Diodes Incorporated ZTX951STOB

Overview

ZTX951STOB from Diodes Incorporated is a PNP silicon planar medium-power high-current transistor rated for −4 A continuous collector current, −60 V V_CEO, and 1.2 W power dissipation at 25°C ambient. It features very low saturation voltage (−120 mV at −2 A/−200 mA), excellent DC current gain (h_FE = 120 at −4 A), and operates across −55°C to +200°C junction temperature range - used in industrial DC-DC converter output stages and motor drive current switches.

For engineers reviewing the ZTX951STOB datasheet, ZTX951STOB pinout, ZTX951STOB application, or ZTX951STOB equivalent, key selection criteria include verified V_CE(sat) performance under high-current switching, thermal resistance (R_th(j-amb) = 150°C/W), safe operating area (SOA) compliance at pulse widths down to 0.1 ms, and TO-92-compatible E-Line package mechanical compatibility.

Technical Context

This PNP bipolar junction transistor is optimized for linear and switching operation in medium-power analog and power control circuits. Its design emphasizes low V_CE(sat) across IC = −100 mA to −4 A, stable h_FE up to −10 A, and robust SOA with single-pulse capability up to 15 A peak.

Thermal performance is defined by R_th(j-case) = 50°C/W and R_th(j-amb) = 150°C/W on 1-inch² PCB copper. The device supports pulsed operation (duty cycle ≤2%, pulse width = 300 µs) and includes SPICE modeling support for circuit simulation validation.

Key Specifications

Pinout & Package

E-Line TO-92 compatible package (3-lead plastic case, JEDEC TO-92 outline), lead-forming option STOB denotes straight leads, tinned finish, tape-and-reel packaging.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ZTX951STOB, ZTX953STOB trades gain for higher voltage rating in identical form factor, while MJD2955G delivers higher current capacity at the cost of thermal management complexity and missing simulation support.

Availability

ZTX951STOB is available at Aetrix Electronics and suitable for industrial motor drives, DC-DC converter output stages, and linear regulator pass elements requiring stable component supply with consistent TO-92 mechanical fit and thermal performance.

Supply support for ZTX951STOB 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 China, Taiwan, and the U.S.

The ZTX series targets medium-power bipolar transistors for industrial, automotive, and computing applications where reliability, thermal robustness, and SPICE-model-supported design are required.

FAQ

What is the maximum safe continuous collector current for ZTX951STOB at 75°C ambient?

At 75°C ambient, the continuous collector current must be derated from −4 A using the 150°C/W thermal resistance. With T_j(max) = 200°C, allowable ΔT = 125°C, so P_diss ≤ 0.833 W. At V_CE(sat) ≈ −150 mV, this limits I_C to approximately −3.3 A for sustained operation without exceeding junction temperature.

Does ZTX951STOB support base-emitter reverse bias beyond −6 V?

No. The absolute maximum V_EB is −6 V per datasheet; exceeding this risks permanent degradation of the emitter-base junction. For applications requiring reverse base-emitter tolerance, external clamping diodes or alternative devices with higher V_EBO (e.g., ZTX953STOB at −8 V) must be used.

Can ZTX951STOB be used in parallel configurations for higher current?

Parallel operation is not recommended due to gain and V_BE mismatch between units, which causes current imbalance. Even with matched h_FE, thermal runaway risk remains without individual emitter resistors and shared heatsinking - use a single higher-rated device like MJD2955G instead.

Is the SPICE model for ZTX951STOB compatible with LTspice?

Yes - Diodes Incorporated provides an industry-standard .lib file with subcircuit definitions fully compatible with LTspice, PSpice, and Spectre. The model includes temperature-dependent parameters, junction capacitance, and accurate SOA boundary representation for transient analysis.