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

onsemi BC556ATA

Name: BC556ATA
Brand: onsemi
SKU: BC556ATA
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: BC556ATA

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

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

Datasheet:: BC556ATA.pdf

Description:: TRANS PNP 65V 0.1A TO-92-3

Quantity:: RFQ Add To RFQ list

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Inventory:281,490

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Product details

Overview

BC556ATA 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 = −65 V, I_C = −100 mA, h_FE = 110–220 (Class A), V_CE(sat) ≤ −300 mV at I_C = −10 mA/I_B = −0.5 mA, and operates up to 150 MHz f_T. It is commonly used in discrete amplifier stages, level-shifting interfaces, and relay drivers.

For engineers reviewing the BC556ATA datasheet, pinout, applications, or equivalent options, key selection criteria include its −65 V collector-emitter breakdown rating, TO-92-3 (case 135AR) leadformed package, Class A h_FE range, low-noise capability relative to BC557/BC558 variants, and complementarity with BC546–BC550 NPN series.

Technical Context

The BC556ATA is a discrete bipolar junction transistor (BJT) with fixed PNP polarity and current-controlled gain architecture. Its DC current gain (h_FE) is binned to Class A (110–220), ensuring predictable biasing in amplifier configurations where moderate gain stability is required.

It supports both switching and linear operation modes, with verified saturation performance (V_CE(sat) ≤ −300 mV) under standard test conditions and thermal resistance R_JA = 250 °C/W on FR-4 PCBs. The device is Pb-free, halogen-free/BFR-free, and RoHS compliant per onsemi's 2024 datasheet revision.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	−65 V - Maximum safe collector-to-emitter voltage before breakdown in common-emitter configuration.
I_C (DC)	−100 mA - Continuous collector current limit; defines maximum load drive capability in switching or amplification.
h_FE Class	A (110–220) - Guaranteed DC current gain range at V_CE = −5 V, I_C = −2 mA; enables stable bias design.
V_CE(sat)	≤ −300 mV @ I_C = −10 mA / I_B = −0.5 mA - Low saturation voltage ensures minimal power loss in switch-on state.
f_T	150 MHz - Current gain bandwidth product; supports RF amplification up to mid-VHF band.
P_D	500 mW @ T_A = 25°C - Maximum power dissipation; derates 4.0 mW/°C above ambient.
C_ob	6 pF @ V_CB = −10 V - Output capacitance affects high-frequency response and stability in tuned circuits.

Pinout & Package

BC556ATA is housed in a TO-92-3 package (case 135AR), leadformed configuration, with standardized pinout: Pin 1 = Collector, Pin 2 = Base, Pin 3 = Emitter.

Pin/Terminal	Circuit Role	Design Meaning
1 (Collector)	Current sink terminal	Connected to higher potential (e.g., V_CC rail in PNP switch); carries full load current.
2 (Base)	Control input	Receives forward-biased current to turn on transistor; requires current-limiting resistor in most designs.
3 (Emitter)	Current source terminal	Typically tied to supply rail in common-emitter switch; provides reference for base bias network.

Key Features

Feature	Design Value
High-voltage PNP switching	Supports −65 V V_CEO, enabling use in 48 V industrial control and legacy telecom interface circuits.
Class A h_FE binning	Guaranteed 110–220 gain range simplifies bias network calculation and improves production yield consistency.
Low V_CE(sat)	≤ −300 mV ensures <1% voltage drop across transistor in saturated switch mode at 10 mA load.
RoHS-compliant packaging	TO-92-3 case 135AR meets global environmental regulations without requiring process requalification.
Complementary NPN pairing	Designed as direct counterpart to BC546–BC550 series, facilitating push-pull and differential pair implementation.

Applications

Audio Pre-amplifier Stage	Industrial Level Shifter
Use Scenario: Amplifying weak microphone or sensor signals in battery-powered portable audio devices. IC Role / Device Role / Timing Role: Discrete PNP BJT configured in common-emitter topology for voltage gain and impedance matching. Use Value: Class A h_FE ensures consistent small-signal gain; −65 V rating allows operation from ±24 V rails without risk of breakdown.	Use Scenario: Translating logic-level signals between 3.3 V microcontrollers and 12 V/24 V industrial actuators or sensors. IC Role / Device Role / Timing Role: PNP switch in emitter-follower or common-emitter inverter configuration for bidirectional level translation. Use Value: Low V_CE(sat) minimizes voltage offset; TO-92 package enables compact placement near I/O headers.
Relay Driver Circuit	Discrete Oscillator Core
Use Scenario: Driving 5–12 V electromagnetic relays in HVAC controllers and PLC I/O modules. IC Role / Device Role / Timing Role: Saturated PNP switch controlling relay coil current path to ground. Use Value: −100 mA I_C rating covers typical 40–80 mA relay coils; robust V_CEO prevents flyback-induced failure.	Use Scenario: Building fundamental-frequency oscillator stages in low-cost signal generators or function generator front-ends. IC Role / Device Role / Timing Role: Active device in phase-shift or Hartley oscillator topology providing gain and feedback control. Use Value: 150 MHz f_T supports stable oscillation up to ~10 MHz; low C_ob reduces frequency drift with temperature.

Audio Pre-amplifier Stage

Industrial Level Shifter

Use Scenario: Amplifying weak microphone or sensor signals in battery-powered portable audio devices.

IC Role / Device Role / Timing Role: Discrete PNP BJT configured in common-emitter topology for voltage gain and impedance matching.

Use Value: Class A h_FE ensures consistent small-signal gain; −65 V rating allows operation from ±24 V rails without risk of breakdown.

Use Scenario: Translating logic-level signals between 3.3 V microcontrollers and 12 V/24 V industrial actuators or sensors.

IC Role / Device Role / Timing Role: PNP switch in emitter-follower or common-emitter inverter configuration for bidirectional level translation.

Use Value: Low V_CE(sat) minimizes voltage offset; TO-92 package enables compact placement near I/O headers.

Relay Driver Circuit

Discrete Oscillator Core

Use Scenario: Driving 5–12 V electromagnetic relays in HVAC controllers and PLC I/O modules.

IC Role / Device Role / Timing Role: Saturated PNP switch controlling relay coil current path to ground.

Use Value: −100 mA I_C rating covers typical 40–80 mA relay coils; robust V_CEO prevents flyback-induced failure.

Use Scenario: Building fundamental-frequency oscillator stages in low-cost signal generators or function generator front-ends.

IC Role / Device Role / Timing Role: Active device in phase-shift or Hartley oscillator topology providing gain and feedback control.

Use Value: 150 MHz f_T supports stable oscillation up to ~10 MHz; low C_ob reduces frequency drift with temperature.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
BC556BTA	Higher h_FE bin (200–450); otherwise identical electrical specs and package.	Suitable where higher gain reduces base drive requirements; may require bias recalibration.	Select BC556BTA when tighter gain tolerance or lower base current is needed; BC556ATA preferred for cost-sensitive, moderate-gain designs.
BC557ATA	V_CEO = −45 V (vs. −65 V); same h_FE Class A, TO-92-3 package, and pinout.	Limited to ≤36 V systems; not interchangeable in high-voltage industrial interfaces.	Choose BC557ATA only if system voltage stays below 40 V; BC556ATA remains mandatory for 48 V or legacy telecom applications.

Compared with BC556BTA and BC557ATA, the BC556ATA offers the optimal balance of voltage rating, gain consistency, and cost for general-purpose PNP switching-retaining −65 V robustness while avoiding over-specification in gain or under-specification in breakdown margin.

Availability

BC556ATA is available at Aetrix Electronics and suitable for industrial control systems, audio signal conditioning circuits, and relay driver modules requiring stable component supply and long-term manufacturability.

Supply support for BC556ATA 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 manufacturer specializing in energy-efficient power management, analog, and discrete components for automotive, industrial, and consumer markets.

The BC556ATA belongs to onsemi's legacy BC5xx PNP/NPN transistor family, engineered for reliability in general-purpose analog and switching applications where proven performance, wide operating margins, and long-lifecycle support are critical.

FAQ

What is the maximum collector-emitter voltage rating for BC556ATA?

The BC556ATA has a guaranteed V_CEO rating of −65 V at T_A = 25°C, making it suitable for circuits operating up to ±48 V rails. This rating is confirmed in onsemi's June 2024 datasheet Rev. 3, Absolute Maximum Ratings table. Exceeding this voltage risks irreversible junction breakdown. Derating applies at elevated temperatures per thermal characteristics data.

Is BC556ATA pin-compatible with BC556BTA?

Yes, BC556ATA and BC556BTA share identical TO-92-3 (case 135AR) packaging, pinout (Collector-Base-Emitter), and all absolute maximum ratings. The only difference is h_FE binning: BC556ATA is Class A (110–220), while BC556BTA is Class B (200–450). No PCB changes are required for substitution, but bias networks may need verification.

Does BC556ATA support low-noise audio applications?

No-BC556ATA is not specified for low-noise operation. The onsemi datasheet assigns low-noise performance only to BC559 and BC560 variants (NF = 1–4 dB). BC556ATA's noise figure is rated at 2–10 dB under standard conditions, making it appropriate for general amplification but not high-fidelity preamp stages where BC559CTA would be preferred.

What is the thermal resistance of BC556ATA in standard PCB layout?

The BC556ATA has a junction-to-ambient thermal resistance (R_JA) of 250 °C/W when mounted on a 76 mm × 114 mm FR-4 PCB with minimum land pattern. This value assumes natural convection cooling and is used to calculate maximum allowable power dissipation at elevated ambient temperatures using the 4.0 mW/°C derating factor.

Can BC556ATA replace BC557ATA in existing designs?

Only with voltage derating. BC556ATA has V_CEO = −65 V versus BC557ATA's −45 V. Substituting BC556ATA into a BC557ATA design is safe and improves margin. Replacing BC556ATA with BC557ATA risks failure if circuit voltages exceed 45 V. Always verify worst-case V_CE in the target application before interchange.

BC556ATA Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

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

Packaging:: Cut Tape (CT)

Product Status:: Obsolete

Transistor Type:: PNP

Current - Collector (Ic) (Max):: 100 mA

Voltage - Collector Emitter Breakdown (Max):: 65 V

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

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

DC Current Gain (hFE) (Min) @ Ic, Vce:: 110 @ 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

BC556ATA FAQ

1.How can I place an order for BC556ATA through Aetrix?

Please submit a Request for Quotation (RFQ) for BC556ATA 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 BC556ATA reliable?

The price and inventory of BC556ATA are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BC556ATA is usually 5 days.

3.What payment methods are accepted for BC556ATA?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BC556ATA transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for BC556ATA?

BC556ATA orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your BC556ATA 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 BC556ATA?

For technical support, including BC556ATA datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BC556ATA requirements.

6.How does Aetrix verify that BC556ATA is sourced from the original manufacturer or authorized distributors?

All BC556ATA 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 BC556ATA meets industry standards.

7.What is the process for return or replacement of BC556ATA?

All BC556ATA units undergo pre-shipment inspection (PSI). If there is an issue with BC556ATA, 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 BC556ATA part is unused and in its original packaging.

Return procedure for BC556ATA:

1.Submit a request within 90 days.

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

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