Diodes Incorporated ZTX948

Overview

ZTX948 from Zetex Semiconductors (now Diodes Incorporated) is a PNP silicon planar medium-power high-current bipolar junction transistor designed for switching and linear amplification in industrial power control circuits. It delivers -4.5 A continuous collector current, -20 A peak pulse current, and exhibits V_CE(sat) as low as -45 mV at -0.5 A/-10 mA drive, with h_FE = 100–300 across 10 mA to 20 A, enabling robust load switching in DC-DC converters and motor drivers.

For engineers reviewing the ZTX948 datasheet, ZTX948 pinout, ZTX948 application, or ZTX948 equivalent, key selection criteria include its -20 V V_CEO, low saturation voltage under high current, gain linearity down to 10 mA, thermal resistance of 150 °C/W (junction-to-ambient), and TO-92 package compatibility - critical for space-constrained, thermally demanding medium-power designs.

Technical Context

The ZTX948 operates as a PNP BJT with base-emitter turn-on voltage of -860 mV at -5 A, supporting fast switching via 120 ns turn-on and 126 ns turn-off times under -4 A/-400 mA drive. Its f_T = 80 MHz and C_obo = 163 pF at -10 V enable stable operation up to mid-frequency switching applications.

Thermal design is enabled by R_th(j-amb) = 150 °C/W and R_th(j-case) = 50 °C/W, with safe operating area (SOA) curves validated for single-pulse and DC conditions up to +200 °C junction temperature, supporting reliability in automotive and industrial ambient environments.

Key Specifications

Pinout & Package

Package: TO-92 (E-Line compatible, 3-lead plastic case). Pin identification follows standard E-Line TO-92 orientation: 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 switching applications.

Compared with ZTX951, ZTX948 offers superior current density and lower saturation voltage at cost of reduced voltage rating; versus MJD2955, it trades package size and absolute power for PCB area savings and verified simulation support - making it optimal for compact, thermally managed medium-power designs.

Availability

ZTX948 is available at Aetrix Electronics and suitable for DC-DC converters, motor drivers, relay drivers, and linear current regulators requiring stable component supply with traceable lot history and extended lifecycle support.

Supply support for ZTX948 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, acquired by Diodes Incorporated in 2008, specialized in high-performance discrete semiconductors for power management and signal conditioning.

The ZTX series was engineered for industrial-grade medium-power switching and amplification, emphasizing gain consistency, thermal robustness, and SPICE-model fidelity in through-hole packages.

FAQ

Is ZTX948 RoHS compliant and halogen-free?

Yes. ZTX948 meets RoHS Directive 2011/65/EU and is halogen-free per IEC 61249-2-21. Diodes Incorporated's official product change notice (PCN #14-001) confirms lead-free matte tin plating and compliant molding compound for all ZTX948 lots manufactured after June 2014.

Can ZTX948 be used in parallel for higher current?

No - ZTX948 lacks built-in emitter ballasting resistors and exhibits positive thermal runaway risk when paralleled. Its h_FE variation and V_BE mismatch across units cause current hogging. For >4.5 A, use a single higher-rated device like MJD2955 or implement active current-sharing circuitry.

What is the maximum safe operating frequency for linear amplification?

At I_C = -100 mA and V_CE = -10 V, f_T = 80 MHz defines the unity-gain frequency. Practical linear amplification bandwidth is limited to ≤8 MHz for ≤1 dB gain flatness, based on measured h_FE roll-off and output capacitance (C_obo = 163 pF).

Does ZTX948 require a heatsink in standard TO-92 mounting?

Not for ≤1.2 W continuous dissipation at T_amb ≤ 50°C on a 1-inch² copper pad. At 1.58 W pulsed (duty cycle ≤2%), no heatsink is needed. Above 50°C ambient or >1.2 W DC, thermal derating applies per the published R_th(j-amb) curve - heatsinking becomes necessary beyond 75°C ambient.