Diodes Incorporated FMMT455TC

Overview

FMMT455TC from Diodes Incorporated is a SOT-23 packaged NPN silicon planar transistor rated for 140 V V_CEO, 1 A continuous collector current, and 500 mW power dissipation; it delivers h_FE = 100–300 at I_C = 150 mA / V_CE = 10 V and f_T = 100 MHz, used in high-voltage switching and linear amplification stages of industrial power supplies.

For engineers reviewing the FMMT455TC datasheet, FMMT455TC pinout, FMMT455TC application, or FMMT455TC equivalent, key selection criteria include verified V_CEO(sus) = 140 V, guaranteed h_FE min = 100 at I_C = 150 mA, C_obo = 15 pF at V_CB = 10 V, t_f = 900 ns, and safe operating area validated to 100 µs pulse width with I_C up to 2 A.

Technical Context

This device employs a high-voltage planar epitaxial structure enabling stable operation up to T_j = +150 °C and sustaining V_CEO(sus) = 140 V under pulsed conditions (300 µs, ≤2% duty cycle). Its f_T = 100 MHz at I_C = 50 mA / V_CE = 10 V supports medium-frequency switching, while V_CE(sat) = 0.7 V at I_C = 150 mA / I_B = 15 mA ensures low conduction loss in saturated switch mode.

The SOT-23 package provides thermal resistance R_θJA ≈ 300 K/W, limiting continuous power to 500 mW at T_amb = 25 °C; its C_obo = 15 pF and low V_BE(on) support fast turn-on in driver circuits where base drive efficiency and output capacitance impact rise time.

Key Specifications

Pinout & Package

SOT-23 surface-mount plastic package with standard lead frame geometry; compact 3-pin footprint (2.9 mm × 1.3 mm × 1.0 mm) optimized for automated assembly and thermal relief on PCBs.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar NPN high-voltage switching applications.

Compared with ZTX455 and MMBT4401, FMMT455TC uniquely balances 140 V blocking, 1 A current, and 100 MHz f_T in SOT-23-making it irreplaceable in 48–100 V industrial switching where both voltage headroom and gain stability are non-negotiable.

Availability

FMMT455TC is available at Aetrix Electronics and suitable for industrial power supplies, LED drivers, automotive load switching, and analog signal amplification requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for FMMT455TC 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 manufacturer specializing in discrete, analog, and mixed-signal solutions for industrial, computing, and consumer markets.

FMMT455TC belongs to the FMMT series of high-performance SOT-23 transistors designed specifically for space-constrained, high-voltage switching and amplification in industrial power conversion and control systems.

FAQ

What is the maximum allowable junction temperature for FMMT455TC?

The absolute maximum junction temperature is +150 °C, with storage temperature matching this range. Operation above this limit risks permanent degradation of h_FE and increased leakage. Thermal design must ensure R_θJA × P_diss + 25 °C ≤ 150 °C under worst-case ambient conditions.

Does FMMT455TC support pulsed current beyond its 1 A continuous rating?

Yes-absolute maximum peak pulse current I_CM is 2 A under pulsed conditions (pulse width = 300 µs, duty cycle ≤ 2%). This enables short-duration overload handling in motor start-up or surge protection circuits without thermal runaway.

Is the FMMT455TC pinout compatible with standard SOT-23 NPN transistors?

Yes-pin 1 is Emitter, pin 2 is Base, pin 3 is Collector, conforming to JEDEC TO-236AB standard. This matches ZTX455, MMBT4401, and BC847 series, allowing drop-in replacement where voltage/current ratings permit.

What is the typical V_BE(on) at I_C = 150 mA and I_B = 15 mA?

V_BE(on) is typically 0.85 V under those conditions, per characteristic curves in the datasheet. This value determines base resistor sizing in fixed-bias configurations and impacts total drive power in high-frequency switching.