Diodes Incorporated ZTX657STOB

Overview

ZTX657STOB from Diodes Incorporated is an NPN silicon planar medium-power high-voltage transistor with V_CEO = 300 V, I_C = 0.5 A continuous, P_tot = 1 W at T_amb = 25°C, h_FE ≥ 40 at I_C = 10 mA, and f_T = 30 MHz - used in high-voltage switching and linear regulator stages in industrial power supplies.

For engineers reviewing the ZTX657STOB datasheet, ZTX657STOB pinout, ZTX657STOB application, or ZTX657STOB equivalent, key selection criteria include verified 300 V V_CEO rating, TO-92-compatible E-Line package thermal limits, saturation voltage under defined I_C/I_B conditions, and h_FE consistency across 10–100 mA operating range.

Technical Context

This discrete NPN bipolar junction transistor is optimized for medium-power, high-voltage DC switching and analog amplification where breakdown margin and thermal stability are critical. It operates reliably from –55°C to +200°C junction temperature and supports pulse currents up to 1 A with validated safe operating area (SOA) curves for single-pulse and DC conditions.

Electrical behavior is characterized at 25°C with strict test conditions: V_(BR)CEO measured at I_C = 10 mA, I_CBO at V_CB = 200 V, and h_FE specified at two bias points (I_C = 10 mA and 100 mA), confirming gain stability across load ranges.

Key Specifications

Pinout & Package

Package: TO-92-compatible E-Line (3-lead plastic package, lead pitch 1.27 mm, body height 4.7 mm).

Key Features

Applications

Equivalent & Alternatives

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

Compared with ZTX657STOB, ZTX653STOB trades 100 V headroom for higher h_FE, while BCV61B retains voltage rating but sacrifices current capacity and package compatibility - making ZTX657STOB optimal for through-hole, 0.5 A, 300 V switching where thermal mass and layout flexibility matter.

Availability

ZTX657STOB is available at Aetrix Electronics and suitable for industrial power supply regulation, AC/DC adapter output stages, motor control gate drivers, and high-voltage relay interfaces requiring stable component supply and long-term manufacturability.

Supply support for ZTX657STOB 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-reliability power management and signal integrity solutions.

ZTX657STOB belongs to the ZTX series of high-voltage bipolar transistors designed specifically for industrial and automotive power conversion systems demanding robust SOA and extended temperature operation.

FAQ

What is the maximum allowable collector-emitter voltage for ZTX657STOB in continuous operation?

ZTX657STOB has a guaranteed V_CEO rating of 300 V under DC conditions at T_j ≤ 150°C. Derating is required above 25°C ambient per the thermal resistance curve; at 70°C ambient, maximum usable V_CEO drops to approximately 260 V to maintain safe junction temperature.

Can ZTX657STOB be used in switching applications above 100 kHz?

Yes - its f_T of 30 MHz supports switching frequencies up to ~1–2 MHz in low-duty-cycle pulse applications. However, practical switching speed is limited by stored charge and base drive strength; measured t_f and t_r are 0.4 µs and 0.6 µs respectively at I_C/I_B = 10, enabling clean transitions below 500 kHz with proper drive.

Is ZTX657STOB RoHS compliant and halogen-free?

Yes - ZTX657STOB meets RoHS Directive 2011/65/EU and is certified halogen-free per IEC 61249-2-21. The device carries the "Green" designation in Diodes Incorporated's product marking system and uses matte tin lead finish on all leads.

Does ZTX657STOB require a heatsink in 1 W continuous operation?

No - at 25°C ambient and free-air mounting, ZTX657STOB dissipates 1 W within its rated P_tot limit without external heatsinking. However, thermal resistance θ_JA is 125°C/W; above 45°C ambient, a minimum copper pad (≥1 cm²) is recommended to maintain T_j < 150°C.