Diodes Incorporated ZTX458STOA

Overview

ZTX458STOA from Diodes Incorporated is an NPN silicon planar medium-power high-voltage transistor with V_CEO = 400 V, I_C = 300 mA continuous, P_tot = 1 W at T_amb = 25°C, h_FE = 100–300 (I_C = 1–100 mA), and f_T = 50 MHz - used in high-voltage switching and linear amplification stages of industrial power supplies and CRT deflection circuits.

For engineers reviewing the ZTX458STOA datasheet, ZTX458STOA pinout, ZTX458STOA application, or ZTX458STOA equivalent, key selection criteria include verified 400 V blocking capability, safe SOA under pulsed loads up to +175°C junction, and TO-92-compatible leadform compatibility with legacy E-Line board layouts.

Technical Context

This NPN bipolar junction transistor employs a planar silicon die optimized for high-voltage breakdown stability and moderate-speed switching. Its V_CEO(sus) = 400 V and V_CBO = 400 V are rated under sustained DC conditions, and its f_T = 50 MHz supports operation in line-frequency and low-MHz switching applications.

The device exhibits low V_CE(sat) = 0.2–0.5 V across I_C = 20–50 mA with base drive ratios of 10–100, and maintains h_FE ≥ 15 at I_C = 100 mA, enabling reliable current gain in saturated switch configurations.

Key Specifications

Pinout & Package

Package: TO-92 (E-Line compatible, 3-182 outline). Molded plastic case with 2.54 mm lead pitch, axial leads, and JEDEC-standard footprint.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ZTX458STOA, ZTX450 trades 100 V blocking headroom for identical package and gain, while BCV46 sacrifices both voltage and current capability for SMT compatibility - making ZTX458STOA the sole option for 400 V, 300 mA, through-hole medium-power switching.

Availability

ZTX458STOA is available at Aetrix Electronics and suitable for industrial power supply control, CRT horizontal deflection, automotive lamp driver, and high-voltage relay interface requiring stable component supply across extended temperature and voltage ranges.

Supply support for ZTX458STOA 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 Taiwan and China.

ZTX458STOA belongs to the ZTX series of high-voltage bipolar transistors developed for industrial and consumer power conversion, emphasizing ruggedness, wide temperature operation, and legacy package compatibility.

FAQ

Is ZTX458STOA RoHS compliant?

Yes, ZTX458STOA is RoHS compliant per Diodes Incorporated's product change notice PCN-2019-001, with lead-free matte tin plating on leads and halogen-free molding compound. It meets EU Directive 2011/65/EU and exemptions under Annex III.

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

The SOA curve in the datasheet specifies single-pulse limits up to 1 A at 40 V (10 ms), 0.5 A at 100 V (1 ms), and 0.1 A at 320 V (100 µs) at T_amb = 25°C. Derating is required above 25°C ambient per the thermal resistance R_θJA = 200°C/W.

Can ZTX458STOA replace ZTX457 in existing designs?

Yes - ZTX458STOA and ZTX457 share identical TO-92 package, pinout (C-B-E), and absolute maximum ratings. ZTX458STOA offers higher minimum h_FE (100 vs. 50) and tighter V_CE(sat) spec, improving base drive efficiency without layout changes.

Does ZTX458STOA require a base resistor in switching applications?

Yes - a series base resistor is mandatory to limit I_B and prevent thermal runaway. For I_C = 300 mA and h_FE = 100, I_B ≈ 3 mA; with 5 V drive, R_B ≈ 1.5 kΩ. Use 1% tolerance and 0.25 W rating for reliability.