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

onsemi PZTA42T1

Name: PZTA42T1
Brand: onsemi
SKU: PZTA42T1
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: PZTA42T1

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

Package:: TO-261-4, TO-261AA

Datasheet:: PZTA42T1.pdf

Description:: TRANS NPN 300V 0.5A SOT223

Quantity:: RFQ Add To RFQ list

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Product details

Overview

PZTA42T1 from ON Semiconductor is an NPN silicon high-voltage transistor in SOT-223 package, rated for 300 V_CEO, 500 mA DC collector current, and 1.5 W power dissipation at 25°C ambient. It delivers h_FE ≥25 at 1 mA, f_T = 50 MHz, and V_CE(sat) ≤ 0.5 V at I_C/I_B = 10 - used in high-voltage switching and interface driver circuits for industrial controls and power supply feedback stages.

For engineers reviewing the PZTA42T1 datasheet, pinout, applications, or equivalent options, key selection criteria include its 300 V breakdown rating, SOT-223 thermal performance (R_θJA = 83.3°C/W), saturation voltage behavior across temperature, and compatibility with standard surface-mount reflow profiles.

Technical Context

The PZTA42T1 is a discrete NPN bipolar junction transistor optimized for high-voltage linear and switching operation up to 300 V. Its design supports stable DC current gain (h_FE = 25–40) across collector currents from 1 mA to 30 mA and maintains low leakage (I_CBO, I_EBO ≤ 0.1 µA) under rated reverse bias conditions.

Thermal performance is defined for mounting on a 1.575″ × 1.575″ glass-epoxy PCB with ≥0.93 in² collector pad area. Dynamic characteristics include f_T = 50 MHz at I_C = 10 mA and C_re ≤ 3.0 pF, enabling use in medium-frequency amplifier and pulse driver applications.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	300 V - supports direct switching of 240 VAC-derived rails or flyback snubber circuits without external clamping.
I_C (DC)	500 mA - sufficient for driving small relays, optocoupler LEDs, or gate resistors in MOSFET/IGBT interface stages.
P_D @ 25°C	1.5 W - achievable with minimum recommended SOT-223 footprint on FR4; requires thermal pad design for sustained >500 mW operation.
h_FE	25–40 - enables reliable base-current-limited switching with predictable drive requirements across 1–30 mA I_C.
f_T	50 MHz - suitable for <10 MHz pulse amplification and fast-switching applications such as PWM signal buffering.
V_CE(sat)	≤0.5 V @ I_C/I_B = 10 - minimizes conduction loss in saturated-switch mode, critical for efficiency in low-duty-cycle drivers.

Pinout & Package

SOT-223 (TO-261AA) package with exposed collector tab (pins 2 and 4 electrically common); thermally enhanced for surface-mount power dissipation. Mounting requires ≥0.93 in² copper area on collector pad to achieve rated 1.5 W.

Pin/Terminal	Circuit Role	Design Meaning
1	Base	Control input requiring ~2 mA base drive for 20 mA collector saturation; referenced to emitter for standard common-emitter configuration.
2 & 4	Collector	High-voltage output node; electrically tied together and thermally connected to exposed pad - must be routed to largest available ground/power plane for thermal management.
3	Emitter	Reference terminal for bias network; typically tied to circuit ground or low-side return path in switching topologies.

Key Features

Feature	Design Value
300 V V_CEO rating	Enables direct interface with off-line AC/DC auxiliary supplies and industrial 24–48 V control buses without series resistors or voltage dividers.
SOT-223 thermal performance	R_θJA = 83.3°C/W with standard footprint - allows 1.5 W dissipation at +25°C ambient, supporting compact high-voltage driver designs.
Low leakage (I_CBO, I_EBO ≤ 0.1 µA)	Ensures stable cutoff state in high-impedance bias networks and prevents false triggering in precision timing or sensing interfaces.
V_BE(sat) ≤ 0.9 V	Reduces base drive power loss and simplifies logic-level compatibility with 3.3 V or 5 V microcontroller outputs.

Applications

Industrial Relay Drivers	AC/DC Power Supply Feedback
Use Scenario: Driving 12–24 VDC coil relays in PLC I/O modules and motor starter panels where input isolation and 300 V transient immunity are required. IC Role / Device Role / Timing Role: Discrete NPN switch providing galvanic isolation interface between low-voltage logic and high-energy relay coils. Use Value: Withstands 300 V transients during relay coil de-energization and delivers <0.5 V saturation drop to minimize heat generation at 500 mA peak load.	Use Scenario: Amplifying optocoupler output signals in isolated flyback and forward converter feedback loops operating at 24–48 V output. IC Role / Device Role / Timing Role: High-voltage level-shifting transistor translating secondary-side error voltage to primary-side PWM controller reference. Use Value: 300 V V_CEO rating ensures safe operation across full output range including line surges; h_FE stability supports accurate error signal gain over temperature.
High-Voltage Interface Buffers	Linear Voltage Regulator Pass Elements
Use Scenario: Buffering TTL/CMOS signals to drive 100–200 V loads in test equipment, lamp dimmers, and solenoid controllers. IC Role / Device Role / Timing Role: Medium-speed voltage translator and current booster stage interfacing digital logic with high-voltage analog subsystems. Use Value: 50 MHz f_T and ≤3.0 pF C_re support clean edge integrity up to 5 MHz; low V_CE(sat) preserves signal headroom in active-high configurations.	Use Scenario: Serving as pass transistor in adjustable linear regulators delivering 12–36 V outputs from unregulated 48–300 V DC inputs. IC Role / Device Role / Timing Role: Series-pass element regulating output voltage via base-controlled emitter-follower configuration. Use Value: Junction temperature limit of 150°C and R_θJA = 83.3°C/W enable continuous operation at 1.2 W dissipation when properly heatsinked on PCB.

Industrial Relay Drivers

AC/DC Power Supply Feedback

Use Scenario: Driving 12–24 VDC coil relays in PLC I/O modules and motor starter panels where input isolation and 300 V transient immunity are required.

IC Role / Device Role / Timing Role: Discrete NPN switch providing galvanic isolation interface between low-voltage logic and high-energy relay coils.

Use Value: Withstands 300 V transients during relay coil de-energization and delivers <0.5 V saturation drop to minimize heat generation at 500 mA peak load.

Use Scenario: Amplifying optocoupler output signals in isolated flyback and forward converter feedback loops operating at 24–48 V output.

IC Role / Device Role / Timing Role: High-voltage level-shifting transistor translating secondary-side error voltage to primary-side PWM controller reference.

Use Value: 300 V V_CEO rating ensures safe operation across full output range including line surges; h_FE stability supports accurate error signal gain over temperature.

High-Voltage Interface Buffers

Linear Voltage Regulator Pass Elements

Use Scenario: Buffering TTL/CMOS signals to drive 100–200 V loads in test equipment, lamp dimmers, and solenoid controllers.

IC Role / Device Role / Timing Role: Medium-speed voltage translator and current booster stage interfacing digital logic with high-voltage analog subsystems.

Use Value: 50 MHz f_T and ≤3.0 pF C_re support clean edge integrity up to 5 MHz; low V_CE(sat) preserves signal headroom in active-high configurations.

Use Scenario: Serving as pass transistor in adjustable linear regulators delivering 12–36 V outputs from unregulated 48–300 V DC inputs.

IC Role / Device Role / Timing Role: Series-pass element regulating output voltage via base-controlled emitter-follower configuration.

Use Value: Junction temperature limit of 150°C and R_θJA = 83.3°C/W enable continuous operation at 1.2 W dissipation when properly heatsinked on PCB.

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-voltage NPN transistor applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
MPSA42	TO-92 package, R_θJA ≈ 200°C/W, same 300 V/500 mA ratings but lower power capability (0.625 W).	Limited to low-power signal switching; unsuitable for sustained >300 mW dissipation without external heatsinking.	Select MPSA42 only for space-constrained prototyping or low-duty-cycle signal routing where thermal mass is not limiting.
ZTX653	SOT-89 package, V_CEO = 300 V, I_C = 1 A, P_D = 2.5 W, h_FE = 100–300 - higher gain and power, but larger footprint and different pinout.	Supports higher current and better thermal margin; requires PCB layout revision due to 3-pin SOT-89 vs. 4-pin SOT-223.	Choose ZTX653 when >500 mA peak load or improved thermal headroom is required, accepting board redesign effort.

Compared with MPSA42, the PZTA42T1 offers 2.4× higher power dissipation in surface-mount form; versus ZTX653, it provides identical voltage rating with smaller footprint and lower cost, though at reduced current gain and maximum current capacity.

Availability

PZTA42T1 is available at Aetrix Electronics and suitable for industrial relay drivers, AC/DC power supply feedback circuits, and high-voltage interface buffers requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for PZTA42T1 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

ON Semiconductor is a global supplier of energy-efficient semiconductor components, specializing in power management, analog, sensor, and discrete devices for automotive, industrial, and consumer markets.

The PZTA42T1 belongs to ON Semiconductor's high-voltage bipolar transistor product line, designed specifically for robust switching and amplification in off-line power systems and industrial control interfaces.

FAQ

What is the maximum collector-emitter voltage rating for the PZTA42T1?

The PZTA42T1 has a maximum collector-emitter voltage (V_CEO) rating of 300 VDC under open-base conditions. This rating is verified per JEDEC test conditions (I_C = 1.0 mA, T_A = 25°C) and defines the absolute upper limit for safe operation in blocking or switching modes. Exceeding this voltage risks avalanche breakdown and permanent device failure.

Can the PZTA42T1 be used in linear regulator applications?

Yes, the PZTA42T1 can serve as a pass transistor in adjustable linear regulators, particularly where input-to-output differential exceeds 40 V. Its 300 V V_CEO rating, 150°C junction temperature limit, and SOT-223 thermal profile support continuous operation at up to 1.2 W dissipation when mounted per ON Semiconductor's recommended footprint - making it viable for medium-power, high-input-voltage LDO designs.

What is the thermal resistance (R_θJA) of the PZTA42T1 and how is it achieved?

The PZTA42T1 has a specified R_θJA of 83.3°C/W when mounted on a 1.575″ × 1.575″ glass-epoxy PCB with a minimum 0.93 in² copper area connected to pins 2 and 4 (collector). This value assumes standard JEDEC test board construction and is validated by ON Semiconductor's thermal characterization - achieving full 1.5 W power dissipation at 25°C ambient.

Does the PZTA42T1 have a documented current-gain bandwidth product (f_T)?

Yes, the PZTA42T1 has a guaranteed minimum f_T of 50 MHz, measured at I_C = 10 mA, V_CE = 20 V, and f = 100 MHz. This parameter confirms suitability for medium-frequency amplification and fast-switching applications such as PWM signal buffering and pulse shaping circuits where bandwidth up to 10 MHz is required.

How many pins does the PZTA42T1 have and what is their functional assignment?

The PZTA42T1 uses a 4-pin SOT-223 package: Pin 1 is Base, Pins 2 and 4 are electrically common Collector terminals (with thermal pad connection), and Pin 3 is Emitter. This dual-collector configuration enhances thermal conduction and current handling - critical for reliability in high-voltage switching applications using the PZTA42T1.

PZTA42T1 Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

Package/Case:: TO-261-4, TO-261AA

Packaging:: Cut Tape (CT)

Product Status:: Obsolete

Transistor Type:: NPN

Current - Collector (Ic) (Max):: 500 mA

Voltage - Collector Emitter Breakdown (Max):: 300 V

Vce Saturation (Max) @ Ib, Ic:: 500mV @ 2mA, 20mA

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

DC Current Gain (hFE) (Min) @ Ic, Vce:: 40 @ 30mA, 10V

Power - Max:: 1.5 W

Frequency - Transition:: 50MHz

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: SOT-223 (TO-261)

PZTA42T1 FAQ

1.How can I place an order for PZTA42T1 through Aetrix?

Please submit a Request for Quotation (RFQ) for PZTA42T1 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 PZTA42T1 reliable?

The price and inventory of PZTA42T1 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for PZTA42T1 is usually 5 days.

3.What payment methods are accepted for PZTA42T1?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for PZTA42T1 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for PZTA42T1?

PZTA42T1 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your PZTA42T1 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 PZTA42T1?

For technical support, including PZTA42T1 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your PZTA42T1 requirements.

6.How does Aetrix verify that PZTA42T1 is sourced from the original manufacturer or authorized distributors?

All PZTA42T1 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 PZTA42T1 meets industry standards.

7.What is the process for return or replacement of PZTA42T1?

All PZTA42T1 units undergo pre-shipment inspection (PSI). If there is an issue with PZTA42T1, 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 PZTA42T1 part is unused and in its original packaging.

Return procedure for PZTA42T1:

1.Submit a request within 90 days.

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

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