Diodes Incorporated ZUMT618TC

Overview

ZUMT618TC from Diodes Incorporated is an NPN silicon power switching transistor in SOT323 package, rated for 1.25A continuous collector current, 20V V_CEO, and 125 mΩ typical R_CE(sat) at 1.25A/50mA drive; used in corded telecoms line drivers and DC-DC boost stages.

For engineers reviewing the ZUMT618TC datasheet, ZUMT618TC pinout, ZUMT618TC application, or ZUMT618TC equivalent, key selection criteria include verified R_CE(sat) ≤155 mV at 1.25A, h_FE ≥200 at 10mA, f_T = 210 MHz, safe operating area up to 4A pulsed, and thermal performance on FR4 (385–500 mW P_tot).

Technical Context

This device operates as a medium-current, high-speed NPN switch with low saturation voltage optimized for linear and switching operation in compact power stages. Its 210 MHz f_T supports fast turn-on (50 ns) and controlled turn-off (275 ns) under pulsed 100 mA base drive.

Designed for stable gain across temperature, it delivers h_FE = 420 (typ.) at 10 mA and maintains ≥60 at 4 A, enabling robust current amplification in motor driver half-bridges and telecom line interface circuits where low V_BE(sat) (955–1100 mV) reduces base drive loss.

Key Specifications

Pinout & Package

SOT323 (SC-70) 3-pin surface-mount package: ultra-compact footprint (2.1 × 1.25 × 0.95 mm), thermally enhanced for power dissipation in space-constrained designs.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar NPN power switching transistor applications.

Compared with DXT618STQ and MMBT618LT1G, ZUMT618TC offers superior R_CE(sat) stability, higher f_T, and broader SOA-making it the optimal choice for thermally constrained, high-reliability telecom and boost converter applications demanding repeatable 1.25A switching performance.

Availability

ZUMT618TC is available at Aetrix Electronics and suitable for corded telecom line interfaces, DC-DC boost converters, brushed DC motor drivers, and LED current regulators requiring stable component supply and guaranteed parametric compliance.

Supply support for ZUMT618TC 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, specializing in high-performance, high-reliability components for power management, signal integrity, and connectivity applications.

ZUMT618TC belongs to the Super323™ family of power transistors engineered for compact, high-efficiency switching in telecom infrastructure, industrial controls, and consumer power supplies where low R_CE(sat) and fast switching are critical.

FAQ

What is the maximum safe operating temperature for ZUMT618TC?

The ZUMT618TC is rated for junction and storage temperatures from –55°C to +150°C. Its thermal resistance (R_θJA) is approximately 320°C/W on 10×8 mm FR4, so sustained operation at 1.25A requires ambient ≤75°C or board-level thermal enhancement to avoid exceeding T_j = 150°C.

Can ZUMT618TC replace a standard small-signal transistor like BC847 in a switching application?

No-ZUMT618TC is a power transistor optimized for 1.25A continuous current and low R_CE(sat); BC847 is rated for 100mA and has much higher saturation voltage. Substituting it without recalculating base drive, thermal layout, and SOA margins risks thermal runaway or premature failure.

Is ZUMT618TC RoHS compliant and halogen-free?

Yes-ZUMT618TC meets RoHS Directive 2011/65/EU and is certified halogen-free per IEC 61249-2-21. The SOT323 package uses matte tin lead finish and green molding compound, with full compliance documentation available from Diodes Incorporated's product change notices.

What is the recommended base resistor value for driving ZUMT618TC at 1.25A collector current?

To achieve I_B = 50 mA (I_C/I_B = 25) with V_BE(sat) ≈ 1.1 V and 3.3V logic drive, use R_B = (3.3 V − 1.1 V) / 0.05 A = 44 Ω. A standard 43 Ω, 1/8 W resistor provides appropriate margin while ensuring reliable saturation and avoiding excessive base current.