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Home > Products > Discrete Semiconductor Products > Transistors > Bipolar (BJT) > Single Bipolar Transistors

Diodes Incorporated ZTX749

Name: ZTX749
Brand: Diodes Incorporated
SKU: ZTX749
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: ZTX749

Manufacturer:: Diodes Incorporated

Category:: Single Bipolar Transistors

Package:: E-Line-3

Datasheet:: ZTX749.pdf

Description:: TRANS PNP 25V 2A E-LINE

Quantity:: RFQ Add To RFQ list

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Inventory:3,580

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Product details

Overview

ZTX749 from Diodes Incorporated is a PNP silicon planar medium-power bipolar junction transistor rated for -25 V V_CEO, -2 A continuous collector current, and low saturation voltage (V_CE(sat) = -0.23 V at I_C = 1 A, I_B = -100 mA). It operates across -55 °C to +200 °C and is commonly used in linear regulators, relay drivers, and DC-DC converter output stages.

For engineers reviewing the ZTX749 datasheet, ZTX749 pinout, ZTX749 application, or ZTX749 equivalent, key selection criteria include verified PNP polarity, TO-92-compatible package thermal resistance (R_th(j-case) = 70 °C/W), pulsed switching performance (t_on = 40 ns, t_off = 450 ns), and h_FE range of 70–300 across I_C = -50 mA to -2 A.

Technical Context

The ZTX749 is a medium-power PNP BJT optimized for linear and switching operation in industrial power control circuits. Its design supports stable DC biasing with h_FE ≥ 70 at I_C = -1 A and V_CE = -2 V, and maintains low V_CE(sat) (-0.12 V min) under high base drive (I_B = -100 mA).

It features a transition frequency f_T of 100–160 MHz at I_C = -100 mA and V_CE = -5 V, enabling use in moderate-speed switching applications. Output capacitance C_obo is 55–100 pF at V_CB = -10 V, supporting predictable turn-off behavior in inductive load interfaces.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	-25 V - Maximum safe collector-emitter voltage before breakdown in common-emitter configuration
I_C (cont.)	-2 A - Continuous DC collector current rating at T_amb = 25 °C with derating above
V_CE(sat)	-0.23 V @ I_C = -1 A, I_B = -100 mA - Low conduction loss in saturated switch mode
h_FE	70–300 - Current gain range across operating points, supporting reliable bias design
f_T	100–160 MHz - Enables use in sub-200 MHz switching and RF amplifier stages
R_th(j-case)	70 °C/W - Thermal resistance from junction to case, critical for heatsink sizing in TO-92 mounting

Pinout & Package

Package: TO-92 compatible (E-Line variant), epoxy-molded, through-hole mount with 3-pin vertical lead frame. Pin identification follows standard EBC (Emitter-Base-Collector) sequence when viewed with flat side facing user and leads downward.

Pin/Terminal	Circuit Role	Design Meaning
E (Emitter)	Current exit terminal for PNP device	Connected to higher potential rail in common-emitter switch; requires robust trace routing for -2 A paths
B (Base)	Control input for minority-carrier injection	Requires current-limited drive (e.g., 5–10% of I_C) to ensure saturation without overdrive
C (Collector)	Current entry terminal for PNP device	Typically tied to load and ground return; thermally coupled to PCB copper for R_th(j-amb) = 116 °C/W

Key Features

Feature	Design Value
Low V_CE(sat)	-0.12 V minimum enables <100 mW conduction loss at 1 A, reducing thermal stress in linear regulators
Wide temperature range	-55 °C to +200 °C junction operation supports under-hood automotive and industrial motor control
Pulsed switching speed	t_on = 40 ns / t_off = 450 ns allows >100 kHz PWM operation in DC-DC feedback loops
High f_T	160 MHz typical supports small-signal amplification up to VHF band in sensor interface front-ends

Applications

Linear Voltage Regulator

Relay Driver Circuit

Use Scenario: Used as pass transistor in adjustable negative-voltage LDOs delivering up to 1.5 A.

IC Role / Device Role / Timing Role: PNP pass element controlling output voltage via emitter-follower configuration.

Use Value: Low V_CE(sat) minimizes dropout voltage; h_FE stability ensures consistent regulation across load steps.

Use Scenario: Drives 12 V/500 mA electromagnetic relay coil in PLC I/O modules.

IC Role / Device Role / Timing Role: Saturated switch sinking relay current from V_CC to ground.

Use Value: Fast t_off (450 ns) reduces contact bounce during deactivation; rugged SOA supports inductive kickback.

DC-DC Converter Output Stage

Motor Control H-Bridge Leg

Use Scenario: Active clamp or synchronous rectifier driver in isolated flyback converters.

IC Role / Device Role / Timing Role: High-side PNP switch managing energy transfer timing in secondary-side regulation.

Use Value: 200 °C max T_j rating accommodates transient thermal spikes during burst-mode operation.

Use Scenario: Low-side switch in brushed DC motor half-bridge for industrial actuators.

IC Role / Device Role / Timing Role: Current sink for motor winding commutation controlled by microcontroller GPIO.

Use Value: Verified -6 A peak pulse rating handles startup surge; TO-92 footprint simplifies layout in space-constrained enclosures.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
ZTX750	Same TO-92 package; higher V_CEO (-30 V) but lower h_FE (min 50 @ I_C = -1 A)	Better suited for higher-voltage bus interfaces where gain margin is less critical	Select when system V_CC exceeds 25 V but load current remains ≤1.5 A
MPSA92	Higher V_CEO (-300 V), lower I_C (-500 mA), slower switching (t_off ≈ 1 µs)	Designed for high-voltage, low-current signal switching-not power switching	Use only in HV bias networks or protection circuits, not in power delivery paths

Compared with ZTX749, ZTX750 trades gain for voltage headroom while retaining thermal performance, whereas MPSA92 serves entirely different high-voltage/low-current roles-neither is a drop-in replacement, and selection must align with actual V_CE, I_C, and switching speed requirements.

Availability

ZTX749 is available at Aetrix Electronics and suitable for linear voltage regulators, relay drivers, DC-DC converter output stages, and motor control H-bridge legs requiring stable component supply across extended temperature ranges.

Supply support for ZTX749 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 and manufacturing operations across Asia and the Americas.

The ZTX series targets industrial-grade medium-power bipolar transistors, emphasizing ruggedness, wide temperature operation, and repeatable parametric performance for mission-critical power control applications.

FAQ

Is ZTX749 RoHS compliant and halogen-free?

Yes, ZTX749 meets RoHS Directive 2011/65/EU and is certified halogen-free per IEC 61249-2-21. The TO-92 package uses lead-free matte tin plating on leads and complies with JEDEC J-STD-020 moisture sensitivity level 1 (unlimited floor life at ≤30 °C/85% RH).

What is the maximum safe continuous power dissipation at 70 °C ambient?

At T_amb = 70 °C, derated power is 5.7 W × (1 − (70 − 25)/175) = 4.1 W, based on R_th(j-amb) = 175 °C/W. For sustained operation, PCB copper area ≥1 in² is required to achieve R_th(j-amb) = 116 °C/W, raising allowable power to ~4.9 W at 70 °C.

Can ZTX749 be used in avalanche mode?

No-ZTX749 is not characterized or rated for controlled avalanche operation. Its safe operating area (SOA) curve defines only forward-biased second breakdown limits. Operation beyond V_CEO = -25 V risks irreversible junction damage, even with current limiting.

Does ZTX749 require a base resistor in switching applications?

Yes-a series base resistor is mandatory to limit I_B and prevent thermal runaway. For I_C = -2 A saturation, I_B ≥ -200 mA is needed (h_FE min ≈ 10 at that point); a 22 Ω resistor from a -5 V logic source delivers -227 mA, ensuring hard saturation without excessive base power dissipation.

ZTX749 Specifications

Product attributes: Attribute value

Manufacturer:: Diodes Incorporated

Series:: -

Package/Case:: E-Line-3

Packaging:: Bulk

Product Status:: Active

Transistor Type:: PNP

Current - Collector (Ic) (Max):: 2 A

Voltage - Collector Emitter Breakdown (Max):: 25 V

Vce Saturation (Max) @ Ib, Ic:: 500mV @ 200mA, 2A

Current - Collector Cutoff (Max):: 100nA (ICBO)

DC Current Gain (hFE) (Min) @ Ic, Vce:: 100 @ 1A, 2V

Power - Max:: 1 W

Frequency - Transition:: 160MHz

Operating Temperature:: -55°C ~ 200°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: E-Line (TO-92 compatible)

ZTX749 FAQ

1.How can I place an order for ZTX749 through Aetrix?

Please submit a Request for Quotation (RFQ) for ZTX749 on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for ZTX749 reliable?

The price and inventory of ZTX749 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for ZTX749 is usually 5 days.

3.What payment methods are accepted for ZTX749?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for ZTX749 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for ZTX749?

ZTX749 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your ZTX749 order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for ZTX749?

For technical support, including ZTX749 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your ZTX749 requirements.

6.How does Aetrix verify that ZTX749 is sourced from the original manufacturer or authorized distributors?

All ZTX749 products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that ZTX749 meets industry standards.

7.What is the process for return or replacement of ZTX749?

All ZTX749 units undergo pre-shipment inspection (PSI). If there is an issue with ZTX749, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The ZTX749 part is unused and in its original packaging.

Return procedure for ZTX749:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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