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NXP Semiconductors BC638,126
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- Part No.:
- BC638,126
- Manufacturer:
- NXP Semiconductors
- Category:
- Single Bipolar Transistors
- Package:
- TO-226-3, TO-92-3 (TO-226AA) Formed Leads
- Datasheet:
-
BC638,126.pdf
- Description:
- TRANS PNP 60V 1A TO-92-3
- Quantity:
- Payment:
- Shipping:
Inventory:3,547
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Product details
Overview
BC638,126 from Nexperia (formerly Philips Semiconductors) is a PNP medium-power bipolar junction transistor in TO-92 (SOT54) package, rated for −60 V collector-base voltage, −60 V collector-emitter voltage, and −1 A DC collector current. It serves as a general-purpose switching and linear amplification device in audio output stages and power control circuits.
For engineers reviewing the BC638,126 datasheet, BC638,126 pinout, BC638,126 application, or BC638,126 equivalent, key selection criteria include its PNP polarity, 0.83 W power dissipation at 25 °C ambient, 150 K/W junction-to-ambient thermal resistance, and verified DC current gain of 63–250 at IC = −150 mA.
Technical Context
The BC638,126 operates as a silicon PNP BJT with fixed emitter-base and collector-base junction structures optimized for medium-power analog and switching use. Its hFE exhibits strong current dependency-minimum 63 at IC = −5 mA and −150 mA, dropping to 40 at −500 mA-supporting stable biasing across mid-range load currents.
It features low saturation voltage (VCEsat ≤ −0.5 V at IC = −500 mA/IB = −50 mA) and base-emitter forward voltage of up to −1 V, enabling efficient drive in Class-A/B amplifier output stages and relay driver circuits where low conduction loss and predictable turn-on threshold are required.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Collector-emitter voltage (VCEO) | −60 V - supports operation in 48 V rail systems with safety margin |
| DC current gain (hFE) | 63–250 at IC = −150 mA - enables stable bias design without excessive base drive |
| Collector current (IC) | −1 A continuous - suitable for driving small speakers, solenoids, or LED arrays |
| Power dissipation (Ptot) | 0.83 W at Tamb ≤ 25 °C - requires heatsinking or derating above ambient 25 °C |
| Thermal resistance (Rth(j-a)) | 150 K/W - limits junction temperature rise to ~125 K per watt on FR4 PCB |
| Transition frequency (fT) | 100 MHz - sufficient for audio band amplification and low-speed switching (<10 MHz) |
Pinout & Package
BC638,126 is housed in a plastic single-ended leaded (through-hole) TO-92 package, also designated SOT54 or SC-43A, with 3 leads and standard 2.54 mm lead pitch.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | Base | Control terminal; accepts negative base current to enable conduction between collector and emitter |
| 2 | Collector | Main current sink terminal; connected to higher potential (e.g., VCC rail) in PNP configuration |
| 3 | Emitter | Current source terminal; typically tied to ground or load return path in common-emitter switch |
Key Features
| Feature | Design Value |
|---|---|
| High DC current capability | Rated −1 A continuous collector current supports robust load switching without secondary breakdown |
| Low saturation voltage | VCEsat ≤ −0.5 V at IC = −500 mA ensures < 250 mW conduction loss in saturated switch mode |
| Stable hFE over operating range | Minimum hFE = 63 at both IC = −5 mA and −150 mA simplifies bias network design |
| TO-92 mechanical compatibility | SOT54 outline meets JEDEC TO-92 standards for automated insertion and board-level reliability |
Applications
| Audio Power Amplifier Output Stage | DC Motor Direction Control |
|---|---|
Use Scenario: Driving 8 Ω speaker loads in Class-B push-pull output pairs with complementary NPN BC637. IC Role / Device Role / Timing Role: PNP switching element providing current sink capability during negative half-cycle amplification. Use Value: −60 V VCEO and 0.83 W Ptot allow safe operation at ±24 V rails with thermal headroom on standard FR4 PCB. | Use Scenario: H-bridge half-bridge leg controlling bidirectional 12 V DC motor current up to 800 mA. IC Role / Device Role / Timing Role: High-side PNP switch enabling grounded-load motor control topology. Use Value: Low VCEsat (≤ −0.5 V) minimizes power loss and heat generation during sustained conduction. |
| Relay Driver Circuit | Linear Voltage Regulator Pass Element |
Use Scenario: Switching 24 V/40 mA electromagnetic relay coils using microcontroller GPIO via base resistor. IC Role / Device Role / Timing Role: Medium-current interface transistor translating logic-level signals to coil drive capability. Use Value: hFE ≥ 63 at low IC ensures reliable saturation with ≤ 1 mA base drive, reducing MCU I/O loading. | Use Scenario: Series pass transistor in adjustable 5–15 V linear regulator supplying 500 mA to analog sensor circuitry. IC Role / Device Role / Timing Role: Current-controlled series regulator element dissipating excess input-output differential voltage. Use Value: 150 K/W Rth(j-a) allows ~12 °C/W effective thermal resistance with minimal copper pour, supporting 3 W dissipation with 40 °C rise. |
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 |
|---|---|---|---|
| BC638-16 | Same die, binned for hFE = 100–250 (vs. BC638,126's unspecified hFE grade) | Preferred where tighter hFE consistency is required for matched pair designs | Select BC638-16 when designing complementary amplifier stages requiring hFE symmetry with BC637-16 |
| MJD127G | TO-220 package, −100 V VCEO, −1.5 A IC, higher Ptot (1.5 W), no TO-92 footprint | Suitable for higher-power or surface-mount alternatives requiring thermal upgrade | Choose MJD127G only if board layout allows TO-220 mounting and thermal management supports >1 W dissipation |
Compared with BC638-16, BC638,126 offers broader hFE distribution but identical voltage/current ratings and TO-92 form factor; versus MJD127G, it trades higher power handling and voltage rating for through-hole compatibility and lower cost in low-to-mid power applications.
Availability
BC638,126 is available at Aetrix Electronics and suitable for audio amplifier design, relay interface development, and linear regulator prototyping requiring stable component supply and long-term industrial availability.
Supply support for BC638,126 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
Nexperia is a global semiconductor expert delivering high-performance, reliable discrete, logic, and MOSFET solutions, spun off from Philips Semiconductors in 2017.
The BC638,126 belongs to Nexperia's legacy general-purpose bipolar transistor family, designed for cost-sensitive, medium-power linear and switching applications in consumer, industrial, and automotive-qualified systems.
FAQ
What is the maximum collector-emitter voltage rating for BC638,126?
The BC638,126 has a maximum collector-emitter voltage (VCEO) rating of −60 V under open-base conditions. This rating is absolute and must not be exceeded even momentarily, as stress beyond this limit may cause permanent device failure. The BC638,126 datasheet confirms this value applies specifically to the BC638 variant, distinguishing it from BC636 (−45 V) and BC640 (−80 V).
Is BC638,126 pin-compatible with BC637 or other complementary transistors?
Yes, BC638,126 shares the same TO-92 (SOT54) package and pinout (base-collector-emitter at pins 1–2–3) as its NPN complement BC637, enabling direct placement in push-pull amplifier configurations. However, polarity reversal means external biasing networks must be adapted accordingly-BC638,126 requires negative base current relative to emitter.
What is the typical DC current gain (hFE) of BC638,126 at 150 mA collector current?
At VCE = −2 V and IC = −150 mA, the BC638,126 exhibits a DC current gain (hFE) ranging from 63 to 250. This wide span reflects standard production binning; the BC638-16 variant is specifically binned to 100–250, while BC638,126 carries no hFE suffix and conforms to the full family specification.
Can BC638,126 be used in surface-mount designs?
No, BC638,126 is a through-hole device in TO-92 (SOT54) package and is not suitable for surface-mount assembly. For SMT equivalents, consider devices like PBSS4240T (SOT23) or ZTX951 (SOT89), though these differ in voltage, current, and thermal performance-direct replacement requires redesign verification.
What is the thermal resistance from junction to ambient for BC638,126?
The BC638,126 has a thermal resistance from junction to ambient (Rth(j-a)) of 150 K/W when mounted on a standard FR4 printed-circuit board, as specified in the Philips/Nexperia datasheet. This value assumes no added copper pour or heatsinking; actual thermal performance improves with increased PCB copper area connected to the collector lead.
BC638,126 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- NXP Semiconductors
- Series:
- -
- Package/Case:
- TO-226-3, TO-92-3 (TO-226AA) Formed Leads
- Packaging:
- Tape & Box (TB)
- 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:
- 63 @ 150mA, 2V
- Power - Max:
- 830 mW
- Frequency - Transition:
- 100MHz
- Operating Temperature:
- 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- TO-92-3
BC638,126 FAQ
1.How can I place an order for BC638,126 through Aetrix?
Please submit a Request for Quotation (RFQ) for BC638,126 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 BC638,126 reliable?
The price and inventory of BC638,126 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BC638,126 is usually 5 days.
3.What payment methods are accepted for BC638,126?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BC638,126 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for BC638,126?
BC638,126 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your BC638,126 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 BC638,126?
For technical support, including BC638,126 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BC638,126 requirements.
6.How does Aetrix verify that BC638,126 is sourced from the original manufacturer or authorized distributors?
All BC638,126 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 BC638,126 meets industry standards.
7.What is the process for return or replacement of BC638,126?
All BC638,126 units undergo pre-shipment inspection (PSI). If there is an issue with BC638,126, 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 BC638,126 part is unused and in its original packaging.
Return procedure for BC638,126:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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