Diodes Incorporated FMMT497TC

Overview

FMMT497TC from Zetex Semiconductors is an NPN silicon planar high-voltage transistor in SOT-23 package, rated for 300 V V_CEO, 500 mA I_C, and 75 MHz f_T, designed for high-voltage switching in industrial power supplies and flyback converters.

For engineers reviewing the FMMT497TC datasheet, FMMT497TC pinout, FMMT497TC application, or FMMT497TC equivalent, key selection criteria include safe operating area at 100 V, low V_CE(sat) of 0.2 V at 100 mA/10 mA drive, and robust 300 V breakdown ratings under pulsed and DC conditions.

Technical Context

This high-voltage NPN transistor features a planar silicon structure optimized for fast switching with t_d = 53 ns, t_r = 126 ns, and t_f = 228 ns under 100 V/100 mA conditions. Its h_FE ranges from 20 to 300 across 1 mA–250 mA collector current, supporting both linear amplification and saturated switching modes.

The device operates across –55 °C to +150 °C junction temperature, with guaranteed V_(BR)CEO(sus) = 300 V (pulsed, 300 µs, 2% duty), and exhibits low leakage: I_CBO ≤ 100 nA at V_CB = 250 V, enabling stable performance in high-impedance bias networks.

Key Specifications

Pinout & Package

Package: SOT-23 - Surface-mount plastic package with gull-wing leads, 1.4 mm × 2.64 mm footprint, 1.12 mm height, optimized for automated assembly and thermal performance in compact power stages.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ZTX450 and FMMT618, FMMT497TC uniquely balances 300 V capability, SOT-23 form factor, and 75 MHz bandwidth-making it optimal for space-constrained, high-input-voltage flyback and auxiliary supply designs where thermal and layout constraints preclude larger packages or lower-voltage alternatives.

Availability

FMMT497TC is available at Aetrix Electronics and suitable for industrial power supplies, flyback converters, DC motor drivers, and high-voltage logic interfaces requiring stable component supply and long-term production continuity.

Supply support for FMMT497TC 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

Zetex Semiconductors plc was a UK-based ISO 9001 and TS16949-certified designer and manufacturer of high-performance analog and discrete semiconductors, acquired by Diodes Incorporated in 2008.

FMMT497TC belongs to Zetex's high-voltage bipolar transistor product line, engineered specifically for reliable switching in offline AC/DC power conversion and industrial control systems operating up to 300 V.

FAQ

What is the maximum allowable base current for continuous operation?

The absolute maximum continuous base current is 200 mA per the datasheet's Absolute Maximum Ratings table. However, for reliable long-term operation at 500 mA collector current, base drive should be limited to ≤25 mA (I_B/I_C = 0.05) to avoid excessive base-emitter junction heating and maintain h_FE stability across temperature.

Can FMMT497TC replace a BC337 in a 24 V circuit?

Yes, but only if the application does not require its full 300 V rating. The FMMT497TC has higher V_CEO, higher f_T, and lower V_CE(sat) than BC337, but its h_FE minimum is lower (20 vs. 100). Circuit redesign may be needed to ensure sufficient base drive and verify gain-dependent loop stability in linear applications.

Is FMMT497TC RoHS compliant?

Yes. Per Zetex's 2006 datasheet and corporate environmental policy, FMMT497TC is RoHS-compliant and supports customer compliance with WEEE and ELV directives. It contains no lead, mercury, cadmium, hexavalent chromium, PBB, or PBDE above threshold limits.

Does the device have built-in ESD protection?

No. The datasheet does not specify on-chip ESD protection structures. As noted in the "ESD (Electrostatic discharge)" section, FMMT497TC is susceptible to ESD damage, and users must implement handling precautions including grounded workstations, ionizers, and conductive packaging during assembly and test.