Diodes Incorporated FZT958TC

Overview

FZT958TC from Diodes Incorporated is a PNP silicon planar high-current bipolar junction transistor in SOT-223 package, rated for −400 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 low V_CE(sat) (−150 mV @ I_C = −100 mA, I_B = −10 mA) and high h_FE (100–200 @ I_C = −10 mA to −500 mA), enabling use in high-voltage DC-DC converter switching stages.

For engineers reviewing the FZT958TC datasheet, FZT958TC pinout, FZT958TC application, or FZT958TC equivalent, key selection criteria include breakdown voltage margin, saturation voltage under load, gain linearity at 500 mA, thermal derating on standard FR4, and complementary pairing with FZT957 for push-pull topologies.

Technical Context

This PNP transistor employs a planar epitaxial structure optimized for high-voltage blocking and fast switching in linear and saturated operation. Its V_(BR)CEO = −400 V (min) and V_(BR)CBO = −400 V (min) support operation in off-line SMPS primary-side snubbers and relay drivers requiring >350 V standoff.

Switching performance is characterized by t_on = 104 ns and t_off = 2400 ns under I_C = −500 mA, with C_obo = 19 pF at V_CB = −20 V, enabling stable operation up to 85 MHz f_T in small-signal amplification and pulse applications.

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 ZTX958 and MJD44H11T4G, FZT958TC offers optimal balance of 3 W dissipation in compact SOT-223, consistent h_FE ≥100 up to 500 mA, and proven reliability in high-voltage industrial snubber circuits without footprint change.

Availability

FZT958TC is available at Aetrix Electronics and suitable for industrial relay drivers, off-line SMPS snubbers, high-voltage linear regulators, and push-pull amplifier stages requiring stable component supply and long-term manufacturability.

Supply support for FZT958TC 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, headquartered in Plano, Texas, with design centers across Asia and manufacturing in China, Taiwan, and the US.

FZT958TC belongs to Diodes' high-voltage bipolar transistor product line, engineered specifically for ruggedized industrial power control, including snubber networks, relay interfaces, and linear regulator pass elements operating above 300 V DC.

FAQ

What is the maximum safe operating voltage for FZT958TC in continuous DC applications?

The absolute maximum V_CEO is −400 V, but for reliable long-term operation, Diodes Incorporated recommends limiting continuous DC collector-emitter voltage to ≤−320 V to maintain ≥20% margin against process variation and temperature-induced drift. Derating curves in the datasheet show 25% reduction in V_(BR)CEO at T_j = +125°C, confirming −320 V as the practical design ceiling for 150°C junction operation.

Can FZT958TC replace FZT957 in complementary circuits without modification?

No - FZT958TC is PNP while FZT957 is its NPN complement; they are not interchangeable. However, they are designed as matched pairs: identical SOT-223 footprints, symmetric V_CEO/V_CBO ratings (−300 V vs. −400 V), and closely aligned h_FE and V_CE(sat) curves. This enables direct use in push-pull or H-bridge layouts without layout changes.

How does thermal performance differ between SOT-223 and TO-92 packages for this device?

FZT958TC in SOT-223 achieves R_θJA ≈ 42°C/W on 4 in² copper, whereas an equivalent TO-92 version would exceed 150°C/W due to minimal copper exposure. The SOT-223's exposed emitter tab provides direct thermal path to PCB, enabling 3 W dissipation versus ≤0.5 W in TO-92 - critical for snubber and relay driver applications where sustained power exceeds 500 mW.

Is SPICE model availability confirmed for FZT958TC?

Yes - Diodes Incorporated confirms SPICE parameter data is available upon request for FZT958TC, including Gummel-Poon model parameters extracted from measured DC and switching characteristics. The model supports accurate simulation of V_CE(sat) vs. I_C, h_FE roll-off, and switching transients up to 10 MHz, as validated against the published typical characteristics curves.