Diodes Incorporated ZTX1149ASTZ

Overview

ZTX1149ASTZ from Diodes Incorporated (formerly Zetex) is a PNP silicon planar medium-power high-gain bipolar junction transistor in TO-92 package, rated for -25 V V_CEO, -3 A continuous collector current, and 135 MHz transition frequency. It delivers low V_CE(sat) down to -140 mV at IC = -1 A / IB = -7 mA and h_FE ≥ 195 at IC = -2 A, used in industrial DC-DC converter switching stages and linear regulator pass elements.

For engineers reviewing the ZTX1149ASTZ datasheet, ZTX1149ASTZ pinout, ZTX1149ASTZ application, or ZTX1149ASTZ equivalent, key selection criteria include verified PNP polarity, TO-92 mechanical compatibility, safe operating area under pulsed -10 A loads, thermal resistance profile up to +200°C junction temperature, and gain linearity across -10 mA to -5 A operating range.

Technical Context

This device operates as a medium-power PNP BJT with fixed-emitter bias topology, supporting both linear amplification and saturated switching modes. Its V_CE(sat) remains ≤ -200 mV up to -3 A with IB = -70 mA, and h_FE maintains ≥ 115 at IC = -5 A, enabling stable current gain in high-current driver circuits.

The transistor features low C_cb (50 pF at V_CB = -10 V), fast switching (t_on = 150 ns, t_off = 270 ns), and robust breakdown ratings: V_(BR)CBO = -30 V, V_(BR)CEO = -25 V, and V_(BR)EBO = -5 V - confirming suitability for 24 V rail protection and relay drive applications.

Key Specifications

Pinout & Package

Package: TO-92 (E-Line compatible), through-hole, epoxy-molded plastic case with standard lead spacing and orientation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar PNP medium-power transistor applications.

Compared with MJD2955G and ZTX1051A, ZTX1149ASTZ uniquely balances TO-92 mountability, 3 A continuous rating, and 135 MHz f_T - making it optimal for space-constrained, medium-speed, medium-current PNP switching where thermal mass is limited and gain stability across wide current range is critical.

Availability

ZTX1149ASTZ is available at Aetrix Electronics and suitable for industrial power supplies, automotive relay drivers, and DC motor control systems requiring stable component supply, long-lifecycle availability, and consistent parametric performance across manufacturing lots.

Supply support for ZTX1149ASTZ 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 acquired Zetex plc in 2008 and maintains its legacy high-performance discrete portfolio, emphasizing reliability, thermal robustness, and application-specific optimization for industrial and automotive markets.

ZTX1149ASTZ belongs to Zetex's medium-power bipolar transistor product line, designed specifically for high-gain, low-saturation switching in space-constrained 24 V systems where TO-92 mechanical fit and thermal resilience are mandatory.

FAQ

What is the maximum safe operating temperature for ZTX1149ASTZ?

The ZTX1149ASTZ has a specified junction temperature range of -55°C to +200°C. Its absolute maximum storage temperature matches this range. Derating begins at +25°C ambient, with total power dissipation reduced linearly to zero at +150°C ambient per the published derating curve. Thermal design must ensure T_j stays below 200°C under worst-case load and ambient conditions.

Can ZTX1149ASTZ be used in parallel configurations?

No - ZTX1149ASTZ is not characterized or recommended for paralleling. Its h_FE variation across lots and temperature-dependent V_BE(sat) mismatch would cause unequal current sharing. For higher current requirements, use a single higher-rated device like MJD2955G or implement external emitter resistors with careful thermal coupling, though this is not validated by Diodes Incorporated.

Is there a SPICE model available for ZTX1149ASTZ?

Yes - an official PSpice-compatible model was released by Zetex in 1997 (revision 10/1/97), including parameters for IS, BF, BR, VAF, VAR, CJE, CJC, TF, and TR. The model is publicly archived and usable for DC, AC, and transient analysis, but does not include thermal or aging effects. It is intended for design simulation only and not guaranteed for production correlation.

Does ZTX1149ASTZ meet RoHS and REACH requirements?

Yes - Diodes Incorporated certifies ZTX1149ASTZ as RoHS 2011/65/EU compliant and REACH SVHC-free per latest material declarations. The TO-92 package uses lead-free matte tin plating on leads and halogen-free epoxy molding compound. Full compliance documentation is available via Diodes' Quality Portal using the part's date code and lot traceability data.