BC556CBU Equivalent & Substitute Parts

Part Overview

The BC556CBU is a small-signal PNP bipolar junction transistor manufactured by onsemi, housed in a TO-92-3 through-hole package. This device is rated for 65 V collector-emitter breakdown voltage, 100 mA maximum collector current, and 500 mW power dissipation. The BC556CBU is classified as obsolete, making identification of functionally equivalent substitute parts necessary for ongoing design support and procurement continuity. Equivalent parts must maintain electrical and mechanical compatibility across critical parameters including voltage ratings, current handling, frequency response, and package configuration.

Substiute Parts

BC556CBU

onsemiIn Stock: 1131BC556CBU Datasheet

Current PartRFQ

BC556BTA

Fairchild SemiconductorIn Stock: 18331BC556BTA Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the BC556CBU is determined by strict equivalence across the following critical parameters:

Electrical Equivalence Criteria:

• Transistor polarity: PNP configuration
• Voltage rating: 65 V collector-emitter breakdown voltage (maximum)
• Current rating: 100 mA maximum collector current
• Saturation voltage: 650 mV @ 5 mA, 100 mA
• Collector cutoff current: 15 nA (ICBO)
• Power dissipation: 500 mW maximum
• Frequency response: 150 MHz transition frequency

Mechanical Equivalence Criteria:

• Package type: TO-92-3 through-hole configuration
• Lead configuration: Standard TO-226AA formed leads
• Mounting method: Through-hole PCB insertion

The BC556BTA qualifies as a direct substitute based on matching all electrical parameters and package specifications. Differences in DC current gain (hFE) minimum specification (200 @ 2 mA, 5 V for BC556BTA versus 420 @ 2 mA, 5 V for BC556CBU) do not preclude substitution, as the BC556BTA specification remains within acceptable operating ranges for general-purpose small-signal switching and amplification applications. The BC556BTA maintains active product status, ensuring ongoing availability and supply chain continuity.

Parameter Comparison

Engineering Selection Recommendations

BC556BTA Selection Basis:

The BC556BTA is the primary substitute for the BC556CBU based on the following engineering factors:

1. Product Status Alignment: The BC556BTA maintains active product status with confirmed inventory availability (18,244 pcs), whereas the BC556CBU is classified as obsolete. This status differential ensures long-term supply chain viability and reduces procurement risk.

2. Electrical Parameter Equivalence: All critical electrical specifications match or exceed the BC556CBU requirements. The DC current gain specification of the BC556BTA (200 @ 2 mA, 5 V) is lower than the BC556CBU (420 @ 2 mA, 5 V) but remains within acceptable operating parameters for small-signal switching and amplification circuits.

3. Mechanical Compatibility: Both devices utilize identical TO-92-3 through-hole packaging with formed leads, ensuring direct PCB footprint compatibility without layout modification.

4. Regulatory Compliance: Both parts carry identical ECCN (EAR99) and HTSUS (8541.21.0075) classifications, maintaining compliance consistency across supply chain transitions.

5. Manufacturer Transition: Substitution from onsemi (BC556CBU) to Fairchild Semiconductor (BC556BTA) represents a standard industry practice for obsolete component replacement, with both manufacturers maintaining equivalent quality and reliability standards for this device category.

Frequently Asked Questions (FAQ)

Q: Can the BC556BTA directly replace the BC556CBU in existing designs without circuit modification?

A: Yes. The BC556BTA provides direct electrical and mechanical substitution. All voltage ratings, current ratings, saturation characteristics, and package configurations are equivalent. The lower DC current gain specification of the BC556BTA does not require circuit redesign for general-purpose small-signal applications.

Q: What is the significance of the DC current gain (hFE) difference between these parts?

A: The BC556CBU specifies a minimum hFE of 420 @ 2 mA, 5 V, while the BC556BTA specifies 200 @ 2 mA, 5 V. This difference reflects manufacturing tolerance variations between manufacturers. For circuits designed with the BC556CBU's hFE specification, the BC556BTA's lower gain may result in slightly reduced amplification in linear amplifier configurations. However, for switching applications and circuits with gain margin, this difference is not operationally significant.

Q: Are the TO-92-3 packages physically identical between these parts?

A: Yes. Both the BC556CBU and BC556BTA use the TO-92-3 (TO-226AA) through-hole package with formed leads. Pin assignments, lead spacing, and PCB hole patterns are identical, enabling direct socket substitution.

Q: Why is the BC556CBU classified as obsolete?

A: The BC556CBU is listed as obsolete by onsemi, indicating discontinued manufacturing and end-of-life status. The BC556BTA, manufactured by Fairchild Semiconductor, remains in active production and represents the recommended substitute for ongoing procurement and new design applications.

Q: Are there any compliance or certification differences between these parts?

A: No. Both parts carry identical ECCN (EAR99) and HTSUS (8541.21.0075) classifications. Moisture sensitivity level (MSL) for the BC556CBU is rated as 1 (Unlimited). Regulatory compliance remains consistent across the substitution.

Q: What applications are suitable for the BC556BTA as a BC556CBU replacement?

A: The BC556BTA is suitable for all applications previously served by the BC556CBU, including small-signal switching, amplification, and general-purpose logic circuits operating within the specified voltage (65 V maximum), current (100 mA maximum), and frequency (150 MHz) parameters.