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

onsemi TIP42B

Name: TIP42B
Brand: onsemi
SKU: TIP42B
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: TIP42B

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

Package:: TO-220-3

Datasheet:: TIP42B.pdf

Description:: TRANS PNP 80V 6A TO-220

Quantity:: RFQ Add To RFQ list

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Product details

Overview

TIP42B from onsemi is a PNP epitaxial silicon power transistor in TO-220 package, rated for -40 V V_CEO, -6 A I_C (DC), 65 W P_C at T_C = 25°C, and h_FE ≥ 30 at I_C = -0.3 A; used in medium-power linear regulators and switching circuits such as audio amplifier output stages and DC motor drivers.

For engineers reviewing the TIP42B datasheet, pinout, applications, or equivalent options, key selection criteria include verified PNP polarity, TO-220 thermal performance, V_CEO = -40 V rating, h_FE consistency across I_C = -0.3 A to -3 A, and safe operating area compliance per Figure 3 in the official datasheet.

Technical Context

The TIP42B operates as a medium-power PNP bipolar junction transistor with epitaxial base construction, supporting both linear amplification and hard-switching modes. Its V_CEO(sus) = -40 V and I_C = -6 A DC rating define its use in non-isolated, low-to-medium voltage power control circuits.

Thermal design relies on case-mounted heatsinking: P_C derates linearly above 25°C case temperature, reaching zero at 175°C. The device exhibits f_T = 3.0 MHz at V_CE = -10 V and I_C = -500 mA, confirming suitability for audio-frequency switching but not RF applications.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	-40 V - Maximum collector-emitter blocking voltage before breakdown; sets upper limit for supply rail in PNP high-side switch designs.
I_C (DC)	-6 A - Continuous collector current capability; determines maximum load drive in linear regulators or motor H-bridge legs.
P_C (T_C = 25°C)	65 W - Steady-state power dissipation at case temperature 25°C; requires heatsink sizing per thermal resistance curve in Figure 4.
h_FE	30–75 - DC current gain range at V_CE = -4 V; enables predictable base drive calculation for saturation in switching applications.
V_CE(sat)	-1.5 V @ I_C = -6 A, I_B = -600 mA - Confirmed saturation voltage; defines conduction loss and thermal load under full-load switching.
f_T	3.0 MHz - Current gain bandwidth product; validates usable frequency range up to ~100 kHz for PWM-driven loads without significant gain roll-off.

Pinout & Package

Package: TO-220 3L (Single Gauge), through-hole, case-connected to collector; requires mechanical mounting to heatsink with electrically isolated hardware if collector is not at ground potential.

Pin/Terminal	Circuit Role	Design Meaning
1 (Left, when face up, tab up)	Base	Control terminal; accepts negative current to turn on; requires series resistor to limit I_B ≤ -2 A peak.
2 (Center)	Collector	Main current path input; electrically tied to metal tab; must be insulated from heatsink unless circuit common reference.
3 (Right)	Emitter	Current source output; connects to positive supply rail in high-side switch configuration.

Key Features

Feature	Design Value
Medium-power linear/switching operation	Validated by 65 W P_C and SOA curve (Figure 3) supporting continuous DC and pulsed loads up to 10 A.
Complementary pairing with TIP41 series	Enables push-pull and Class AB amplifier topologies using matched PNP/NPN characteristics and TO-220 footprint.
Epitaxial silicon construction	Provides stable h_FE and low leakage (I_CEO ≤ -0.7 mA) across temperature, critical for bias stability in analog circuits.
JEDEC-standard TO-220 package	Ensures mechanical compatibility with industry-standard heatsinks and PCB footprints; tab serves as collector and thermal path.

Applications

Audio Power Amplifier Output Stage	DC Motor Driver (High-Side)
Use Scenario: Driving 4–8 Ω speaker loads in Class AB amplifier output stage with complementary NPN/PNP pair. IC Role / Device Role / Timing Role: PNP power switch providing current sink capability during negative half-cycle of audio waveform. Use Value: V_CEO = -40 V and h_FE ≥ 30 ensure clean crossover and low distortion at 1–20 kHz; TO-220 thermal mass stabilizes bias under dynamic load.	Use Scenario: Controlling brushed DC motor direction and speed via high-side PNP switch in H-bridge or single-ended driver. IC Role / Device Role / Timing Role: High-side current source enabling ground-referenced motor return path and simplified gate drive logic. Use Value: I_C = -6 A and V_CE(sat) = -1.5 V minimize conduction loss and heat generation at 12–24 V supply rails.
Linear Voltage Regulator Pass Element	Relay/LED Driver Interface
Use Scenario: Series pass transistor in adjustable linear regulator delivering up to 5 A at ≤ 35 V dropout. IC Role / Device Role / Timing Role: Adjustable current source regulating output voltage via feedback-controlled base current. Use Value: P_C = 65 W and SOA compliance allow stable operation under worst-case dropout (e.g., 35 V × 5 A = 175 W transient) with proper heatsinking.	Use Scenario: Switching 12 V/24 V industrial relays or high-brightness LED strings requiring >2 A load current. IC Role / Device Role / Timing Role: Saturated PNP switch interfacing microcontroller GPIO to higher-voltage, higher-current loads. Use Value: Verified V_BE(on) = -2.0 V at I_C = -6 A ensures reliable turn-on with standard 5 V or 3.3 V logic-level base drive via current-limiting resistor.

Audio Power Amplifier Output Stage

DC Motor Driver (High-Side)

Use Scenario: Driving 4–8 Ω speaker loads in Class AB amplifier output stage with complementary NPN/PNP pair.

IC Role / Device Role / Timing Role: PNP power switch providing current sink capability during negative half-cycle of audio waveform.

Use Value: V_CEO = -40 V and h_FE ≥ 30 ensure clean crossover and low distortion at 1–20 kHz; TO-220 thermal mass stabilizes bias under dynamic load.

Use Scenario: Controlling brushed DC motor direction and speed via high-side PNP switch in H-bridge or single-ended driver.

IC Role / Device Role / Timing Role: High-side current source enabling ground-referenced motor return path and simplified gate drive logic.

Use Value: I_C = -6 A and V_CE(sat) = -1.5 V minimize conduction loss and heat generation at 12–24 V supply rails.

Linear Voltage Regulator Pass Element

Relay/LED Driver Interface

Use Scenario: Series pass transistor in adjustable linear regulator delivering up to 5 A at ≤ 35 V dropout.

IC Role / Device Role / Timing Role: Adjustable current source regulating output voltage via feedback-controlled base current.

Use Value: P_C = 65 W and SOA compliance allow stable operation under worst-case dropout (e.g., 35 V × 5 A = 175 W transient) with proper heatsinking.

Use Scenario: Switching 12 V/24 V industrial relays or high-brightness LED strings requiring >2 A load current.

IC Role / Device Role / Timing Role: Saturated PNP switch interfacing microcontroller GPIO to higher-voltage, higher-current loads.

Use Value: Verified V_BE(on) = -2.0 V at I_C = -6 A ensures reliable turn-on with standard 5 V or 3.3 V logic-level base drive via current-limiting resistor.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
MJD42C	TO-252 (DPAK) surface-mount package; same V_CEO = -100 V, but lower P_C = 20 W at T_A.	Not suitable for through-hole prototyping or high-power heatsink mounting; limited to PCB-constrained thermal management.	Select MJD42C only for space-constrained SMT designs where <20 W dissipation is acceptable.
TIP42C	Same TO-220 package and pinout; higher V_CEO = -100 V and identical I_C/P_C/h_FE specs except breakdown rating.	Direct drop-in replacement where higher voltage margin is required; no change to layout or drive network.	Choose TIP42C when system bus voltage exceeds 40 V or long-term reliability demands wider voltage safety margin.

Compared with MJD42C, TIP42B offers superior thermal handling via TO-220 and higher absolute power capability; versus TIP42C, it trades voltage headroom for cost-sensitive 40 V applications without sacrificing pin compatibility or drive requirements.

Availability

TIP42B is available at Aetrix Electronics and suitable for audio amplifier output stages, DC motor drivers, linear voltage regulator pass elements, and relay/LED interface circuits requiring stable component supply and proven thermal performance in TO-220 format.

Supply support for TIP42B 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

onsemi (formerly ON Semiconductor) is a global semiconductor supplier specializing in energy-efficient power, analog, sensor, and connectivity solutions for automotive, industrial, cloud, and IoT applications.

The TIP42B belongs to the legacy TIP41/TIP42 family of general-purpose power transistors designed for cost-effective, robust medium-power linear and switching applications in consumer, industrial, and educational electronics.

FAQ

What is the maximum collector-emitter voltage rating for TIP42B?

The TIP42B has a maximum collector-emitter sustaining voltage V_CEO(sus) of -40 V at I_C = -30 mA and I_B = 0, as specified in the onsemi datasheet. This rating defines the upper limit for safe DC blocking in high-side switch or linear regulator configurations. Exceeding this voltage risks avalanche breakdown and permanent device failure. Designers must maintain at least 20% margin below -40 V in production systems.

Is TIP42B pin-compatible with TIP42C?

Yes, TIP42B is pin-compatible with TIP42C - both use identical TO-220 3L package with Base/Collector/Emitter pinout (1/2/3). However, TIP42C is rated for -100 V V_CEO, while TIP42B is rated for -40 V. No PCB changes are needed when substituting TIP42C for TIP42B, but the reverse may compromise voltage safety in higher-rail applications.

What is the typical DC current gain (h_FE) of TIP42B at different operating points?

The TIP42B exhibits h_FE = 30 (min) at V_CE = -4 V and I_C = -0.3 A, and h_FE = 15 (min) at V_CE = -4 V and I_C = -3 A, per the onsemi datasheet. This gain compression at higher current informs base drive design: for 6 A load, ≥600 mA base current is required to ensure saturation, confirmed by V_CE(sat) = -1.5 V test condition.

Can TIP42B be used in switching power supplies?

TIP42B supports switching operation up to ~100 kHz due to its f_T = 3.0 MHz, but it is not optimized for high-frequency SMPS. Its relatively high V_CE(sat) (-1.5 V) and slow storage time (not specified in datasheet) limit efficiency above 20 kHz. It remains appropriate for low-frequency PWM motor control or line-frequency inverters where thermal robustness outweighs switching speed.

What thermal considerations apply when using TIP42B in continuous operation?

TIP42B dissipates up to 65 W at T_C = 25°C, but power rating drops linearly with case temperature - zero at 175°C (Figure 4). For continuous 30 W operation, a heatsink with θ_JA ≤ 2.5°C/W is required assuming 25°C ambient. Mounting must electrically isolate the collector-tab unless referenced to system ground, and thermal interface material must minimize contact resistance to sustain junction temperature ≤ 150°C.

TIP42B Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

Package/Case:: TO-220-3

Packaging:: Tube

Product Status:: Obsolete

Transistor Type:: PNP

Current - Collector (Ic) (Max):: 6 A

Voltage - Collector Emitter Breakdown (Max):: 80 V

Vce Saturation (Max) @ Ib, Ic:: 1.5V @ 600mA, 6A

Current - Collector Cutoff (Max):: 700µA

DC Current Gain (hFE) (Min) @ Ic, Vce:: 15 @ 3A, 4V

Power - Max:: 2 W

Frequency - Transition:: 3MHz

Operating Temperature:: -65°C ~ 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-220

TIP42B FAQ

1.How can I place an order for TIP42B through Aetrix?

Please submit a Request for Quotation (RFQ) for TIP42B 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 TIP42B reliable?

The price and inventory of TIP42B are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for TIP42B is usually 5 days.

3.What payment methods are accepted for TIP42B?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for TIP42B transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for TIP42B?

TIP42B orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your TIP42B 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 TIP42B?

For technical support, including TIP42B datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your TIP42B requirements.

6.How does Aetrix verify that TIP42B is sourced from the original manufacturer or authorized distributors?

All TIP42B 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 TIP42B meets industry standards.

7.What is the process for return or replacement of TIP42B?

All TIP42B units undergo pre-shipment inspection (PSI). If there is an issue with TIP42B, 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 TIP42B part is unused and in its original packaging.

Return procedure for TIP42B:

1.Submit a request within 90 days.

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

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