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

NXP Semiconductors BC556A,112

Name: BC556A,112
Brand: NXP Semiconductors
SKU: BC556A,112
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: BC556A,112

Manufacturer:: NXP Semiconductors

Category:: Single Bipolar Transistors

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

Datasheet:: BC556A,112.pdf

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

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Product details

Overview

BC556A,112 from NXP Semiconductors is a PNP general-purpose bipolar junction transistor in TO-92 (SOT54) package, rated for −65 V V_CEO, −80 V V_CBO, −100 mA I_C, 500 mW P_tot, and DC current gain h_FE of 125–250 at I_C = −2 mA. It serves as a low-voltage, low-current switch or linear amplifier in discrete analog and digital interface circuits.

For engineers reviewing the BC556A,112 datasheet, BC556A,112 pinout, BC556A,112 application, or BC556A,112 equivalent, key selection criteria include verified V_CEO/V_CBO ratings, h_FE binning (A-grade), TO-92 thermal resistance (250 K/W), saturation voltage under defined I_C/I_B, and compatibility with BC546/BC547 NPN complements.

Technical Context

The BC556A,112 operates as a silicon PNP BJT with fixed emitter-base and collector-base junctions, optimized for linear amplification and saturated switching in ambient temperatures from −65 °C to +150 °C. Its h_FE range (125–250) is specified at V_CE = −5 V and I_C = −2 mA, with V_BE = −600 to −750 mV under same conditions.

Thermal performance is defined for FR4 PCB mounting: R_th(j-a) = 250 K/W. Saturation behavior is characterized at two operating points - V_CEsat ≤ −300 mV at I_C = −10 mA/I_B = −0.5 mA, and ≤ −650 mV at I_C = −100 mA/I_B = −5 mA - confirming suitability for moderate-speed switching.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	−65 V: Maximum allowable collector-emitter voltage with base open; defines safe blocking capability in PNP switch configurations.
h_FE	125–250 at I_C = −2 mA, V_CE = −5 V: Confirmed DC current gain range for A-grade bin; enables predictable base drive calculation.
V_CEsat	≤ −300 mV at I_C = −10 mA/I_B = −0.5 mA: Low saturation voltage ensures minimal power loss and heat generation in on-state switching.
P_tot	500 mW at T_amb ≤ 25 °C: Absolute maximum dissipation limit; requires derating above 25 °C per R_th(j-a) = 250 K/W.
f_T	100 MHz: Transition frequency at V_CE = −5 V, I_C = −10 mA; indicates usable bandwidth for small-signal amplification up to ~10 MHz.
C_c	3 pF at V_CB = −10 V: Collector-base capacitance impacts high-frequency response and stability in amplifier designs.

Pinout & Package

BC556A,112 is housed in a plastic single-ended leaded (through-hole) TO-92 package, also designated SC-43A or SOT54, with 3 leads and standard 2.54 mm lead pitch.

Pin/Terminal	Circuit Role	Design Meaning
1	Emitter	Current exit terminal in PNP operation; connected to higher potential rail in common-emitter switch layouts.
2	Base	Control terminal; negative bias relative to emitter required to forward-bias base-emitter junction and enable conduction.
3	Collector	Current entry terminal; tied to load and supply return in typical switching applications.

Key Features

Feature	Design Value
Low-voltage PNP switching	Rated for −65 V V_CEO and −80 V V_CBO, enabling use in 24 V and lower DC systems with margin.
A-grade h_FE binning	Guaranteed 125–250 h_FE at I_C = −2 mA, simplifying base resistor selection for consistent turn-on across production lots.
TO-92 thermal performance	R_th(j-a) = 250 K/W on FR4 board supports reliable operation up to 500 mW at room ambient without heatsinking.
Complementary NPN pairing	Designed as direct counterpart to BC546/BC547, enabling matched push-pull and differential pair implementations.

Applications

Audio Pre-amplifier Stage	Level-Shifting Interface
Use Scenario: Amplifying weak microphone or sensor signals in battery-powered portable audio devices. IC Role / Device Role / Timing Role: Linear PNP amplifier in common-emitter configuration with emitter degeneration for stable gain. Use Value: h_FE = 125–250 and f_T = 100 MHz support clean mid-band amplification (20 Hz–20 kHz) with low distortion.	Use Scenario: Translating logic-level signals between 5 V microcontroller outputs and −12 V analog circuitry. IC Role / Device Role / Timing Role: Inverting level shifter using PNP topology to invert and shift voltage domain. Use Value: Verified V_CEO = −65 V and V_BE = −600 to −750 mV ensure reliable turn-on and rail-to-rail swing capability.
Relay Driver Circuit	Discrete Logic Inverter
Use Scenario: Driving 12 V relay coils from 3.3 V or 5 V GPIO pins in industrial control modules. IC Role / Device Role / Timing Role: Saturated PNP switch with base resistor limiting I_B to achieve forced β ≥ 20. Use Value: V_CEsat ≤ −300 mV at I_C = −10 mA minimizes coil power loss and self-heating during continuous duty.	Use Scenario: Implementing active-low logic inversion in legacy TTL-compatible subsystems where IC-level gates are unavailable. IC Role / Device Role / Timing Role: Single-transistor inverter with pull-up resistor, leveraging PNP's natural inversion characteristic. Use Value: Guaranteed h_FE range and low V_CEsat ensure sharp transition and noise margin compliance per TTL input thresholds.

Audio Pre-amplifier Stage

Level-Shifting Interface

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

IC Role / Device Role / Timing Role: Linear PNP amplifier in common-emitter configuration with emitter degeneration for stable gain.

Use Value: h_FE = 125–250 and f_T = 100 MHz support clean mid-band amplification (20 Hz–20 kHz) with low distortion.

Use Scenario: Translating logic-level signals between 5 V microcontroller outputs and −12 V analog circuitry.

IC Role / Device Role / Timing Role: Inverting level shifter using PNP topology to invert and shift voltage domain.

Use Value: Verified V_CEO = −65 V and V_BE = −600 to −750 mV ensure reliable turn-on and rail-to-rail swing capability.

Relay Driver Circuit

Discrete Logic Inverter

Use Scenario: Driving 12 V relay coils from 3.3 V or 5 V GPIO pins in industrial control modules.

IC Role / Device Role / Timing Role: Saturated PNP switch with base resistor limiting I_B to achieve forced β ≥ 20.

Use Value: V_CEsat ≤ −300 mV at I_C = −10 mA minimizes coil power loss and self-heating during continuous duty.

Use Scenario: Implementing active-low logic inversion in legacy TTL-compatible subsystems where IC-level gates are unavailable.

IC Role / Device Role / Timing Role: Single-transistor inverter with pull-up resistor, leveraging PNP's natural inversion characteristic.

Use Value: Guaranteed h_FE range and low V_CEsat ensure sharp transition and noise margin compliance per TTL input thresholds.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
BC557,112	Lower V_CEO (−45 V) and V_CBO (−50 V); wider h_FE range (125–800).	Less suitable for 48 V or higher blocking; better for high-gain amplification where wide h_FE spread is acceptable.	Select BC557,112 only if system voltage < 40 V and gain variability is tolerable.
MMBT5551LT1G	SMT SOT-23 package; NPN polarity; V_CEO = 160 V; h_FE = 80–250; not pin-compatible.	Requires PCB redesign; used where high-voltage NPN switching is needed instead of PNP.	Choose MMBT5551LT1G only for surface-mount NPN replacement with higher voltage rating - not a drop-in substitute.

Compared with BC557,112 and MMBT5551LT1G, BC556A,112 provides the optimal balance of −65 V blocking, A-grade h_FE consistency, through-hole TO-92 serviceability, and proven interoperability with BC546/BC547 in dual-rail analog and interface designs.

Availability

BC556A,112 is available at Aetrix Electronics and suitable for audio pre-amplifiers, relay drivers, level-shifting interfaces, and discrete logic inverters requiring stable component supply and long-term obsolescence management.

Supply support for BC556A,112 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

NXP Semiconductors is a global semiconductor company headquartered in Eindhoven, Netherlands, specializing in secure connectivity solutions for automotive, industrial, and consumer applications.

The BC556A,112 belongs to NXP's legacy general-purpose transistor product line, designed specifically for cost-sensitive, reliability-critical through-hole analog and switching functions in industrial controls, instrumentation, and legacy-compatibility systems.

FAQ

What is the maximum collector-emitter voltage rating for BC556A,112?

The BC556A,112 has a maximum collector-emitter voltage (V_CEO) rating of −65 V with the base open, as specified in the Absolute Maximum Ratings table. This value defines the upper limit for safe DC blocking in common-emitter configurations and must not be exceeded to prevent junction breakdown. Derating is required at elevated ambient temperatures per the device's thermal resistance profile.

Is BC556A,112 pin-compatible with BC557 variants?

Yes, BC556A,112 shares identical TO-92 (SOT54) pinout - emitter (pin 1), base (pin 2), collector (pin 3) - with BC557 series transistors. However, BC556A,112 and BC557,112 differ in V_CEO (−65 V vs. −45 V) and h_FE range (125–250 vs. 125–800), so substitution requires verification of voltage and gain requirements in the target circuit.

What is the typical DC current gain (h_FE) of BC556A,112 at I_C = −2 mA?

The BC556A,112 exhibits a guaranteed h_FE range of 125 to 250 when tested at I_C = −2 mA and V_CE = −5 V, per its A-grade binning specification. This range is narrower than BC556B or BC557C variants, providing tighter gain predictability for precision biasing and consistent switching thresholds in production hardware.

Can BC556A,112 be used in surface-mount designs?

No - BC556A,112 is exclusively offered in the through-hole TO-92 (SOT54) package and lacks an SMT variant. For surface-mount equivalents, engineers should evaluate functionally similar PNP transistors such as the PZT5551 or MMBT5551 in SOT-23, but note polarity (NPN), voltage rating, and pinout differences require full circuit validation before substitution.

What is the thermal resistance from junction to ambient for BC556A,112?

The BC556A,112 has a thermal resistance from junction to ambient (R_th(j-a)) of 250 K/W when mounted on a standard FR4 printed-circuit board, as stated in the Thermal Characteristics section. This value assumes no heatsink and defines the temperature rise per watt dissipated - e.g., at 300 mW, junction temperature rises ~75 °C above ambient.

BC556A,112 Specifications

Product attributes: Attribute value

Manufacturer:: NXP Semiconductors

Series:: -

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

Packaging:: Bulk

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:: 125 @ 2mA, 5V

Power - Max:: 500 mW

Frequency - Transition:: 100MHz

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-92-3

BC556A,112 FAQ

1.How can I place an order for BC556A,112 through Aetrix?

Please submit a Request for Quotation (RFQ) for BC556A,112 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 BC556A,112 reliable?

The price and inventory of BC556A,112 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BC556A,112 is usually 5 days.

3.What payment methods are accepted for BC556A,112?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BC556A,112 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for BC556A,112?

BC556A,112 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your BC556A,112 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 BC556A,112?

For technical support, including BC556A,112 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BC556A,112 requirements.

6.How does Aetrix verify that BC556A,112 is sourced from the original manufacturer or authorized distributors?

All BC556A,112 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 BC556A,112 meets industry standards.

7.What is the process for return or replacement of BC556A,112?

All BC556A,112 units undergo pre-shipment inspection (PSI). If there is an issue with BC556A,112, 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 BC556A,112 part is unused and in its original packaging.

Return procedure for BC556A,112:

1.Submit a request within 90 days.

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

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