Diodes Incorporated ZXTN04120HFFTA

Overview

ZXTN04120HFFTA from Diodes Incorporated is a 120V NPN medium-power Darlington transistor in SOT23F package, delivering 1A continuous collector current, V_CE(SAT) < 1.5V at 1A, R_CE(SAT) = 38 mΩ, and 1.5W power dissipation. It serves as a high-voltage switching element in lamp, relay, and solenoid drive circuits where space-constrained PCB layouts demand compact high-breakdown devices.

For engineers reviewing the ZXTN04120HFFTA datasheet, ZXTN04120HFFTA pinout, ZXTN04120HFFTA application, or ZXTN04120HFFTA equivalent, key selection criteria include verified 120V V_CEO, AEC-Q101 qualification for automotive reliability, thermal resistance (R_θJA = 60°C/W with 50mm × 50mm 2oz copper), and complementary PNP pairing with ZXTP05120FF.

Technical Context

This Darlington transistor integrates two cascaded NPN stages to achieve high DC current gain (h_FE ≥ 3000 at I_C = 50mA) while maintaining low saturation voltage under high-current switching. Its 140V V_CBO and 10V V_EBO support robust blocking capability across emitter-base and collector-base junctions.

The device operates over –55°C to +150°C and features ESD ratings of 2kV HBM and 200V MM. Thermal performance is defined across four mounting conditions - including 60°C/W R_θJA when mounted on 50mm × 50mm 2oz copper - enabling precise thermal design in industrial and automotive environments.

Key Specifications

Pinout & Package

Package: SOT23F - flat-lead, surface-mount plastic package with exposed collector pad; UL 94V-0 rated, moisture sensitivity level 1, weight ≈ 0.012 g.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ZXTP05120FF and MJD122G, ZXTN04120HFFTA uniquely combines AEC-Q101 qualification, SOT23F miniaturization, 120V blocking, and halogen-free construction - making it the sole option for space-limited automotive or industrial switching where reliability and regulatory compliance are mandatory.

Availability

ZXTN04120HFFTA is available at Aetrix Electronics and suitable for lamp driver, relay driver, solenoid driver, and industrial PLC output applications requiring stable component supply, automotive-grade reliability, and RoHS-compliant manufacturing.

Supply support for ZXTN04120HFFTA 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, manufacturing, and sales operations across Asia, Europe, and North America.

The ZXTN series targets high-reliability medium-power discrete switching, specifically engineered for automotive body electronics, industrial controls, and appliance motor drives demanding AEC-Q101 validation and compact thermal packaging.

FAQ

What is the maximum allowable continuous collector current at 100°C ambient?

At T_A = 100°C, the device's thermal derating limits continuous I_C to approximately 0.65A. This is calculated using the 12.0 mW/°C linear derating factor from the 1.5W rating at 25°C, resulting in 1.5W − (75°C × 12 mW/°C) = 0.6W max dissipation, yielding ~0.65A at V_CE(SAT) ≈ 0.9V.

Can ZXTN04120HFFTA replace a standard NPN transistor like BC817 in a 24V relay driver?

Yes - with design adjustments. Its higher V_CEO (120V vs. 45V) and lower V_CE(SAT) improve transient immunity and efficiency, but its Darlington architecture requires ~10× less base current and exhibits slower switching (t_S = 910 ns). Base resistor values must be increased, and snubber networks may be needed for fast turn-off.

Is the exposed collector pad electrically isolated from other pins?

No - the exposed collector pad is electrically connected to Pin 3 (collector) and forms the primary current and thermal path. It must be soldered to a dedicated copper pour tied to the collector net; isolation would compromise both electrical function and thermal performance.

Does ZXTN04120HFFTA support pulsed operation beyond 1A?

Yes - the datasheet specifies I_CM = 4A peak pulse current with ≤2% duty cycle and ≤300µs pulse width. This enables short-duration surge handling (e.g., solenoid pull-in) but requires strict adherence to pulse conditions to avoid second breakdown or thermal runaway.