BC546B-AP Equivalent & Substitute Parts

Part Overview

The BC546B-AP is a small-signal NPN bipolar junction transistor manufactured by Micro Commercial Co, designed for general-purpose switching and amplification applications. This device operates at 65 V collector-emitter breakdown voltage with a maximum collector current of 100 mA and transition frequency of 300 MHz. The BC546B-AP is classified as obsolete, necessitating identification of active equivalent and substitute parts for ongoing design requirements and procurement continuity.

Key Parameters

Parameter	Value	Unit
Transistor Type	NPN	—
Current - Collector (Ic) Max	100	mA
Voltage - Collector Emitter Breakdown (Max)	65	V
DC Current Gain (hFE) Min @ Ic, Vce	200 @ 2mA, 5V	—
Power - Max	625	mW
Frequency - Transition	300	MHz
Operating Temperature	-55 to 150	°C
Mounting Type	Through Hole	—
Package / Case	TO-92-3	—
RoHS Status	ROHS3 Compliant	—

Substitute Part Grouping Explanation

Substitution of the BC546B-AP is determined by strict equivalence across the following critical parameters:

Primary Substitution Criteria:

Transistor Type: NPN
Current - Collector (Ic) Max: 100 mA
Voltage - Collector Emitter Breakdown (Max): 65 V
DC Current Gain (hFE) Min @ Ic, Vce: 200 @ 2mA, 5V (minimum)
Frequency - Transition: 300 MHz
Mounting Type: Through Hole
Package / Case: TO-92-3

Direct Equivalent: BC546-AP (Micro Commercial Co) maintains identical electrical specifications and active product status, serving as the primary replacement for the obsolete BC546B-AP.

Compatible Substitutes: BC546BTA, BC546BTF, and BC546CTA (all onsemi manufactured) meet the core electrical requirements of 65 V breakdown voltage, 100 mA collector current, 300 MHz transition frequency, and TO-92-3 packaging. These parts are active products with established supply availability.

Limited Compatibility Substitute: BC547BTA (Fairchild Semiconductor) operates at a reduced collector-emitter breakdown voltage of 45 V, making it suitable only for applications with voltage requirements not exceeding 45 V. All other electrical parameters align with the BC546B-AP specification.

Parameter Comparison

Parameter	BC546B-AP	BC546-AP	BC546BTA	BC546BTF	BC546CTA	BC547BTA
Manufacturer	Micro Commercial Co	Micro Commercial Co	onsemi	onsemi	onsemi	Fairchild Semiconductor
Product Status	Obsolete	Active	Active	Active	Active	Active
Transistor Type	NPN	NPN	NPN	NPN	NPN	NPN
Current - Collector (Ic) Max	100 mA	100 mA	100 mA	100 mA	100 mA	100 mA
Voltage - Collector Emitter Breakdown (Max)	65 V	65 V	65 V	65 V	65 V	45 V
Vce Saturation (Max) @ Ib, Ic	300mV @ 5mA, 100mA	300mV @ 5mA, 100mA	600mV @ 5mA, 100mA	600mV @ 5mA, 100mA	600mV @ 5mA, 100mA	600mV @ 5mA, 100mA
DC Current Gain (hFE) Min @ Ic, Vce	200 @ 2mA, 5V	200 @ 2mA, 5V	200 @ 2mA, 5V	200 @ 2mA, 5V	420 @ 2mA, 5V	200 @ 2mA, 5V
Power - Max	625 mW	625 mW	500 mW	500 mW	500 mW	625 mW
Frequency - Transition	300 MHz	300 MHz	300 MHz	300 MHz	300 MHz	300 MHz
Operating Temperature	-55 to 150°C	-55 to 150°C	150°C	150°C	150°C	-55 to 150°C
Mounting Type	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole
Package / Case	TO-92-3	TO-92-3	TO-92-3	TO-92-3	TO-92-3	TO-92-3
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	Not specified

Engineering Selection Recommendations

Primary Selection: BC546-AP (Micro Commercial Co) is the recommended direct replacement for BC546B-AP. This part maintains identical electrical specifications, active product status, and ROHS3 compliance. The transition from obsolete to active status ensures long-term supply availability and procurement stability.

Secondary Selection: BC546BTA, BC546BTF, and BC546CTA (onsemi) are functionally compatible substitutes meeting all core electrical requirements. These parts are manufactured by onsemi, an established semiconductor supplier with active product status. BC546CTA offers higher DC current gain (420 vs. 200 @ 2mA, 5V), which may provide design flexibility in gain-sensitive applications. All three onsemi variants are ROHS3 compliant.

Conditional Selection: BC547BTA (Fairchild Semiconductor) operates at 45 V maximum collector-emitter breakdown voltage, 20 V below the BC546B-AP specification. This part is suitable only for circuit designs with voltage requirements not exceeding 45 V. BC547BTA maintains 100 mA collector current, 300 MHz transition frequency, and TO-92-3 packaging compatibility.

Compliance Considerations: All recommended substitutes maintain ROHS3 compliance and REACH unaffected status, consistent with the original BC546B-AP specification. Moisture sensitivity level (MSL) is not applicable for onsemi and Fairchild variants, compared to MSL 1 (Unlimited) for Micro Commercial Co parts.

Frequently Asked Questions (FAQ)

Q: Can BC546-AP directly replace BC546B-AP in existing designs?

A: Yes. BC546-AP is the direct equivalent, maintaining identical electrical specifications including 65 V breakdown voltage, 100 mA collector current, 300 MHz transition frequency, and TO-92-3 packaging. The primary difference is product status: BC546-AP is active while BC546B-AP is obsolete.

Q: What is the difference between BC546BTA and BC546BTF?

A: BC546BTA and BC546BTF are functionally equivalent onsemi products with identical electrical specifications. Both operate at 65 V breakdown voltage, 100 mA collector current, and 300 MHz transition frequency. The designation suffix indicates different manufacturing or packaging batches. Both are active products with established supply availability.

Q: Why does BC546CTA have a higher DC current gain (420 vs. 200)?

A: BC546CTA is classified as a "C" grade transistor, indicating higher DC current gain specification compared to the "B" grade BC546B-AP and BC546BTA. This higher gain may be advantageous in applications requiring increased amplification or reduced base drive current. Both grades maintain the same 65 V breakdown voltage and 100 mA collector current.

Q: Is BC547BTA a suitable replacement for BC546B-AP?

A: BC547BTA is a limited compatibility substitute. It operates at 45 V maximum collector-emitter breakdown voltage, compared to 65 V for BC546B-AP. BC547BTA is suitable only for applications with voltage requirements not exceeding 45 V. All other electrical parameters (100 mA collector current, 300 MHz transition frequency, TO-92-3 packaging) are compatible.

Q: What is the significance of the TO-92-3 package designation?

A: TO-92-3 is a three-lead through-hole package standard for small-signal transistors. All substitute parts listed maintain this package format, ensuring mechanical and electrical compatibility with existing PCB layouts and socket configurations. The package accommodates base, collector, and emitter leads in the standard TO-92 form factor.

Q: Are there differences in power dissipation between BC546B-AP and the onsemi substitutes?

A: Yes. BC546B-AP and BC546-AP are rated at 625 mW maximum power dissipation. BC546BTA, BC546BTF, and BC546CTA (onsemi) are rated at 500 mW. This 125 mW difference may be significant in high-power applications. BC547BTA maintains 625 mW rating. Verify application power requirements before selection.

Q: Do all substitute parts have the same operating temperature range?

A: No. BC546B-AP and BC546-AP specify -55°C to 150°C operating temperature. BC546BTA, BC546BTF, and BC546CTA specify 150°C maximum only, without lower temperature specification. BC547BTA maintains -55°C to 150°C range. Verify application temperature requirements, particularly for low-temperature operation.

Q: What is the difference between Vce saturation specifications?

A: BC546B-AP specifies 300 mV maximum Vce saturation at 5 mA base current and 100 mA collector current. All onsemi and Fairchild substitutes specify 600 mV under the same conditions. This 300 mV difference affects switching speed and power dissipation in saturation mode. Applications requiring low saturation voltage should prioritize BC546-AP or BC547BTA.

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