BC557B Equivalent & Substitute Parts

Part Overview

The BC557B is a PNP bipolar junction transistor manufactured by onsemi, housed in a TO-92 through-hole package. This component is rated for 45 V collector-emitter breakdown voltage and 100 mA maximum collector current, with a maximum power dissipation of 625 mW. The BC557B is classified as obsolete, which necessitates identification of active equivalent parts for new designs and ongoing production requirements. Substitute parts must maintain electrical and mechanical compatibility while meeting current manufacturing and compliance standards.

Substiute Parts

BC557B

onsemiIn Stock: 7098BC557B Datasheet

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BC557BTA

onsemiIn Stock: 6210BC557BTA Datasheet

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BC557BTF

onsemiIn Stock: 41658BC557BTF Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the BC557B are identified based on strict electrical and mechanical parameter matching within the allowed specifications for PNP bipolar junction transistors in the TO-92 package category. The substitution criteria are:

Electrical Parameters (Must Match or Exceed):

• Transistor Type: PNP
• Current - Collector (Ic) Max: 100 mA minimum
• Voltage - Collector Emitter Breakdown: 45 V minimum
• Vce Saturation: 650 mV @ 5 mA, 100 mA
• DC Current Gain (hFE): 180 minimum @ 2 mA, 5 V
• Operating Temperature: -55°C to 150°C minimum

Mechanical Parameters (Must Match):

• Mounting Type: Through Hole
• Package / Case: TO-92-3 (TO-226)

The substitute parts BC557BTA and BC557BTF meet all electrical and mechanical requirements. Both parts share the same base product number (BC557) and are manufactured by onsemi, confirming design compatibility within the BC557 family.

Parameter Comparison

Engineering Selection Recommendations

BC557BTA and BC557BTF are direct functional equivalents to the BC557B for applications requiring PNP bipolar junction transistor operation within the specified electrical and mechanical parameters.

Product Status Consideration: The BC557B is classified as obsolete. Both BC557BTA and BC557BTF are active products, ensuring continued availability and manufacturing support for new designs and production continuity.

Compliance Consideration: BC557BTA and BC557BTF are ROHS3 compliant, whereas the BC557B is non-compliant. For applications subject to RoHS regulations, BC557BTA or BC557BTF must be selected.

Electrical Performance: BC557BTA and BC557BTF provide equivalent or superior electrical characteristics. Both parts deliver DC current gain (hFE) of 200 @ 2 mA, 5 V, exceeding the BC557B minimum of 180. Collector cutoff current is reduced to 15 nA compared to 100 nA in the BC557B, indicating improved leakage performance.

Power Dissipation: BC557BTA and BC557BTF are rated for 500 mW maximum power dissipation, compared to 625 mW for the BC557B. Applications requiring power dissipation above 500 mW must be evaluated against actual circuit requirements.

Frequency Response: BC557BTA and BC557BTF operate at 150 MHz transition frequency, compared to 320 MHz for the BC557B. Applications requiring transition frequencies above 150 MHz must retain the BC557B or identify alternative parts with higher frequency specifications.

Packaging: BC557BTA and BC557BTF are supplied in Cut Tape (CT) packaging, whereas BC557B inventory is in bulk form. Packaging format selection depends on procurement and assembly requirements.

Frequently Asked Questions (FAQ)

Q: Can BC557BTA or BC557BTF be used as direct replacements for BC557B in existing designs?

A: BC557BTA and BC557BTF are electrically and mechanically compatible with BC557B for applications operating within 500 mW power dissipation and 150 MHz frequency requirements. The TO-92-3 package pinout is identical. Verify that your circuit does not require the higher power rating (625 mW) or transition frequency (320 MHz) of the BC557B before substitution.

Q: What is the difference between BC557BTA and BC557BTF?

A: BC557BTA and BC557BTF are identical in electrical specifications and package type. Both are manufactured by onsemi, rated for 45 V, 100 mA, and 500 mW. The primary difference is packaging format: BC557BTA and BC557BTF are both supplied in Cut Tape (CT). Inventory availability may differ between the two part numbers.

Q: Are BC557BTA and BC557BTF RoHS compliant?

A: Yes, both BC557BTA and BC557BTF are ROHS3 compliant. The BC557B is RoHS non-compliant. For applications subject to RoHS regulations, BC557BTA or BC557BTF must be selected.

Q: What is the operating temperature range for BC557BTA and BC557BTF?

A: BC557BTA and BC557BTF are rated for a maximum junction temperature (TJ) of 150°C. The BC557B specifies an operating temperature range of -55°C to 150°C. Verify that your application does not require operation below ambient temperature conditions before substitution.

Q: Can I use BC557BTA or BC557BTF in high-frequency applications?

A: BC557BTA and BC557BTF are rated for 150 MHz transition frequency. If your application requires operation above 150 MHz, the BC557B (320 MHz) or alternative parts with higher frequency specifications must be used.

Q: What is the maximum power dissipation for BC557BTA and BC557BTF?

A: BC557BTA and BC557BTF are rated for 500 mW maximum power dissipation. The BC557B is rated for 625 mW. If your circuit requires power dissipation above 500 mW, verify that BC557BTA or BC557BTF can operate within your thermal design before substitution.

Q: Are the TO-92-3 packages of BC557B, BC557BTA, and BC557BTF physically identical?

A: BC557B uses TO-92-3 (TO-226) Long Body package. BC557BTA and BC557BTF use TO-92-3 (TO-226AA) Formed Leads package. Both are through-hole TO-92 variants with identical pinout and are mechanically compatible for PCB assembly. Verify lead forming specifications if precision lead placement is required.

Q: What is the DC current gain (hFE) specification for each part?

A: BC557B specifies minimum hFE of 180 @ 2 mA, 5 V. BC557BTA and BC557BTF specify minimum hFE of 200 @ 2 mA, 5 V. Both substitute parts provide equal or superior current gain performance.