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

onsemi BC557BTAR

Name: BC557BTAR
Brand: onsemi
SKU: BC557BTAR
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: BC557BTAR

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

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

Datasheet:: BC557BTAR.pdf

Description:: TRANS PNP 45V 0.1A TO-92-3

Quantity:: RFQ Add To RFQ list

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Inventory:5,900

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Product details

Overview

BC557BTAR from onsemi is a PNP epitaxial silicon transistor designed for general-purpose switching and linear amplification in low-power analog and digital circuits. It features V_CEO = −45 V, I_C = −100 mA, h_FE = 200–450 (Class B), V_CE(sat) ≤ −300 mV at I_C = −10 mA/I_B = −0.5 mA, and f_T = 150 MHz - enabling use in audio preamplifiers, level shifters, and discrete logic interfaces.

For engineers reviewing the BC557BTAR datasheet, pinout, applications, or equivalent options, key selection criteria include its TO-92-3 (Case 135AR) package, complementary pairing with BC547/BC548 NPN transistors, low-noise capability (NF = 2–10 dB), and RoHS-compliant Pb-free construction.

Technical Context

The BC557BTAR operates as a medium-voltage, medium-current PNP bipolar junction transistor optimized for DC-coupled amplification and saturated switching. Its h_FE classification (B-grade: 200–450) ensures predictable current gain across production lots, while its −45 V V_CEO rating supports operation in rail-to-rail negative supply configurations up to ±45 V systems.

Thermal performance is defined by R_JA = 250 °C/W (FR-4 PCB, 76 mm × 114 mm), PD = 500 mW at 25°C with 4.0 mW/°C derating - confirming suitability for continuous operation in ambient temperatures up to +125°C when power dissipation remains below 300 mW.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	−45 V: Maximum collector-emitter voltage before breakdown; enables use in −45 V rail systems or high-side switch applications.
I_C (DC)	−100 mA: Continuous collector current handling; sufficient for driving LEDs, small relays, or biasing other transistors.
h_FE (B-grade)	200–450 @ V_CE = −5 V, I_C = −2 mA: Tight DC current gain spread improves predictability in amplifier bias networks.
V_CE(sat)	≤ −300 mV @ I_C = −10 mA / I_B = −0.5 mA: Low saturation voltage minimizes power loss in switching applications.
f_T	150 MHz @ V_CE = −5 V, I_C = −10 mA: Supports audio-frequency amplification and fast digital signal conditioning.
NF	2–10 dB @ 1 kHz, I_C = −200 µA: Confirmed low-noise performance for sensitive preamp stages.

Pinout & Package

BC557BTAR is housed in a TO-92-3 plastic package (Case 135AR), lead-formed for through-hole mounting. Dimensions: 4.83 mm × 4.76 mm × 3.6 mm. Marking: "BC557B".

Pin/Terminal	Circuit Role	Design Meaning
1 (Top View, Flat Side Up)	Collector	Main current sink terminal; connects to most negative potential in PNP configuration.
2	Base	Control input; requires negative base current relative to emitter to turn on device.
3	Emitter	Current source terminal; typically tied to system ground or positive rail in common-emitter topology.

Key Features

Feature	Design Value
Complementary Pairing	Designed as direct PNP counterpart to BC547/BC548 NPN transistors - simplifies push-pull and differential pair design.
Low-Noise Amplification	NF = 2–10 dB at 1 kHz enables use in microphone preamps and sensor signal conditioning without added noise floor degradation.
Pb-Free & RoHS Compliance	Fully compliant with EU RoHS Directive 2011/65/EU and halogen-free/BFR-free requirements - supports green manufacturing mandates.
High-Voltage Tolerance	V_CBO = −50 V and V_CEO = −45 V allow safe operation in industrial control modules with transient-prone −48 V telecom rails.

Applications

Audio Preamp Stage	Discrete Logic Level Shifter
Use Scenario: Amplifying weak signals from electret microphones or piezoelectric sensors in battery-powered voice recorders. IC Role / Device Role / Timing Role: PNP common-emitter amplifier providing 20–40 dB voltage gain with minimal added noise. Use Value: NF = 2–10 dB and h_FE ≥ 200 ensure clean signal amplification without requiring complex feedback compensation.	Use Scenario: Converting 3.3 V CMOS logic outputs to interface with −5 V TTL or ECL inputs in legacy test equipment. IC Role / Device Role / Timing Role: Inverting level shifter using emitter-follower or common-base configuration. Use Value: V_CEO = −45 V and fast f_T = 150 MHz support reliable translation across wide voltage domains with sub-10 ns propagation delay.
LED Driver Switch	Current Mirror Reference
Use Scenario: Sourcing current to drive indicator LEDs or low-power optocouplers in PLC I/O modules. IC Role / Device Role / Timing Role: Saturated PNP switch controlling LED anode connection to positive rail. Use Value: V_CE(sat) ≤ −300 mV reduces power loss and thermal rise during continuous LED operation.	Use Scenario: Building matched current sources in analog front-ends for precision ADC biasing or sensor excitation. IC Role / Device Role / Timing Role: One leg of a discrete two-transistor current mirror with matched h_FE and thermal tracking. Use Value: Tight h_FE binning (Class B: 200–450) and low ICBO (≤ −15 nA) improve mirror accuracy and long-term stability.

Audio Preamp Stage

Discrete Logic Level Shifter

Use Scenario: Amplifying weak signals from electret microphones or piezoelectric sensors in battery-powered voice recorders.

IC Role / Device Role / Timing Role: PNP common-emitter amplifier providing 20–40 dB voltage gain with minimal added noise.

Use Value: NF = 2–10 dB and h_FE ≥ 200 ensure clean signal amplification without requiring complex feedback compensation.

Use Scenario: Converting 3.3 V CMOS logic outputs to interface with −5 V TTL or ECL inputs in legacy test equipment.

IC Role / Device Role / Timing Role: Inverting level shifter using emitter-follower or common-base configuration.

Use Value: V_CEO = −45 V and fast f_T = 150 MHz support reliable translation across wide voltage domains with sub-10 ns propagation delay.

LED Driver Switch

Current Mirror Reference

Use Scenario: Sourcing current to drive indicator LEDs or low-power optocouplers in PLC I/O modules.

IC Role / Device Role / Timing Role: Saturated PNP switch controlling LED anode connection to positive rail.

Use Value: V_CE(sat) ≤ −300 mV reduces power loss and thermal rise during continuous LED operation.

Use Scenario: Building matched current sources in analog front-ends for precision ADC biasing or sensor excitation.

IC Role / Device Role / Timing Role: One leg of a discrete two-transistor current mirror with matched h_FE and thermal tracking.

Use Value: Tight h_FE binning (Class B: 200–450) and low ICBO (≤ −15 nA) improve mirror accuracy and long-term stability.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
BC557BTA	Same die, identical electrical specs; differs only in packaging - Fan-Fold vs Tape & Reel.	No functional difference; selected based on assembly method (manual vs pick-and-place).	Choose BC557BTA for manual prototyping or low-volume hand-soldered builds.
BC558BTA	V_CEO = −30 V (vs −45 V); otherwise identical h_FE, V_CE(sat), and f_T.	Not suitable for −45 V rail systems; limited to ≤ −30 V applications like 5 V/−12 V dual-rail op-amp supplies.	Select BC558BTA only where lower voltage rating is acceptable and cost optimization is prioritized.

Compared with BC557BTA and BC558BTA, the BC557BTAR offers identical performance to BC557BTA but in tape-and-reel format for automated assembly, while providing 15 V higher V_CEO than BC558BTA - making it the preferred choice for −45 V industrial signal conditioning and robust discrete logic interfacing.

Availability

BC557BTAR is available at Aetrix Electronics and suitable for audio preamplifiers, discrete logic level shifters, and LED driver switches requiring stable component supply, consistent parametric binning, and RoHS-compliant through-hole packaging.

Supply support for BC557BTAR 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 delivering energy-efficient, intelligent power and sensing solutions for automotive, industrial, cloud, medical, and IoT applications.

The BC557BTAR belongs to the BC556–BC560 family of general-purpose PNP transistors, engineered for reliability and consistency in cost-sensitive, high-volume analog and mixed-signal designs.

FAQ

What is the maximum collector-emitter voltage rating for BC557BTAR?

The BC557BTAR has a maximum collector-emitter voltage (V_CEO) rating of −45 V at T_A = 25°C. This rating allows safe operation in negative-supply circuits up to −45 V, including industrial control systems and telecom line interfaces. Exceeding this voltage risks avalanche breakdown and permanent device damage. Derating applies above 25°C per the datasheet's thermal characteristics.

Is BC557BTAR pin-compatible with BC547 or BC548 NPN transistors?

No - BC557BTAR is not pin-compatible with BC547 or BC548. While it is electrically complementary (same TO-92-3 footprint and pin numbering: Collector-Base-Emitter), the BC557BTAR is a PNP device with reversed polarity. Physical pinout matches (pin 1 = collector, pin 2 = base, pin 3 = emitter), but circuit implementation requires inverted biasing and supply orientation. Always verify layout polarity in schematic capture.

What does the "B" in BC557BTAR signify?

The "B" in BC557BTAR denotes the h_FE (DC current gain) classification grade: 200–450 at V_CE = −5 V and I_C = −2 mA. This distinguishes it from BC557ATA (h_FE = 110–220, Class A) and BC557CTA (h_FE = 420–800, Class C). The "TAR" suffix indicates tape-and-reel packaging in Case 135AR (lead-formed TO-92).

Can BC557BTAR be used in low-noise audio applications?

Yes - BC557BTAR is specified for low-noise operation with a noise figure (NF) of 2–10 dB at 1 kHz, I_C = −200 µA, and R_G = 2 kΩ. This makes it suitable for first-stage preamplification of microphones and piezoelectric sensors where minimizing added noise is critical. Performance is validated per onsemi's BC556–BC560 family characterization.

What is the thermal resistance (R_JA) of BC557BTAR on a standard PCB?

The BC557BTAR has a junction-to-ambient thermal resistance (R_JA) of 250 °C/W when mounted on a standard FR-4 PCB measuring 76 mm × 114 mm × 1.57 mm with minimum land pattern. This value assumes natural convection cooling; forced airflow or copper pour enhancements can reduce effective R_JA. Derating begins at 4.0 mW/°C above 25°C ambient.

BC557BTAR Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

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):: 100 mA

Voltage - Collector Emitter Breakdown (Max):: 45 V

Vce Saturation (Max) @ Ib, Ic:: 650mV @ 5mA, 100mA

Current - Collector Cutoff (Max):: 15nA (ICBO)

DC Current Gain (hFE) (Min) @ Ic, Vce:: 200 @ 2mA, 5V

Power - Max:: 500 mW

Frequency - Transition:: 150MHz

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-92-3

BC557BTAR FAQ

1.How can I place an order for BC557BTAR through Aetrix?

Please submit a Request for Quotation (RFQ) for BC557BTAR 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 BC557BTAR reliable?

The price and inventory of BC557BTAR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BC557BTAR is usually 5 days.

3.What payment methods are accepted for BC557BTAR?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BC557BTAR transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for BC557BTAR?

BC557BTAR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your BC557BTAR 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 BC557BTAR?

For technical support, including BC557BTAR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BC557BTAR requirements.

6.How does Aetrix verify that BC557BTAR is sourced from the original manufacturer or authorized distributors?

All BC557BTAR 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 BC557BTAR meets industry standards.

7.What is the process for return or replacement of BC557BTAR?

All BC557BTAR units undergo pre-shipment inspection (PSI). If there is an issue with BC557BTAR, 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 BC557BTAR part is unused and in its original packaging.

Return procedure for BC557BTAR:

1.Submit a request within 90 days.

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

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