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

Diodes Incorporated ZTX649STOA

Name: ZTX649STOA
Brand: Diodes Incorporated
SKU: ZTX649STOA
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: ZTX649STOA

Manufacturer:: Diodes Incorporated

Category:: Single Bipolar Transistors

Package:: E-Line-3, Formed Leads

Datasheet:: ZTX649STOA.pdf

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

Quantity:: RFQ Add To RFQ list

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Inventory:4,521

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Product details

Overview

ZTX649STOA from Diodes Incorporated is an NPN silicon planar medium-power transistor rated for 25 V V_CEO, 2 A continuous collector current, and 1 W power dissipation at 25°C ambient. It features low saturation voltage (V_CE(sat) = 0.12 V @ I_C = 1 A, I_B = 100 mA), high DC current gain (h_FE = 70–200), and 150–240 MHz transition frequency, enabling use in motor driver stages and DC-DC converter switching circuits.

For engineers reviewing the ZTX649STOA datasheet, ZTX649STOA pinout, ZTX649STOA application, or ZTX649STOA equivalent, key selection criteria include verified V_CE(sat) performance under 2 A load, thermal resistance to ambient (175 °C/W on PCB), safe operating area limits, switching speed (t_on = 55 ns, t_off = 300 ns), and TO-92 package compatibility with legacy E-Line footprints.

Technical Context

This discrete NPN bipolar junction transistor operates in linear or saturated switching mode with base-driven control logic. Its 25 V V_CEO rating supports 24 V rail applications, while 2 A I_C and 1 W P_tot enable medium-power load switching without forced cooling on standard PCBs.

The device delivers stable h_FE across 50 mA–2 A collector current (70–200), exhibits low V_BE(sat) (0.9–1.25 V), and maintains f_T ≥150 MHz at I_C = 100 mA, V_CE = 5 V - confirming suitability for high-speed switching in compact power stages.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	25 V - Maximum collector-emitter voltage before breakdown; defines max supply rail compatibility (e.g., 24 V systems)
I_C (continuous)	2 A - Sustained load current capability without derating; enables direct drive of small motors or solenoids
V_CE(sat)	0.12 V @ I_C=1 A, I_B=100 mA - Low conduction loss reduces heat generation in switching applications
h_FE	70–200 @ I_C=50 mA–2 A - Wide gain range ensures reliable base drive design across operating conditions
f_T	150–240 MHz - Supports fast switching up to ~100 kHz PWM with minimal delay and overshoot
R_th(j-amb)	175 °C/W - Thermal resistance on standard 1-in² copper PCB; determines max ambient temperature for full-power operation
t_on/t_off	55 ns / 300 ns - Verified turn-on/turn-off times under 500 mA load; critical for efficiency in DC-DC converters

Pinout & Package

Package: TO-92 (E-Line compatible, 3-lead plastic case). Standard through-hole mounting with 2.54 mm lead pitch.

Pin/Terminal	Circuit Role	Design Meaning
Emitter (E)	Current sink terminal	Connected to ground or low-side return path; carries full load current in common-emitter configuration
Base (B)	Control input	Receives current-limited drive signal (I_B ≈ I_C/10) to saturate or cut off the transistor
Collector (C)	Current source terminal	Connected to positive supply or inductive load; handles switched voltage up to 25 V and current up to 2 A

Key Features

Feature	Design Value
Low V_CE(sat)	0.12 V at 1 A - Reduces conduction loss by >40% vs. typical 0.2 V devices, improving thermal margin in sealed enclosures
High f_T	≥150 MHz - Enables clean square-wave switching at 100 kHz with <5% rise/fall time degradation
Wide h_FE range	70–200 - Allows single BOM part to support multiple base resistor values across production lots and temperature ranges
TO-92 footprint	E-Line compatible - Direct replacement for legacy ZTX649 and similar medium-power transistors without PCB redesign
100°C-rated I_CBO	10 µA @ T_amb=100°C - Confirmed leakage stability in industrial ambient environments

Applications

Motor Driver Stage

DC-DC Converter Switch

Use Scenario: Driving 12–24 V brushed DC motors in HVAC actuators and industrial valves.

IC Role / Device Role / Timing Role: Medium-power NPN switch controlling motor direction and PWM speed via microcontroller GPIO.

Use Value: 2 A I_C and 0.12 V V_CE(sat) minimize heat buildup during 100% duty cycle operation.

Use Scenario: High-efficiency buck converter output stage in 5–12 V point-of-load supplies.

IC Role / Device Role / Timing Role: Fast-switching NPN transistor in non-synchronous topology with 100 kHz PWM control.

Use Value: 55 ns t_on and 150 MHz f_T reduce switching losses and improve light-load regulation.

LED Array Driver

Relay/Solenoid Interface

Use Scenario: Constant-current driving of multi-segment LED arrays in signage and instrumentation panels.

IC Role / Device Role / Timing Role: Linear or PWM-controlled current sink for LED strings up to 2 A total.

Use Value: Stable h_FE over 50 mA–2 A ensures consistent brightness across dimming range without feedback compensation.

Use Scenario: Solid-state replacement for mechanical relays in PLC I/O modules and safety interlocks.

IC Role / Device Role / Timing Role: Inductive load switch with flyback diode integration and 25 V V_CEO headroom.

Use Value: 25 V rating and 6 A I_CM pulse capability safely handle 24 V relay coil transients and contact bounce energy.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
ZTX650STOA	V_CEO = 60 V, I_C = 2 A, V_CE(sat) = 0.25 V @ 1 A - higher voltage rating but higher saturation loss	Better suited for 48 V bus systems; less efficient in 24 V motor drivers due to +108 mV V_CE(sat)	Select when system voltage exceeds 25 V; avoid if minimizing conduction loss is critical
BCX56-16	V_CEO = 80 V, I_C = 1 A, h_FE = 100–250 - lower current rating, higher gain, TO-92 package	Limited to ≤1 A loads; preferred where precise current mirroring or low-base-drive requirements dominate	Choose for gain-critical analog interfaces; not suitable for 2 A motor or solenoid loads

Compared with ZTX649STOA, ZTX650STOA trades lower V_CE(sat) for higher voltage tolerance, while BCX56-16 offers superior h_FE at half the current capacity - making ZTX649STOA optimal for cost-sensitive, thermally constrained 24 V/2 A switching where both voltage headroom and conduction efficiency matter.

Availability

ZTX649STOA is available at Aetrix Electronics and suitable for motor driver stages, DC-DC converter switches, and relay/solenoid interface circuits requiring stable component supply and long-term industrial availability.

Supply support for ZTX649STOA 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 semiconductor company specializing in discrete, analog, and mixed-signal solutions for power management, signal integrity, and connectivity applications.

ZTX649STOA belongs to the ZTX series of medium-power bipolar transistors designed for robust, cost-effective switching in industrial controls, power conversion, and electromechanical actuation systems.

FAQ

What is the maximum safe operating temperature for ZTX649STOA?

The junction temperature must not exceed +200°C, and the storage temperature range is –55°C to +200°C. With R_th(j-amb) = 175 °C/W on a 1-in² PCB, continuous 1 W dissipation is only safe up to +75°C ambient - derating is required above that per the published thermal curve.

Can ZTX649STOA be used in avalanche mode?

No - ZTX649STOA is not rated or characterized for avalanche operation. Its absolute maximum V_CEO is 25 V, and exceeding this risks permanent breakdown. For inductive load switching, always use an external flyback diode rated for peak reverse voltage and current.

Is ZTX649STOA RoHS compliant and halogen-free?

Yes - ZTX649STOA 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 and complies with JEDEC J-STD-020 moisture sensitivity level 1 (unlimited floor life).

How does ZTX649STOA compare to ZTX649 in electrical performance?

ZTX649STOA is the enhanced, fully specified version of the legacy ZTX649. It adds guaranteed V_CE(sat) and h_FE limits across full I_C range, tighter f_T min specification (150 MHz), and updated thermal characterization - all validated per Issue 2 (April 1994) datasheet revision.

ZTX649STOA 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):: 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:: 240MHz

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

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

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

ZTX649STOA FAQ

1.How can I place an order for ZTX649STOA through Aetrix?

Please submit a Request for Quotation (RFQ) for ZTX649STOA 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 ZTX649STOA reliable?

The price and inventory of ZTX649STOA are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for ZTX649STOA is usually 5 days.

3.What payment methods are accepted for ZTX649STOA?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for ZTX649STOA transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for ZTX649STOA?

ZTX649STOA orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your ZTX649STOA 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 ZTX649STOA?

For technical support, including ZTX649STOA datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your ZTX649STOA requirements.

6.How does Aetrix verify that ZTX649STOA is sourced from the original manufacturer or authorized distributors?

All ZTX649STOA 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 ZTX649STOA meets industry standards.

7.What is the process for return or replacement of ZTX649STOA?

All ZTX649STOA units undergo pre-shipment inspection (PSI). If there is an issue with ZTX649STOA, 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 ZTX649STOA part is unused and in its original packaging.

Return procedure for ZTX649STOA:

1.Submit a request within 90 days.

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

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