BC556TF Equivalent & Substitute Parts

Part Overview

The BC556TF is a PNP bipolar junction transistor manufactured by onsemi, designed for small-signal switching and amplification applications. This device features a maximum collector current of 100 mA, collector-emitter breakdown voltage of 65 V, and a transition frequency of 150 MHz. The BC556TF is currently classified as obsolete, which necessitates identification of equivalent substitute components for ongoing design support and procurement continuity. Substitute parts maintain identical or superior electrical and mechanical specifications while offering improved availability or product status.

Key Parameters

Parameter	Value	Unit
Transistor Type	PNP	—
Current - Collector (Ic) Max	100	mA
Voltage - Collector Emitter Breakdown (Max)	65	V
Vce Saturation (Max)	650	mV @ 5mA, 100mA
Current - Collector Cutoff (Max)	15	nA
DC Current Gain (hFE) Min	110	@ 2mA, 5V
Power - Max	500	mW
Frequency - Transition	150	MHz
Operating Temperature (TJ)	150	°C
Mounting Type	Through Hole	—
Package / Case	TO-92-3	—

Substitute Part Grouping Explanation

Substitute parts for the BC556TF are qualified based on strict electrical and mechanical parameter equivalence. The substitution criteria are:

Electrical Parameters (Must Match or Exceed):

Transistor Type: PNP
Current - Collector (Ic) Max: 100 mA minimum
Voltage - Collector Emitter Breakdown: 65 V minimum
Vce Saturation: 650 mV maximum @ 5mA, 100mA
Current - Collector Cutoff: 15 nA maximum
Power - Max: 500 mW minimum
Frequency - Transition: 150 MHz minimum
Operating Temperature: 150°C minimum

Mechanical Parameters (Must Match):

Mounting Type: Through Hole
Package / Case: TO-92-3

All substitute parts listed maintain these specifications and are therefore electrically and mechanically interchangeable with the BC556TF in circuit applications.

Parameter Comparison

Parameter	BC556TF (onsemi)	BC556ATA (onsemi)	BC556BTA (Fairchild)
Transistor Type	PNP	PNP	PNP
Current - Collector (Ic) Max	100 mA	100 mA	100 mA
Voltage - Collector Emitter Breakdown (Max)	65 V	65 V	65 V
Vce Saturation (Max) @ Ib, Ic	650 mV @ 5mA, 100mA	650 mV @ 5mA, 100mA	650 mV @ 5mA, 100mA
Current - Collector Cutoff (Max)	15 nA	15 nA	15 nA
DC Current Gain (hFE) Min @ Ic, Vce	110 @ 2mA, 5V	110 @ 2mA, 5V	200 @ 2mA, 5V
Power - Max	500 mW	500 mW	500 mW
Frequency - Transition	150 MHz	150 MHz	150 MHz
Operating Temperature (TJ)	150°C	150°C	150°C
Mounting Type	Through Hole	Through Hole	Through Hole
Package / Case	TO-92-3	TO-92-3	TO-92-3
Product Status	Obsolete	Last Time Buy	Active

Engineering Selection Recommendations

BC556ATA (onsemi): This part is a direct equivalent to the BC556TF with identical electrical specifications and TO-92-3 packaging. The BC556ATA is classified as Last Time Buy, indicating limited future availability. This part is ROHS3 compliant and suitable for applications requiring onsemi sourcing continuity. Inventory availability is significantly higher than the BC556TF.

BC556BTA (Fairchild Semiconductor): This part meets all electrical and mechanical substitution criteria with identical core parameters. The BC556BTA is classified as Active, ensuring long-term availability and supply chain stability. The DC Current Gain (hFE) minimum specification is 200 @ 2mA, 5V, which exceeds the BC556TF requirement of 110, providing superior current amplification characteristics. This part is recommended for new designs and applications requiring extended product lifecycle support.

Both substitute parts are electrically and mechanically compatible with the BC556TF and support direct pin-for-pin replacement in existing circuit designs.

Frequently Asked Questions (FAQ)

Q: Can BC556ATA be used as a direct replacement for BC556TF?

A: Yes. The BC556ATA maintains identical electrical specifications including collector current, breakdown voltage, saturation voltage, and transition frequency. Both parts use the TO-92-3 package with through-hole mounting. Pin configuration is identical, enabling direct substitution.

Q: What is the difference between BC556ATA and BC556BTA?

A: Both parts meet the BC556TF electrical and mechanical specifications. The primary difference is DC Current Gain (hFE): BC556ATA specifies 110 minimum, while BC556BTA specifies 200 minimum. BC556BTA is manufactured by Fairchild Semiconductor and maintains Active product status, whereas BC556ATA is Last Time Buy. For applications sensitive to current gain variation, BC556BTA provides higher guaranteed amplification.

Q: Why is the BC556TF classified as obsolete?

A: The BC556TF is no longer in active production. Substitute parts BC556ATA and BC556BTA provide equivalent functionality with improved availability and product status.

Q: Are there packaging differences between these parts?

A: All three parts use the TO-92-3 package with through-hole mounting. Physical dimensions and pin configurations are identical, supporting direct board-level replacement without layout modifications.

Q: Which substitute part should be selected for new designs?

A: BC556BTA is recommended for new designs due to Active product status, ensuring long-term supply availability and manufacturing support. This part exceeds the minimum DC Current Gain specification, providing design margin for amplification-critical applications.

Q: Can these parts be used interchangeably in existing circuits?

A: Yes. All three parts are electrically and mechanically equivalent within the specified parameters. Circuit performance remains unchanged when substituting BC556TF with BC556ATA or BC556BTA.

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