Diodes Incorporated FZT957TC

Overview

FZT957TC 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 = 90–300 across I_C = −10 mA to −1 A, used in high-voltage linear regulators and industrial switching supplies.

For engineers reviewing the FZT957TC datasheet, FZT957TC pinout, FZT957TC application, or FZT957TC equivalent, key selection criteria include verified V_CEO rating, saturation voltage under high I_C, thermal performance on standard PCB layout, and complementary NPN pairing with FZT857 for push-pull stages.

Technical Context

This PNP BJT operates in active and saturation regions with specified h_FE down to I_C = −2 A (min 10) and V_CE(sat) characterized up to −1 A. Its low V_CE(sat) and high V_CEO support efficient high-voltage switching in offline power converters and relay drivers.

The device features f_T = 85 MHz at I_C = −100 mA / V_CE = −10 V and C_obo = 23 pF at V_CB = −20 V, enabling use in medium-frequency switching applications where gain-bandwidth trade-offs must be validated against load dynamics.

Key Specifications

Pinout & Package

SOT-223 package with exposed emitter pad for thermal enhancement and mechanical stability; standardized 4-pin footprint (3 active + 1 thermal tab), JEDEC TO-261AA compliant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ZTX953 and MJD2955G, FZT957TC uniquely balances −300 V capability, SOT-223 compactness, and −170 mV saturation in a single-source solution for space-constrained industrial HV switching.

Availability

FZT957TC is available at Aetrix Electronics and suitable for industrial power supplies, high-voltage linear regulators, relay drivers, and push-pull output stages requiring stable component supply across extended temperature and voltage ranges.

Supply support for FZT957TC 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 industrial, computing, consumer, and communications markets.

FZT957TC belongs to the FZT high-voltage bipolar transistor product line, engineered for robust high-voltage switching and regulation in space-constrained industrial power systems.

FAQ

What is the maximum safe operating voltage for FZT957TC in continuous DC applications?

The absolute maximum V_CEO is −300 V, but for reliable long-term operation, design to ≤80% of rating (−240 V) with appropriate derating for temperature and transients. The device's V_(BR)CEO is −300 V at I_C = −10 mA, confirmed per datasheet Figure 3-291, and its SOA curve supports 100 V at 1 A DC with 4 in² copper.

Can FZT957TC replace FZT653 in an existing design?

Yes, with validation: FZT957TC offers −300 V V_CEO vs. FZT653's −100 V, −170 mV V_CE(sat) vs. −400 mV, and higher h_FE (90–300 vs. 25–200). Base resistor values may require reduction due to lower V_BE(sat) (−910 mV), and PCB copper area must meet 4 in² minimum for thermal compliance.

Is the SOT-223 thermal tab electrically isolated?

No - the metal tab is internally connected to the emitter (Pin 1) and must be treated as a live terminal. It must be soldered directly to a grounded or emitter-referenced copper pour; isolation requires insulating thermal pads or dielectric coatings, which increase θ_JA by ≥15°C/W.

Does FZT957TC have SPICE model support?

Yes - Diodes Incorporated provides verified SPICE parameter data upon request, including Gummel-Poon model parameters extracted from measured DC and transient characteristics. The model covers V_CE(sat), h_FE, f_T, and capacitance behavior across −55°C to +150°C, usable in LTspice and PSpice simulations.