BJT operates in linear or saturated switching mode with base-controlled current amplification. Its design supports high-voltage off-state blocking (−300 V V_CEO) and robust pulsed conduction (−2 A I_CM), validated under ≤2% duty cycle, 300 µs pulse width conditions.

Gain behavior is characterized across temperature (−55°C to +150°C) and collector current (10 mA–2 A) with fixed V_CE = −10 V and multiple I_C/I_B ratios; f_T = 85 MHz at I_C = −100 mA confirms suitability for medium-frequency switching applications up to several MHz.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	−300 V - Maximum sustainable collector-emitter voltage before breakdown in open-base configuration.
I_C (cont.)	−1 A - Continuous DC collector current rating with 3 W dissipation on 4 in² PCB copper at 25°C ambient.
V_CE(sat)	−170 mV @ I_C = −1 A, I_B = −300 mA - Low on-state loss enabling <0.17 W conduction loss in high-current switches.
h_FE	90–170 @ I_C = −1 A, V_CE = −10 V - Stable DC current gain supporting predictable base drive sizing.
f_T	85 MHz @ I_C = −100 mA, V_CE = −10 V - Enables use in <10 MHz switching converters without significant gain roll-off.
T_j Range	−55°C to +150°C - Qualified for industrial and extended-temperature embedded power control environments.

Pinout & Package

SOT-223 package with exposed emitter pad for thermal enhancement; standard 4-pin outline (3 active + 1 thermal tab), mounted via soldered tab to ≥4 in² copper area for rated 3 W dissipation.

Pin/Terminal	Circuit Role	Design Meaning
1 (Emitter)	Main current return path	Connected to PCB ground plane or low-impedance return; tab is electrically tied to emitter and provides primary thermal conduction path.
2 (Base)	Current-controlled input	Receives negative bias current to turn on PNP; requires external current-limiting resistor for safe drive.
3 (Collector)	High-voltage switched output	Handles −300 V potential and −1 A load current; routed away from sensitive nodes due to high dV/dt during switching.
4 (Emitter Tab)	Thermal & electrical common	Not electrically isolated; must be soldered to large copper pour for thermal management and low-inductance emitter return.

Key Features

Feature	Design Value
High-voltage blocking	−300 V V_CEO enables direct interface with 240 VAC-derived rails or flyback snubber networks.
Low saturation loss	V_CE(sat) ≤ −170 mV at full 1 A load reduces conduction heating and improves efficiency in linear regulators or switch-mode drivers.
Gain stability at high current	h_FE ≥ 90 maintained up to I_C = −1 A ensures reliable base drive margin without overdesign.
Thermally optimized package	SOT-223 emitter tab allows 3 W dissipation on standard FR4 with minimal heatsinking-no TO-220 footprint required.

Applications

Industrial Relay Drivers

High-Voltage DC-DC Converters

Use Scenario: Driving 24–48 VDC coils of industrial electromechanical relays in PLC I/O modules.

IC Role / Device Role / Timing Role: High-side PNP switch controlling coil current path to ground; handles repetitive 1 A inductive turn-off spikes.

Use Value: −300 V V_CEO withstands >200 V inductive kickback; low V_CE(sat) minimizes self-heating during sustained actuation.

Use Scenario: Primary-side switching element in isolated flyback or forward converters operating from 100–400 VDC bus.

IC Role / Device Role / Timing Role: Main power switch in non-synchronous topology; gated at 50–500 kHz with controlled rise/fall times.

Use Value: 85 MHz f_T and fast 108 ns t_on support efficient medium-frequency operation; SOA curve validated for single-pulse 100 V/1 A stress.

Linear Regulator Pass Transistors

High-Voltage LED String Drivers

Use Scenario: Series pass element in adjustable high-voltage linear regulators delivering up to 100 mA at 100–300 V output.

IC Role / Device Role / Timing Role: Voltage-controlled current source operating in active region; dissipates up to 2.5 W continuously.

Use Value: h_FE consistency across temperature ensures stable loop gain; 150°C max T_j allows compact thermal design.

Use Scenario: Constant-current sink for 50–100 V LED strings in signage or architectural lighting.

IC Role / Device Role / Timing Role: Precision current regulator using emitter degeneration resistor; biased in linear mode with feedback.

Use Value: Low V_BE(sat) (−910 mV) and tight h_FE tolerance enable accurate current setting without trimming.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
ZTX957	V_CEO = −300 V, I_C = −1 A, but V_CE(sat) = −200 mV @ −1 A - 30 mV higher saturation loss.	Same SOT-223 footprint; lower gain uniformity (h_FE = 50–150) increases base drive uncertainty.	Acceptable where thermal margin exists; avoid in thermally constrained 1 A continuous designs.
MJD2955G	V_CEO = −60 V only; I_C = −10 A - trades voltage rating for current capacity and TO-220 thermal mass.	Requires heatsink and larger board area; unsuitable for >100 V applications due to voltage limitation.	Only viable in low-voltage, high-current scenarios; not a functional substitute for −300 V operation.

Compared with ZTX957 and MJD2955G, FZT957TA uniquely balances −300 V blocking, −1 A current, low −170 mV saturation, and SOT-223 thermal efficiency-making it optimal for space-constrained, high-voltage industrial switching where alternatives compromise either voltage rating, loss, or form factor.

Availability

FZT957TA is available at Aetrix Electronics and suitable for industrial relay drivers, high-voltage DC-DC converters, linear regulator pass elements, and LED string current sinks requiring stable component supply across extended temperature and high-reliability production cycles.

Supply support for FZT957TA 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, computing, and consumer markets.

FZT957TA belongs to Diodes' high-voltage bipolar transistor product line, engineered specifically for ruggedized switching and linear regulation in 100–400 V systems where thermal efficiency and voltage margin are critical.

FAQ

What is the maximum allowable case temperature for continuous operation?

The FZT957TA has a maximum junction temperature of +150°C and is rated for 3 W dissipation at T_amb = 25°C with ≥4 in² PCB copper. Under typical mounting, case temperature should not exceed +125°C to maintain 25°C safety margin; derating is linear at 24 mW/°C above 25°C ambient.

Can FZT957TA be used in avalanche mode?

No-FZT957TA is not rated or characterized for controlled avalanche operation. Its V_(BR)CEO = −300 V is a DC breakdown limit; repetitive avalanche stress may cause parametric shift or failure. Use external clamping (e.g., TVS diode) for inductive load protection.

Is the SOT-223 emitter tab electrically isolated?

No-the emitter tab in the SOT-223 package is internally bonded to the emitter terminal and is not insulated. It must be soldered to a PCB copper area designated as the emitter node; isolation requires external insulation or mechanical standoff, which voids thermal rating.

How does gain variation affect base drive design at 1 A load?

With h_FE = 90–170 at I_C = −1 A, base current must be designed for worst-case 90 gain: I_B = −1 A / 90 ≈ −11.1 mA. A −300 mA drive (per datasheet test condition) provides >26× overdrive, ensuring hard saturation and minimizing V_CE(sat) spread across unit-to-unit and temperature.

FZT957TA Specifications

Product attributes: Attribute value

Manufacturer:: Diodes Incorporated

Series:: -

Package/Case:: TO-261-4, TO-261AA

Packaging:: Tape & Reel (TR)

Product Status:: Active

Transistor Type:: PNP

Current - Collector (Ic) (Max):: 1 A

Voltage - Collector Emitter Breakdown (Max):: 300 V

Vce Saturation (Max) @ Ib, Ic:: 240mV @ 300mA, 1A

Current - Collector Cutoff (Max):: 50nA (ICBO)

DC Current Gain (hFE) (Min) @ Ic, Vce:: 100 @ 500mA, 10V

Power - Max:: 3 W

Frequency - Transition:: 85MHz

Operating Temperature:: -55°C ~ 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: SOT-223-3

FZT957TA FAQ

1.How can I place an order for FZT957TA through Aetrix?

Please submit a Request for Quotation (RFQ) for FZT957TA on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for FZT957TA reliable?

The price and inventory of FZT957TA are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for FZT957TA is usually 5 days.

3.What payment methods are accepted for FZT957TA?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for FZT957TA transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for FZT957TA?

FZT957TA orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your FZT957TA order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for FZT957TA?

For technical support, including FZT957TA datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your FZT957TA requirements.

6.How does Aetrix verify that FZT957TA is sourced from the original manufacturer or authorized distributors?

All FZT957TA products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that FZT957TA meets industry standards.

7.What is the process for return or replacement of FZT957TA?

All FZT957TA units undergo pre-shipment inspection (PSI). If there is an issue with FZT957TA, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The FZT957TA part is unused and in its original packaging.

Return procedure for FZT957TA:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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