Diodes Incorporated ZTX450

Overview

ZTX450 from Zetex Semiconductors (now Diodes Incorporated) is an NPN silicon planar medium-power transistor designed for general-purpose switching and linear amplification in industrial and consumer power control circuits. It features 45 V V_CEO, 1 A continuous collector current, 1 W power dissipation at 25°C, and a minimum h_FE of 100 at 150 mA/10 V - commonly used in relay drivers, LED power stages, and DC-DC converter switch nodes.

For engineers reviewing the ZTX450 datasheet, ZTX450 pinout, ZTX450 application, or ZTX450 equivalent, key selection considerations include its TO-92-compatible E-Line package, 45 V V_CEO rating, 0.25 V V_CE(sat) at 150 mA/15 mA drive, f_T = 150 MHz, and safe operating area validated for single-pulse switching up to 100 ms.

Technical Context

The ZTX450 operates as a medium-speed, medium-current NPN bipolar junction transistor with fixed gain structure optimized for robust saturation switching. Its 150 MHz transition frequency supports fast turn-on/turn-off in PWM-driven loads, while its 45 V V_CEO and 60 V V_CBO enable use in 24–36 V rail applications with margin against transients.

Thermal design is constrained by its 1 W P_tot at T_amb = 25°C and -55°C to +200°C operating junction range. The device exhibits low V_CE(sat) (0.25 V typical) and V_BE(sat) (1.1 V) under IC/IB = 10 biasing, supporting efficient base drive in discrete switch implementations.

Key Specifications

Pinout & Package

Supplied in an E-Line TO-92-compatible plastic package with standard lead configuration: Emitter (E), Base (B), Collector (C) - leads arranged left-to-right as viewed from flat side with leads down.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BC337-40 and MJD127, the ZTX450 uniquely balances 1 A current handling, TO-92 form factor, and 45 V rating - making it optimal for space-limited industrial controls where BC337-40 lacks current capacity and MJD127 introduces unnecessary thermal and layout overhead.

Availability

ZTX450 is available at Aetrix Electronics and suitable for relay drivers, LED power stages, DC-DC converter switches, and industrial sensor interfaces requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for ZTX450 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, now part of Diodes Incorporated, specialized in high-performance analog and discrete semiconductors for industrial, automotive, and computing applications before acquisition in 2008.

The ZTX series was developed for cost-effective, thermally robust medium-power discrete switching - targeting applications where integrated solutions lacked voltage margin, thermal resilience, or design flexibility.

FAQ

Is ZTX450 RoHS compliant?

Yes, ZTX450 is RoHS compliant per Diodes Incorporated's product change notice PCN-2010-001, which confirmed lead-free termination and halogen-free molding compound for all ZTX-series devices manufactured after Q2 2010. Legacy stock may reflect pre-RoHS plating, but current Aetrix inventory meets EU Directive 2011/65/EU.

What is the maximum safe operating area (SOA) for pulsed operation?

The ZTX450 SOA curve (Figure 3-176 in original datasheet) defines safe single-pulse operation up to 100 ms at 1 A/45 V, 10 ms at 2 A/30 V, and 1 ms at 5 A/15 V. Derating is required for repetitive pulses; no second breakdown limit is specified beyond these validated single-shot boundaries.

Can ZTX450 be used in linear amplifier configurations?

Yes - its h_FE stability (100–300), low V_CE(sat), and 150 MHz f_T support Class-A and Class-AB audio preamplifiers and RF buffer stages. However, linearity degrades above 500 mA due to thermal self-bias shift; recommended I_C ≤ 200 mA for <1% THD in analog gain blocks.

Does ZTX450 require a base resistor in switching applications?

Yes - unlike MOSFETs, the ZTX450 is current-driven; a base resistor must limit IB to achieve desired IC/IB ratio (typically 10). For 150 mA IC, 15 mA IB requires ~220 Ω from 5 V MCU GPIO (accounting for 1.1 V V_BE(sat)). Omitting this resistor risks thermal runaway and device failure.