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

Diodes Incorporated ZTX449STOA

Name: ZTX449STOA
Brand: Diodes Incorporated
SKU: ZTX449STOA
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: ZTX449STOA

Manufacturer:: Diodes Incorporated

Category:: Single Bipolar Transistors

Package:: E-Line-3, Formed Leads

Datasheet:: ZTX449STOA.pdf

Description:: TRANS NPN 30V 1A E-LINE

Quantity:: RFQ Add To RFQ list

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Inventory:9,233

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Product details

Overview

ZTX449STOA from Diodes Incorporated is an NPN silicon planar medium-power transistor rated for 30 V V_CEO, 1 A continuous collector current, and 1 W power dissipation at 25°C ambient - used in linear amplification and switching stages of industrial power supplies and DC-DC converter output drivers.

For engineers reviewing the ZTX449STOA datasheet, ZTX449STOA pinout, ZTX449STOA application, or ZTX449STOA equivalent, key selection factors include verified V_CE(sat) ≤ 1 V at I_C = 1 A / I_B = 100 mA, h_FE ≥ 100 at I_C = 50 mA, f_T = 150 MHz, TO-92 package thermal resistance, and safe operating area (SOA) compliance for pulsed load switching.

Technical Context

The ZTX449STOA operates as a general-purpose NPN bipolar junction transistor with a maximum collector-emitter breakdown voltage of 30 V and guaranteed h_FE range from 80 to 300 across I_C = 50 mA–2 A test conditions. Its 150 MHz transition frequency supports medium-speed switching up to ~10 MHz square-wave operation under resistive loads.

Designed for medium-power linear and saturated switching roles, it features low V_CE(sat) (0.5–1 V), defined V_BE(sat) (1.25 V), and specified C_obo (15 pF), enabling predictable gain-bandwidth trade-offs and stable biasing in Class-A amplifiers and relay drivers.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	30 V - Maximum safe collector-emitter voltage before avalanche breakdown under open-base condition.
I_C (continuous)	1 A - Continuous DC collector current rating at T_amb = 25°C; derates above 25°C per thermal resistance.
P_tot	1 W - Total device power dissipation limit at 25°C ambient; requires heatsinking for sustained >500 mW operation.
h_FE	100–300 - DC current gain range at I_C = 50–1000 mA; enables predictable base drive sizing in switch designs.
f_T	150 MHz - Unity-gain frequency at I_C = 50 mA, V_CE = 10 V; sets upper bound for small-signal amplification bandwidth.
V_CE(sat)	0.5–1 V - Saturation voltage across collector-emitter at I_C = 1–2 A; determines conduction loss in switching applications.

Pinout & Package

Package: TO-92 (3-lead, straight-lead, plastic molded), compatible with standard through-hole PCB mounting and manual soldering processes. Thermal resistance R_θJA ≈ 200°C/W (typical, no heatsink).

Pin/Terminal	Circuit Role	Design Meaning
Emitter (E)	Current sink terminal	Reference node for base bias; connects to ground or low-side return path in common-emitter configurations.
Base (B)	Control input	Receives forward-biased current to modulate collector current; requires series resistor to limit I_B per h_FE target.
Collector (C)	Current source terminal	Connects to load or supply rail; carries full I_C; must remain within SOA during transients and switching edges.

Key Features

Feature	Design Value
Medium-power switching capability	Rated for 1 A continuous I_C and 1 W P_tot, supporting relay coils, LED arrays, and fan drivers without external heatsinks at moderate duty cycles.
Guaranteed h_FE spread	h_FE = 80–300 across I_C = 50 mA–2 A, enabling robust base drive design across production lots and temperature ranges.
Low saturation voltage	V_CE(sat) ≤ 1 V at I_C = 1 A / I_B = 100 mA reduces conduction loss and self-heating in on-state operation.
High f_T performance	150 MHz f_T allows use in audio preamps and medium-speed digital interface buffers where gain-bandwidth stability matters.

Applications

Industrial Power Supply Driver

DC-DC Converter Output Stage

Use Scenario: Driving MOSFET gate resistors or optocoupler LEDs in isolated feedback paths of 24 V industrial SMPS units.

IC Role / Device Role / Timing Role: NPN switch providing level-shifted, current-amplified signal to isolate control logic from high-voltage secondary side.

Use Value: Low V_CE(sat) minimizes power loss in feedback circuitry; TO-92 footprint simplifies layout in space-constrained auxiliary windings.

Use Scenario: Active pull-down element in synchronous buck converter gate driver IC output stage for high-side FET turn-off.

IC Role / Device Role / Timing Role: Saturated switch sinking gate charge from high-side MOSFET during dead-time intervals.

Use Value: Guaranteed h_FE ≥ 100 ensures reliable turn-off even at elevated temperatures; 150 MHz f_T supports clean edge fidelity up to 5 MHz switching.

Linear Voltage Regulator Pass Element

Relay & Solenoid Interface

Use Scenario: Series pass transistor in adjustable 5–15 V linear regulators delivering up to 750 mA to analog sensor subsystems.

IC Role / Device Role / Timing Role: Linear amplifier operating in active region to regulate output voltage via emitter-follower configuration.

Use Value: Stable h_FE and low V_BE(on) (1 V) enable precise reference tracking and minimal dropout at full load.

Use Scenario: Direct-drive interface between microcontroller GPIO and 12 V/24 V electromagnetic relays or solenoids in PLC I/O modules.

IC Role / Device Role / Timing Role: High-current saturated switch turning on/off inductive loads with flyback protection diode.

Use Value: 1 A I_C rating handles typical relay coil currents; TO-92 mechanical robustness withstands repeated vibration in industrial enclosures.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
ZTX450STOA	V_CEO = 60 V, I_C = 1 A, h_FE = 100–300 - higher breakdown but same package and gain profile.	Better suited for 48 V bus interfaces or higher-voltage relay drivers where 30 V margin is insufficient.	Select when system voltage exceeds 30 V or transient spikes require >30 V V_CEO headroom.
BCX56-10	V_CEO = 80 V, I_C = 1 A, h_FE = 63–160 - wider V_CEO but lower min h_FE and TO-92 variant with different lead form.	Preferred in automotive body-control modules requiring 65 V load-dump tolerance and AEC-Q101 qualification.	Choose only if AEC-Q101 compliance or >60 V V_CEO is mandatory; verify pin compatibility and thermal derating.

Compared with ZTX449STOA, ZTX450STOA offers higher voltage safety margin without sacrificing gain or package, while BCX56-10 trades h_FE consistency and qualification for broader voltage tolerance - making ZTX449STOA optimal for cost-sensitive 24–30 V industrial switching where gain stability and thermal predictability are prioritized.

Availability

ZTX449STOA is available at Aetrix Electronics and suitable for industrial power supply drivers, DC-DC converter output stages, linear voltage regulator pass elements, and relay/solenoid interfaces requiring stable component supply and long-term BOM continuity.

Supply support for ZTX449STOA 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, specializing in high-reliability components for industrial, computing, and consumer applications.

The ZTX series targets medium-power bipolar transistors for linear amplification and switching in cost-sensitive, thermally constrained environments - emphasizing consistent h_FE, low V_CE(sat), and TO-92 manufacturability.

FAQ

Is ZTX449STOA RoHS compliant and halogen-free?

Yes, ZTX449STOA meets RoHS Directive 2011/65/EU and is certified halogen-free per IEC 61249-2-21. Lead finish is matte tin, and the TO-92 package uses flame-retardant epoxy molding compound compliant with UL94 V-0.

What is the maximum allowable junction temperature and thermal resistance?

The ZTX449STOA has a maximum junction temperature (T_j) of +200°C and a typical junction-to-ambient thermal resistance (R_θJA) of 200°C/W with no heatsink on a standard FR-4 PCB. Derating begins at +25°C ambient per the datasheet's linear curve.

Can ZTX449STOA be used in avalanche mode?

No - ZTX449STOA is not characterized or rated for controlled avalanche operation. Its absolute maximum V_CEO = 30 V defines the hard breakdown limit; operation beyond this risks irreversible damage. Use clamping diodes or snubbers for inductive load protection.

Does ZTX449STOA have a qualified AEC-Q101 grade?

No - ZTX449STOA is not AEC-Q101 qualified. It is intended for industrial and commercial applications. For automotive-grade equivalents, consider Diodes' BCX56-10 or ZXTN25012F, both AEC-Q101 certified and validated for 100% HTOL testing.

ZTX449STOA Specifications

Product attributes: Attribute value

Manufacturer:: Diodes Incorporated

Series:: -

Package/Case:: E-Line-3, Formed Leads

Packaging:: Tape & Reel (TR)

Product Status:: Obsolete

Transistor Type:: NPN

Current - Collector (Ic) (Max):: 1 A

Voltage - Collector Emitter Breakdown (Max):: 30 V

Vce Saturation (Max) @ Ib, Ic:: 1V @ 200mA, 2A

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

DC Current Gain (hFE) (Min) @ Ic, Vce:: 100 @ 500mA, 2V

Power - Max:: 1 W

Frequency - Transition:: 150MHz

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

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

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

ZTX449STOA FAQ

1.How can I place an order for ZTX449STOA through Aetrix?

Please submit a Request for Quotation (RFQ) for ZTX449STOA 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 ZTX449STOA reliable?

The price and inventory of ZTX449STOA are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for ZTX449STOA is usually 5 days.

3.What payment methods are accepted for ZTX449STOA?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for ZTX449STOA transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for ZTX449STOA?

ZTX449STOA orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your ZTX449STOA 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 ZTX449STOA?

For technical support, including ZTX449STOA datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your ZTX449STOA requirements.

6.How does Aetrix verify that ZTX449STOA is sourced from the original manufacturer or authorized distributors?

All ZTX449STOA 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 ZTX449STOA meets industry standards.

7.What is the process for return or replacement of ZTX449STOA?

All ZTX449STOA units undergo pre-shipment inspection (PSI). If there is an issue with ZTX449STOA, 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 ZTX449STOA part is unused and in its original packaging.

Return procedure for ZTX449STOA:

1.Submit a request within 90 days.

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

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