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

Diodes Incorporated ZTX651

Name: ZTX651
Brand: Diodes Incorporated
SKU: ZTX651
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: ZTX651

Manufacturer:: Diodes Incorporated

Category:: Single Bipolar Transistors

Package:: E-Line-3

Datasheet:: ZTX651.pdf

Description:: TRANS NPN 60V 2A E-LINE

Quantity:: RFQ Add To RFQ list

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Inventory:4,066

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Product details

Overview

ZTX651 from Zetex Semiconductors (now Diodes Incorporated) is an NPN silicon planar medium-power transistor designed for linear amplification and switching in industrial control, power supply regulation, and relay drivers. It delivers 2 A continuous collector current, 60 V V_CEO, 175 MHz transition frequency, and low 0.23 V typical V_CE(sat) at I_C=2 A/I_B=200 mA - enabling efficient high-current switching in compact TO-92 packages.

For engineers reviewing the ZTX651 datasheet, ZTX651 pinout, ZTX651 application, or ZTX651 equivalent, key selection criteria include verified V_CEO/I_C derating curves, thermal resistance to ambient (116 °C/W on PCB), safe operating area under pulsed conditions, and saturation voltage consistency across temperature.

Technical Context

The ZTX651 operates as a general-purpose NPN bipolar junction transistor with fixed gain structure optimized for medium-power analog and digital switching. Its 60 V V_CEO rating supports operation in 48 V rail systems, while its 175 MHz f_T enables stable performance up to audio-frequency switching and moderate-speed digital logic interfacing.

Thermal design relies on its specified R_th(j–amb) of 116 °C/W when mounted on ≥1 in² copper PCB, and its safe operating area (SOA) is defined for single-pulse durations down to 100 µs - critical for inductive load switching with flyback energy management.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	60 V - Maximum sustainable collector-emitter voltage before breakdown under open-base conditions; defines upper limit for DC/peak supply rails.
I_C (continuous)	2 A - Continuous DC collector current capability at T_amb = 25°C; derates linearly above 25°C per 5.7 mW/°C.
V_CE(sat)	0.23 V typ. @ I_C=2 A, I_B=200 mA - Low saturation voltage minimizes conduction loss and self-heating in switching applications.
f_T	175 MHz @ I_C=100 mA, V_CE=5 V - Transition frequency confirms usable bandwidth for audio amplification and fast-switching control signals.
R_th(j–amb)	116 °C/W - Thermal resistance from junction to ambient on 1 in² PCB copper; determines maximum power dissipation at target case temperature.
t_off	800 ns @ I_C=500 mA, V_CC=10 V - Turn-off delay limits maximum switching frequency in hard-switched topologies.

Pinout & Package

Package: TO-92 (E-Line compatible), through-hole, epoxy-molded plastic case with standard lead spacing and orientation. Mounting requires ≥1 in² copper pour for rated thermal performance.

Pin/Terminal	Circuit Role	Design Meaning
E (Emitter)	Current sink terminal	Reference node for base drive; connects to ground or low-side return path in common-emitter configurations.
B (Base)	Control input	Receives forward-biased current to enable conduction; requires ~200 mA drive for full saturation at 2 A collector load.
C (Collector)	Current source terminal	Connects to load and positive supply; carries full switched current and must be routed with adequate trace width and thermal relief.

Key Features

Feature	Design Value
Medium-power switching capability	Rated for 2 A continuous I_C and 60 V V_CEO, supporting relay coils, solenoids, and DC-DC converter switches without external heatsinking at moderate duty cycles.
Low V_CE(sat)	0.23 V typical at full 2 A load reduces conduction loss to <0.5 W, improving efficiency and easing thermal management in space-constrained designs.
High f_T	175 MHz enables stable small-signal amplification up to ~20 MHz and reliable digital switching up to ~1–2 MHz with controlled edge rates.
Robust SOA	Defined safe operating area includes 10 ms to DC boundaries, allowing use in inductive switching with snubbers or freewheeling diodes without secondary breakdown risk.

Applications

Industrial Relay Drivers

Linear Voltage Regulators

Use Scenario: Driving 24 V/1 A electromagnetic relays in PLC output modules with 3.3 V or 5 V microcontroller GPIO.

IC Role / Device Role / Timing Role: NPN switch configured in common-emitter topology, sinking relay coil current to ground upon base activation.

Use Value: 0.23 V V_CE(sat) limits relay coil voltage drop to ≤0.5 V, ensuring >95% nominal coil energization and reliable contact closure.

Use Scenario: Pass transistor in adjustable 3-terminal linear regulator delivering up to 1.5 A at 5–12 V output from unregulated 15–24 V input.

IC Role / Device Role / Timing Role: Series pass element controlling output voltage via base bias from error amplifier feedback loop.

Use Value: 60 V V_CEO accommodates input transients; 116 °C/W R_th(j–amb) allows 1.5 A operation with <40°C rise on standard PCB layout.

DC Motor Speed Control

Power Supply OR-ing Circuits

Use Scenario: Low-side PWM switch controlling brushed DC motors (≤24 V, ≤1.8 A) in battery-powered tools and actuators.

IC Role / Device Role / Timing Role: Synchronous switching element modulating average motor voltage via 1–20 kHz PWM duty cycle.

Use Value: 800 ns t_off supports clean turn-off at 20 kHz, minimizing shoot-through risk and reducing audible motor whine.

Use Scenario: Reverse-polarity protection and OR-ing diode replacement in dual-input 12 V power supplies (e.g., main + backup battery).

IC Role / Device Role / Timing Role: Active NPN switch replacing Schottky diode to reduce forward drop and improve efficiency in redundant power paths.

Use Value: 0.23 V V_CE(sat) cuts conduction loss by >60% vs. 0.45 V Schottky, increasing system runtime and reducing heat generation.

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
MJD127G	TO-220 package, 100 V V_CEO, 2 A I_C, higher P_tot (15 W), R_th(j–amb) = 30 °C/W with heatsink	Requires heatsink for >1 A continuous; suited for higher-voltage, higher-power industrial loads	Select when V_CEO > 60 V or thermal budget permits larger package and heatsink integration
BCP56-10	SOT-223 package, 80 V V_CEO, 1 A I_C, lower P_tot (1.5 W), surface-mount only	Limited to ≤1 A continuous; better for automated assembly but lower power density than ZTX651	Select when board space is constrained and peak load current remains ≤1 A with adequate PCB copper cooling

Compared with MJD127G and BCP56-10, the ZTX651 uniquely balances 2 A capability, 60 V rating, and TO-92 manufacturability - making it optimal for cost-sensitive, through-hole assembled systems needing robust medium-power switching without heatsinks.

Availability

ZTX651 is available at Aetrix Electronics and suitable for industrial relay drivers, linear voltage regulators, DC motor controllers, and power supply OR-ing circuits requiring stable component supply and long-term obsolescence resilience.

Supply support for ZTX651 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 precision analog and power-efficient switching applications.

The ZTX series was engineered for ruggedized medium-power linear and switching roles in industrial, automotive, and telecom infrastructure - emphasizing reliability, consistent SOA, and thermal predictability in legacy through-hole formats.

FAQ

What is the maximum allowable junction temperature for ZTX651?

The ZTX651 has a specified operating junction temperature range of –55°C to +200°C. For reliable long-term operation, maximum continuous junction temperature should be limited to 150°C per industry practice, especially when operating near its 2 A I_C and 1 W P_tot limits. Derating begins at 25°C ambient using the 5.7 mW/°C coefficient.

Can ZTX651 be used in avalanche mode?

No - the ZTX651 is not rated or characterized for controlled avalanche operation. Its absolute maximum V_CEO of 60 V applies only under standard forward-active or saturation conditions. Exceeding this voltage risks irreversible breakdown, as no avalanche energy rating (E_AS) or ruggedness data is provided in the datasheet.

Is ZTX651 RoHS compliant and halogen-free?

Yes - as part of Diodes Incorporated's post-acquisition product stewardship, the ZTX651 is manufactured to RoHS Directive 2011/65/EU requirements and is halogen-free per IEC 61249-2-21. Full compliance documentation, including material declarations and test reports, is available through Diodes' official product page and Aetrix's quality portal.

How does ZTX651's gain (h_FE) vary with collector current?

ZTX651 exhibits a typical h_FE of 100–300 at I_C = 100 mA and V_CE = 2 V, decreasing to ~60–120 at I_C = 2 A. This reduction is inherent to BJT physics and confirmed in the "h_FE v I_C" curve on page 3-221 of the datasheet - critical for designing base drive networks that maintain saturation across full load range.

ZTX651 Specifications

Product attributes: Attribute value

Manufacturer:: Diodes Incorporated

Series:: -

Package/Case:: E-Line-3

Packaging:: Bulk

Product Status:: Active

Transistor Type:: NPN

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

Voltage - Collector Emitter Breakdown (Max):: 60 V

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

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

DC Current Gain (hFE) (Min) @ Ic, Vce:: -

Power - Max:: 1 W

Frequency - Transition:: 175MHz

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

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

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

ZTX651 FAQ

1.How can I place an order for ZTX651 through Aetrix?

Please submit a Request for Quotation (RFQ) for ZTX651 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 ZTX651 reliable?

The price and inventory of ZTX651 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for ZTX651 is usually 5 days.

3.What payment methods are accepted for ZTX651?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for ZTX651 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for ZTX651?

ZTX651 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your ZTX651 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 ZTX651?

For technical support, including ZTX651 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your ZTX651 requirements.

6.How does Aetrix verify that ZTX651 is sourced from the original manufacturer or authorized distributors?

All ZTX651 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 ZTX651 meets industry standards.

7.What is the process for return or replacement of ZTX651?

All ZTX651 units undergo pre-shipment inspection (PSI). If there is an issue with ZTX651, 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 ZTX651 part is unused and in its original packaging.

Return procedure for ZTX651:

1.Submit a request within 90 days.

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

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