Diodes Incorporated ZTX955STOB

Overview

ZTX955STOB from Diodes Incorporated is a PNP silicon planar medium-power high-current transistor rated for -3 A continuous collector current, -140 V V_CEO, and 1.2 W power dissipation at 25°C ambient. It delivers very low saturation voltage (e.g., -90 mV at I_C = -1 A, I_B = -100 mA), excellent DC current gain (h_FE = 140 at I_C = -3 A), and operates from -55°C to +200°C - used in industrial motor control output stages and high-reliability DC-DC converter switching circuits.

For engineers reviewing the ZTX955STOB datasheet, ZTX955STOB pinout, ZTX955STOB application, or ZTX955STOB equivalent, key selection criteria include verified PNP polarity, TO-92-compatible E-Line package compatibility, guaranteed -140 V V_CEO rating, low V_CE(sat) under high-current switching, and thermal resistance of 150°C/W junction-to-ambient under PCB-mount conditions.

Technical Context

This discrete PNP bipolar junction transistor is optimized for medium-power linear and switching applications where high current handling and low on-state loss are critical. Its design supports stable gain up to -3 A (h_FE ≥ 100) and features a transition frequency of 110 MHz, enabling use in fast-switching analog and pulse circuits.

The device uses a planar silicon structure with emitter-base breakdown voltage of -6 V and collector-base breakdown voltage of -180 V. Thermal performance is characterized by R_th(j-amb) = 150°C/W (PCB-mounted) and R_th(j-case) = 50°C/W, supporting operation up to +200°C junction temperature.

Key Specifications

Pinout & Package

Package: E-Line TO-92-compatible (3-321 outline), plastic molded, through-hole mounting. Pin identification: viewed from flat side with leads down, left-to-right is Emitter (E), Base (B), Collector (C).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar PNP high-current transistor applications.

Compared with MJD2955G and ZTX951, ZTX955STOB uniquely balances TO-92 mountability, -140 V blocking, and -3 A continuous current in a single package - making it optimal for compact, high-voltage industrial controls where heatsink area is limited.

Availability

ZTX955STOB is available at Aetrix Electronics and suitable for industrial motor control, DC-DC converter output stages, and automotive body control modules requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for ZTX955STOB 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 semiconductor company specializing in discrete, analog, and mixed-signal devices for industrial, computing, consumer, and communications markets.

ZTX955STOB belongs to Diodes' ZTX series of high-reliability bipolar transistors, designed specifically for medium-power switching and linear applications demanding wide temperature operation and robust SOA performance.

FAQ

Is ZTX955STOB RoHS compliant and lead-free?

Yes, ZTX955STOB is RoHS compliant and manufactured with lead-free terminations per Diodes Incorporated's standard product specifications. The device meets JEDEC J-STD-020 moisture sensitivity level (MSL) 1 and is compatible with standard Pb-free reflow profiles.

What is the maximum safe operating area (SOA) limit at 100°C case temperature?

At T_C = 100°C, the SOA curve shows a maximum single-pulse I_C of approximately -4.5 A at V_CE = -50 V (100 µs pulse width). Derating is required above 25°C ambient per the published thermal impedance curves in the datasheet Figure 3-323.

Can ZTX955STOB be used in parallel for higher current handling?

No - ZTX955STOB lacks built-in emitter ballasting resistors and exhibits positive temperature coefficient of V_BE(sat), making current sharing unstable without external balancing components. Parallel operation requires individual base resistors and thermal coupling verification.

Does the SPICE model include thermal and SOA behavioral elements?

The official Diodes Incorporated SPICE model for ZTX955STOB includes temperature-dependent parameters (V_BE, β, I_S) and basic thermal network elements, but does not model secondary breakdown or dynamic SOA limits - those require manual implementation using published transient thermal impedance data.