BC558A-AP Equivalent & Substitute Parts

Part Overview

The BC558A-AP is a PNP bipolar junction transistor manufactured by Micro Commercial Co, designed for general-purpose switching and amplification applications. This device features a maximum collector current of 100 mA, collector-emitter breakdown voltage of 30 V, and maximum power dissipation of 625 mW in a Through Hole TO-92 package. The BC558A-AP is classified as obsolete, making identification of suitable substitute components necessary for ongoing design support and procurement continuity.

Substiute Parts

BC558A-AP

Micro Commercial CoIn Stock: 1156BC558A-AP Datasheet

Current PartRFQ

2N3906TA

Fairchild SemiconductorIn Stock: 323632N3906TA Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution of the BC558A-AP is determined by compatibility across the following critical parameters:

Transistor Type: Both the main part and substitute must be PNP bipolar junction transistors to maintain circuit polarity and biasing requirements.

Package / Case: The TO-92-3 package is mandatory for mechanical and thermal compatibility with existing PCB layouts and through-hole assembly processes.

Mounting Type: Through Hole mounting must be preserved to ensure compatibility with legacy designs and assembly equipment.

Electrical Ratings: Substitute parts must meet or exceed the maximum ratings of the BC558A-AP in collector current (100 mA), collector-emitter breakdown voltage (30 V), and power dissipation (625 mW). Transition frequency and operating temperature range must support the intended application envelope.

Product Status: Active product status is preferred to ensure long-term availability and supply chain stability.

The 2N3906TA meets all substitution criteria with enhanced electrical performance characteristics while maintaining identical package and mounting specifications.

Parameter Comparison

Engineering Selection Recommendations

The BC558A-AP is classified as obsolete, necessitating transition to an active equivalent for new designs and ongoing production support. The 2N3906TA from Fairchild Semiconductor is a direct substitute that maintains identical package, mounting type, and operating temperature specifications while providing enhanced electrical performance.

The 2N3906TA offers superior ratings in maximum collector current (200 mA versus 100 mA) and collector-emitter breakdown voltage (40 V versus 30 V), providing design margin for applications operating near the BC558A-AP limits. The transition frequency is increased to 250 MHz, supporting higher-speed switching applications. Both devices share identical maximum power dissipation (625 mW) and operating temperature range (-55°C to 150°C).

The 2N3906TA maintains active product status with established supply chain availability, eliminating obsolescence risk. Both devices are RoHS3 compliant and carry identical ECCN and HTSUS classifications, ensuring regulatory and trade compliance continuity.

Frequently Asked Questions (FAQ)

Q: Can the 2N3906TA directly replace the BC558A-AP in existing designs?

A: Yes. Both devices are PNP bipolar junction transistors in identical TO-92-3 packages with Through Hole mounting. The 2N3906TA meets or exceeds all maximum electrical ratings of the BC558A-AP, including collector current, breakdown voltage, power dissipation, and operating temperature range. No PCB layout modifications are required.

Q: What are the key differences between these two transistors?

A: The 2N3906TA provides enhanced performance specifications: maximum collector current of 200 mA (versus 100 mA), collector-emitter breakdown voltage of 40 V (versus 30 V), and transition frequency of 250 MHz (versus 150 MHz). The 2N3906TA exhibits lower saturation voltage (400 mV versus 650 mV at comparable test conditions). The BC558A-AP is obsolete; the 2N3906TA is active.

Q: Are there any compatibility concerns with package or pinout?

A: No. Both devices use the TO-92-3 package with identical Through Hole lead configuration. Pinout is identical: Base, Collector, and Emitter in standard TO-92 orientation. Direct socket substitution is supported.

Q: Does the higher transition frequency of the 2N3906TA affect circuit operation?

A: The higher transition frequency (250 MHz versus 150 MHz) of the 2N3906TA does not degrade performance in applications designed for the BC558A-AP. This parameter represents maximum switching capability; circuits operating at lower frequencies experience no adverse effects. Applications requiring higher-speed switching benefit from this enhanced specification.

Q: Are regulatory and compliance certifications identical?

A: Both devices carry identical ECCN (EAR99) and HTSUS (8541.21.0075) classifications. Both are RoHS3 compliant. Regulatory and trade compliance requirements are maintained with the 2N3906TA substitution.

Q: What is the DC current gain difference between these transistors?

A: The BC558A-AP specifies minimum DC current gain (hFE) of 120 at 2 mA collector current and 5 V collector-emitter voltage. The 2N3906TA specifies minimum hFE of 100 at 10 mA collector current and 1 V collector-emitter voltage. These measurements are taken at different operating points; direct comparison requires evaluation at identical test conditions for specific circuit applications.