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

onsemi BC638TFR

Name: BC638TFR
Brand: onsemi
SKU: BC638TFR
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: BC638TFR

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

Package:: TO-226-3, TO-92-3 (TO-226AA) Formed Leads

Datasheet:: BC638TFR.pdf

Description:: TRANS PNP 60V 1A TO-92-3

Quantity:: RFQ Add To RFQ list

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Product details

Overview

BC638TFR from onsemi is a PNP epitaxial silicon transistor designed for medium-power switching and linear amplification, with −60 V V_CEO, −1 A I_C, 1 W power dissipation, h_FE = 25–160 (at I_C = −5 mA to −500 mA), and TO-92-3 package. It serves as a complement to BC637 in push-pull output stages of audio amplifiers and relay drivers.

For engineers reviewing the BC638TFR datasheet, pinout, applications, or equivalent options, key selection criteria include verified V_CEO/I_C ratings, DC current gain behavior across operating current range, saturation voltage at rated I_C/I_B, thermal resistance (125 °C/W), and Pb-free RoHS-compliant packaging per onsemi's Rev. 3 datasheet.

Technical Context

This PNP bipolar junction transistor operates in common-emitter configuration with guaranteed breakdown voltage of −60 V across V_CEO, V_CES, and V_CER conditions. Its h_FE varies from 25 at I_C = −5 mA to 40–160 at I_C = −150 mA, then drops to 25 at I_C = −500 mA - indicating optimized mid-current gain profile for switching stability.

V_CE(sat) = −0.5 V at I_C = −500 mA / I_B = −50 mA confirms low-loss conduction in saturated switch mode, while f_T = 100 MHz at V_CE = −5 V / I_C = −10 mA supports high-speed digital switching up to ~10–20 MHz practical edge rates.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	−60 V - maximum safe collector-emitter voltage before avalanche breakdown under open-base condition
I_C	−1 A - continuous DC collector current rating defining medium-power switching capability
P_D	1 W - total power dissipation at T_A = 25°C; derates 8 mW/°C above ambient
h_FE	25–160 - DC current gain range across I_C = −5 mA to −150 mA, enabling predictable base drive sizing
V_CE(sat)	−0.5 V - low saturation voltage ensures <0.25 W conduction loss at I_C = −500 mA
f_T	100 MHz - unity-gain bandwidth supporting reliable operation in 10–20 MHz switching applications
R_JA	125 °C/W - thermal resistance from junction to ambient on standard FR-4 PCB, guiding heatsinking decisions

Pinout & Package

BC638TFR is housed in TO-92-3 plastic package (Case 135AR), with standardized leadform: Emitter (pin 1), Collector (pin 2), Base (pin 3). Pin assignment follows JEDEC TO-92 outline and is marked "638" on top surface.

Pin/Terminal	Circuit Role	Design Meaning
1 (Emitter)	Current exit terminal for PNP device	Connected to most positive rail in common-emitter switch; requires low-impedance return path
2 (Collector)	Current entry terminal, controlled by base	Typically tied to load and supply rail; handles full switched current and voltage stress
3 (Base)	Control input governing transistor conduction	Driven with negative current relative to emitter; requires series resistor to limit I_B ≤ −100 mA

Key Features

Feature	Design Value
Pb-free, Halogen Free/BFR Free, RoHS compliant	Meets global environmental regulations without requiring special handling or exemptions
Complementary pairing with BC637	Enables matched NPN/PNP push-pull stages with symmetric V_CEO, I_C, and h_FE profiles
Guaranteed V_CEO = −60 V	Supports reliable operation in 48 V industrial control and 24 V automotive auxiliary circuits
1 W power rating with 125 °C/W R_JA	Allows direct mounting on standard PCBs without heatsink for ≤500 mW average dissipation

Applications

Audio Output Stage	Relay Driver
Use Scenario: Medium-power Class-B or AB audio amplifier output stage driving 8 Ω speakers. IC Role / Device Role / Timing Role: PNP switch/amplifier in complementary pair with BC637, delivering negative half-cycle current. Use Value: −60 V V_CEO and 1 W dissipation support 5–10 W RMS output into reactive loads without secondary breakdown.	Use Scenario: Driving 12 V/24 V electromagnetic relays with coil currents up to 800 mA. IC Role / Device Role / Timing Role: Saturated switch controlling relay coil ground path; base driven by microcontroller GPIO. Use Value: V_CE(sat) ≤ −0.5 V minimizes power loss and self-heating during sustained ON state.
DC Motor Control	Power Supply Sequencing
Use Scenario: Low-side switching of small brushed DC motors (e.g., fans, actuators) in embedded systems. IC Role / Device Role / Timing Role: Medium-current PNP switch enabling bidirectional control when paired with NPN counterpart. Use Value: h_FE ≥ 40 at I_C = −150 mA ensures stable saturation with ≤3.75 mA base drive - compatible with 3.3 V/5 V logic.	Use Scenario: Enabling/disabling auxiliary rails (e.g., analog sensors, RF modules) during system power-up/down sequencing. IC Role / Device Role / Timing Role: High-side or low-side enable switch activated by supervisor IC or MCU reset signal. Use Value: −5 V V_EBO and −60 V V_CEO allow safe operation across multi-rail systems with transient coupling.

Audio Output Stage

Relay Driver

Use Scenario: Medium-power Class-B or AB audio amplifier output stage driving 8 Ω speakers.

IC Role / Device Role / Timing Role: PNP switch/amplifier in complementary pair with BC637, delivering negative half-cycle current.

Use Value: −60 V V_CEO and 1 W dissipation support 5–10 W RMS output into reactive loads without secondary breakdown.

Use Scenario: Driving 12 V/24 V electromagnetic relays with coil currents up to 800 mA.

IC Role / Device Role / Timing Role: Saturated switch controlling relay coil ground path; base driven by microcontroller GPIO.

Use Value: V_CE(sat) ≤ −0.5 V minimizes power loss and self-heating during sustained ON state.

DC Motor Control

Power Supply Sequencing

Use Scenario: Low-side switching of small brushed DC motors (e.g., fans, actuators) in embedded systems.

IC Role / Device Role / Timing Role: Medium-current PNP switch enabling bidirectional control when paired with NPN counterpart.

Use Value: h_FE ≥ 40 at I_C = −150 mA ensures stable saturation with ≤3.75 mA base drive - compatible with 3.3 V/5 V logic.

Use Scenario: Enabling/disabling auxiliary rails (e.g., analog sensors, RF modules) during system power-up/down sequencing.

IC Role / Device Role / Timing Role: High-side or low-side enable switch activated by supervisor IC or MCU reset signal.

Use Value: −5 V V_EBO and −60 V V_CEO allow safe operation across multi-rail systems with transient coupling.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
BC638TA	Same die, identical electrical specs; differs only in tape-and-reel packaging (2,000 units/fan fold vs. bulk)	No functional difference; suitable for automated assembly where BC638TFR is used in manual or semi-automated lines	Select BC638TA for SMT pick-and-place; BC638TFR for prototyping or low-volume hand-soldering
MPSA92	Higher V_CEO (−300 V), lower I_C (−500 mA), smaller h_FE range (25–100); TO-92 package	Better suited for high-voltage, low-current applications (e.g., CRT deflection, HV bias supplies); not drop-in for 1 A loads	Choose MPSA92 only when >100 V blocking is required and I_C ≤ 500 mA suffices

Compared with BC638TA and MPSA92, BC638TFR offers optimal balance of 1 A current handling, −60 V rating, and gain linearity across 5–500 mA - making it preferred for general-purpose medium-power switching where cost, availability, and proven reliability in TO-92 are critical.

Availability

BC638TFR is available at Aetrix Electronics and suitable for audio amplifiers, relay drivers, DC motor controls, and power supply sequencing requiring stable component supply and long-term industrial availability.

Supply support for BC638TFR 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 focused on energy-efficient electronics, serving automotive, industrial, cloud, and IoT markets with discrete, analog, and logic solutions.

The BC638TFR belongs to onsemi's legacy bipolar transistor family engineered for robust, cost-effective medium-power linear and switching applications in consumer, industrial, and automotive subsystems.

FAQ

What is the maximum collector current rating for BC638TFR?

The BC638TFR has a continuous collector current rating (I_C) of −1 A at T_A = 25°C, with a peak collector current (I_CP) of −1.5 A. Derating applies above 25°C per the 8 mW/°C dissipation slope. This rating enables BC638TFR to reliably switch loads such as 24 V relays and small DC motors without thermal runaway under proper PCB layout.

Is BC638TFR pin-compatible with BC638TA?

Yes, BC638TFR and BC638TA share identical TO-92-3 (Case 135AR) mechanical dimensions, pinout (Emitter–Collector–Base), and full electrical specifications. The only difference is packaging format: BC638TFR is supplied in bulk or cut-tape, while BC638TA is in fan-fold tape-and-reel for automated placement. BC638TFR can be substituted for BC638TA in manual assembly without design changes.

What is the typical DC current gain (h_FE) of BC638TFR at different operating points?

Per the onsemi datasheet, BC638TFR exhibits h_FE = 25 at I_C = −5 mA, 40–160 at I_C = −150 mA, and 25 at I_C = −500 mA (all at V_CE = −2 V). This non-monotonic gain profile reflects optimized charge transport for mid-current switching - ensuring stable saturation in BC638TFR's primary use cases without excessive base drive at high loads.

Does BC638TFR support high-frequency switching applications?

BC638TFR has an f_T of 100 MHz under specified test conditions (V_CE = −5 V, I_C = −10 mA), indicating suitability for digital switching up to ~10–20 MHz with appropriate drive strength and layout. However, its 125 °C/W thermal resistance and 1 W power limit mean BC638TFR is best applied in moderate-speed, medium-current roles - not RF or ultra-high-frequency SMPS gate driving.

How does BC638TFR compare to its NPN complement BC637?

BC638TFR and BC637 form a matched complementary pair: both offer −60 V / +60 V V_CEO, ±1 A I_C, 1 W P_D, and overlapping h_FE ranges. Their symmetrical parameters enable balanced push-pull stages in BC638TFR/BC637 amplifier outputs and H-bridge drivers - minimizing crossover distortion and thermal mismatch in linear and switching applications.

BC638TFR Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

Package/Case:: TO-226-3, TO-92-3 (TO-226AA) Formed Leads

Packaging:: Tape & Reel (TR)

Product Status:: Obsolete

Transistor Type:: PNP

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

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

Vce Saturation (Max) @ Ib, Ic:: 500mV @ 50mA, 500mA

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

DC Current Gain (hFE) (Min) @ Ic, Vce:: 40 @ 150mA, 2V

Power - Max:: 1 W

Frequency - Transition:: 100MHz

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-92-3

BC638TFR FAQ

1.How can I place an order for BC638TFR through Aetrix?

Please submit a Request for Quotation (RFQ) for BC638TFR 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 BC638TFR reliable?

The price and inventory of BC638TFR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BC638TFR is usually 5 days.

3.What payment methods are accepted for BC638TFR?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BC638TFR transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for BC638TFR?

BC638TFR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your BC638TFR 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 BC638TFR?

For technical support, including BC638TFR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BC638TFR requirements.

6.How does Aetrix verify that BC638TFR is sourced from the original manufacturer or authorized distributors?

All BC638TFR 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 BC638TFR meets industry standards.

7.What is the process for return or replacement of BC638TFR?

All BC638TFR units undergo pre-shipment inspection (PSI). If there is an issue with BC638TFR, 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 BC638TFR part is unused and in its original packaging.

Return procedure for BC638TFR:

1.Submit a request within 90 days.

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

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