Diodes Incorporated FZT849TC

Overview

FZT849 from Diodes Incorporated is a 30V NPN medium-power high-current transistor in SOT223 package, rated for 7A continuous collector current, 20A peak pulse current, and 3W power dissipation, with V_CE(SAT) = 35 mV (typ.) at I_C = 500 mA / I_B = 20 mA, used in DC-DC converter switching stages and motor driver output stages.

For engineers reviewing the FZT849 datasheet, FZT849 pinout, FZT849 application, or FZT849 equivalent, key selection criteria include verified V_CE(SAT) at high I_C, thermal resistance R_θJA = 42 °C/W (52 mm × 52 mm 2 oz Cu), AEC-Q101 qualification, and complementary PNP pairing with FZT949.

Technical Context

This NPN bipolar junction transistor operates in linear and saturated switching modes, supporting high-current DC loads with low saturation voltage and fast switching (t_ON = 45 ns, t_OFF = 630 ns). Its BV_CEO = 30 V and I_C = 7 A rating enable use in 24V industrial power rails.

The device features a thermally optimized SOT223 package with exposed collector tab for direct PCB copper thermal coupling, and exhibits h_FE = 100 (min) at I_C = 10 mA and h_FE = 30 (min) at I_C = 7 A - confirming stable gain across operating range.

Key Specifications

Pinout & Package

SOT223 package with three terminals: emitter (E), base (B), and collector (C); collector connected to large exposed metal tab for thermal and electrical connection to PCB copper pour.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ZXTN25040DFH and MJD122, FZT849 uniquely balances 7A current, 30V rating, SOT223 compactness, and AEC-Q101 compliance - making it optimal for space-constrained automotive and industrial switching where thermal design follows Diodes' 52 mm² copper guideline.

Availability

FZT849 is available at Aetrix Electronics and suitable for DC-DC converters, motor drivers, automotive lamp controls, and industrial solenoid interfaces requiring stable component supply and AEC-Q101 assurance.

Supply support for FZT849 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 U.S.

FZT849 belongs to Diodes' high-reliability power transistor product line, engineered specifically for automotive and industrial switching applications demanding AEC-Q101 qualification, low saturation voltage, and robust thermal performance in surface-mount packages.

FAQ

What is the maximum allowable junction temperature for FZT849?

The FZT849 has an operating junction temperature range of –55°C to +150°C. Its absolute maximum T_J is +150°C; sustained operation above this threshold risks permanent degradation. Derating begins at T_A = 25°C using R_θJA = 42 °C/W (52 mm × 52 mm 2 oz Cu), so at T_A = 85°C, max usable P_D drops to ~1.7 W.

Is FZT849 pin-compatible with FZT949?

No - FZT849 (NPN) and FZT949 (PNP) share identical SOT223 mechanical packaging and pinout order (E-B-C), but their polarity and biasing requirements differ fundamentally. They are complementary devices intended for push-pull or H-bridge configurations, not direct replacements.

Does FZT849 require a heatsink in standard PCB layouts?

When mounted per Diodes' recommended layout (52 mm × 52 mm 2 oz Cu), the FZT849 achieves R_θJA = 42 °C/W and can dissipate its full 3W rating at T_A = 25°C without an external heatsink. Smaller copper areas increase R_θJA significantly - e.g., 25 mm × 25 mm 1 oz Cu yields R_θJA = 78 °C/W, limiting P_D to ~1.6 W at 25°C ambient.

What is the guaranteed h_FE at I_C = 7 A and V_CE = 1 V?

Per DS33173 Rev. 5-2, h_FE is guaranteed ≥30 at I_C = 7 A and V_CE = 1 V. This minimum gain ensures predictable base current requirements (I_B ≤ 233 mA) for full saturation, enabling accurate driver stage design without over-specifying base drive capability.