BC548B Equivalent & Substitute Parts

Part Overview

The BC548B is an NPN bipolar junction transistor manufactured by onsemi in a through-hole TO-92 package. This device is rated for 30 V collector-emitter breakdown voltage, 100 mA maximum collector current, and 625 mW power dissipation. The BC548B operates across a temperature range of -55°C to 150°C and features a 300 MHz transition frequency.

The BC548B is classified as obsolete. Equivalent and substitute parts are necessary to support ongoing applications where this component is no longer readily available through standard procurement channels or where design flexibility permits the use of alternative devices meeting the same functional requirements.

Substiute Parts

BC548B

onsemiIn Stock: 5268BC548B Datasheet

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MMBT100

onsemiIn Stock: 65415MMBT100 Datasheet

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LP395Z/LFT1

Texas InstrumentsIn Stock: 6615LP395Z/LFT1 Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution of the BC548B is determined by the following electrical and mechanical parameters:

Primary Substitution Criteria:

• Transistor type must be NPN
• Collector-emitter breakdown voltage must equal or exceed 30 V
• Maximum collector current must equal or exceed 100 mA
• Maximum power dissipation must equal or exceed 625 mW
• Operating temperature range must encompass the application requirements
• Mounting type and package compatibility with the circuit board design

Substitute Parts Identified:

The MMBT100 (onsemi) is a surface-mount NPN transistor with 45 V breakdown voltage, 500 mA collector current, and 350 mW power rating. This device exceeds the electrical specifications of the BC548B but operates in a different package format (SOT-23-3 surface mount versus TO-92 through hole).

The LP395Z/LFT1 (Texas Instruments) is a through-hole NPN transistor with 36 V breakdown voltage and TO-92-3 package compatibility. This device maintains the same mounting type as the BC548B and meets the voltage specification requirement.

Parameter Comparison

Engineering Selection Recommendations

LP395Z/LFT1 (Texas Instruments) is the preferred substitute for direct replacement in through-hole applications. This device maintains identical package geometry (TO-92-3), supports the same mounting methodology, and provides 36 V breakdown voltage exceeding the BC548B requirement of 30 V. The LP395Z/LFT1 is actively manufactured and carries ROHS3 compliance certification. The operating temperature range of 0°C to 125°C is narrower than the BC548B specification; applications requiring operation below 0°C or above 125°C must evaluate thermal performance independently.

MMBT100 (onsemi) is suitable for applications where surface-mount technology is acceptable or preferred. This device provides superior electrical performance with 45 V breakdown voltage and 500 mA collector current capacity. The MMBT100 is actively manufactured and ROHS3 compliant. Circuit board redesign is required to accommodate the SOT-23-3 package format. The 350 mW power rating is lower than the BC548B; applications requiring sustained power dissipation above 350 mW must verify thermal management adequacy.

Both substitute parts are actively produced and carry current RoHS compliance certifications, addressing the non-compliant status of the obsolete BC548B.

Frequently Asked Questions (FAQ)

Q: Can the MMBT100 replace the BC548B in an existing circuit board?

A: Direct replacement on the circuit board is not possible. The MMBT100 uses a surface-mount SOT-23-3 package, while the BC548B uses a through-hole TO-92-3 package. Circuit board redesign and component footprint modification are required. Electrical compatibility is confirmed for applications within the specified parameter ranges.

Q: What is the primary advantage of the LP395Z/LFT1 as a substitute?

A: The LP395Z/LFT1 maintains identical through-hole TO-92-3 package geometry, enabling direct physical replacement without circuit board modification. The 36 V breakdown voltage specification exceeds the BC548B requirement of 30 V. Both devices are NPN transistors with compatible pinout configurations.

Q: Are there temperature range limitations when using the LP395Z/LFT1?

A: The LP395Z/LFT1 operates from 0°C to 125°C, compared to the BC548B range of -55°C to 150°C. Applications requiring operation below 0°C or above 125°C must verify that the LP395Z/LFT1 meets the specific thermal requirements of the design.

Q: Why is the MMBT100 power rating lower than the BC548B despite higher current capacity?

A: The MMBT100 is rated for 350 mW maximum power dissipation, while the BC548B is rated for 625 mW. This difference reflects the thermal characteristics of the surface-mount SOT-23-3 package compared to the through-hole TO-92-3 package. Applications requiring sustained power dissipation above 350 mW must evaluate thermal management independently.

Q: Are both substitute parts RoHS compliant?

A: Yes. Both the MMBT100 and LP395Z/LFT1 carry ROHS3 compliance certification. The BC548B is classified as RoHS non-compliant. Substitution with either device addresses RoHS compliance requirements for new designs or procurement initiatives.

Q: What is the collector current capacity difference between the BC548B and substitutes?

A: The BC548B is rated for 100 mA maximum collector current. The MMBT100 supports 500 mA, providing five times the current capacity. The LP395Z/LFT1 collector current specification is not provided in the available documentation. Applications requiring collector currents above 100 mA benefit from MMBT100 selection.

Q: Can both substitutes be used interchangeably in the same design?

A: No. The MMBT100 and LP395Z/LFT1 use different package formats (surface mount versus through hole) and have different electrical specifications. Selection depends on circuit board technology, thermal requirements, and specific application parameters. Each substitute is suitable for different implementation scenarios.