BC640-AP Equivalent & Substitute Parts

Part Overview

The BC640-AP is a PNP bipolar junction transistor manufactured by Micro Commercial Co, designed for general-purpose switching and amplification applications. It features a maximum collector current of 1 A, collector-emitter breakdown voltage of 100 V, and a power dissipation rating of 830 mW in a Through Hole TO-92 package. The BC640-AP is classified as an obsolete product, necessitating identification of active equivalent parts for new designs and ongoing production requirements. Substitute parts must maintain electrical compatibility within the specified parameter ranges while offering current manufacturing availability and active product status.

Key Parameters

Parameter	Value	Unit
Transistor Type	PNP	—
Current - Collector (Ic) (Max)	1	A
Voltage - Collector Emitter Breakdown (Max)	100	V
Vce Saturation (Max) @ Ib, Ic	500mV @ 50mA, 500mA	—
Current - Collector Cutoff (Max)	100	nA
DC Current Gain (hFE) (Min) @ Ic, Vce	100 @ 150mA, 2V	—
Power - Max	830	mW
Frequency - Transition	100	MHz
Operating Temperature	-65 to 150	°C
Mounting Type	Through Hole	—
Package / Case	TO-92-3	—
RoHS Status	ROHS3 Compliant	—

Substitute Part Grouping Explanation

Substitution of the BC640-AP is determined by strict equivalence across the following critical electrical and mechanical parameters:

Electrical Compatibility Criteria:

Transistor polarity must remain PNP
Maximum collector current must equal or exceed 1 A
Collector-emitter breakdown voltage must equal or exceed 100 V
Saturation voltage characteristics must match at specified base and collector currents
Collector cutoff current must not exceed 100 nA
Transition frequency must equal or exceed 100 MHz
Power dissipation rating must support 830 mW or greater

Mechanical Compatibility Criteria:

Package type must be TO-92-3 (Through Hole)
Formed leads configuration must be compatible with existing PCB layouts

Compliance Criteria:

RoHS3 compliance is required
Product status should be Active for ongoing availability

The BC640TA from onsemi meets the mechanical and compliance requirements but operates within reduced electrical specifications. Substitution is valid only when application requirements do not demand the full 100 V breakdown voltage specification of the original part.

Parameter Comparison

Parameter	BC640-AP (Main Part)	BC640TA (Substitute)	Compatibility Notes
Manufacturer	Micro Commercial Co	onsemi	Different manufacturer
Transistor Type	PNP	PNP	Matched
Current - Collector (Ic) (Max)	1 A	1 A	Matched
Voltage - Collector Emitter Breakdown (Max)	100 V	80 V	Substitute rated lower; acceptable for applications ≤80 V
Vce Saturation (Max) @ Ib, Ic	500mV @ 50mA, 500mA	500mV @ 50mA, 500mA	Matched
Current - Collector Cutoff (Max)	100 nA	100 nA	Matched
DC Current Gain (hFE) (Min) @ Ic, Vce	100 @ 150mA, 2V	40 @ 150mA, 2V	Substitute has lower gain; acceptable for applications not requiring minimum 100 hFE
Power - Max	830 mW	1 W	Substitute rated higher; compatible
Frequency - Transition	100 MHz	100 MHz	Matched
Operating Temperature (Max)	150°C	150°C	Matched
Mounting Type	Through Hole	Through Hole	Matched
Package / Case	TO-92-3	TO-92-3	Matched
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	Matched
Product Status	Obsolete	Active	Substitute is actively manufactured

Engineering Selection Recommendations

BC640TA Selection Criteria:

The BC640TA from onsemi is a valid substitute for the BC640-AP in applications where the following conditions are satisfied:

Voltage Rating Requirement: The circuit design operates at collector-emitter voltages not exceeding 80 V. Applications requiring the full 100 V breakdown voltage specification of the BC640-AP cannot use the BC640TA.
Current Gain Requirement: The circuit design does not require a minimum DC current gain (hFE) of 100 at 150 mA and 2 V. The BC640TA provides a minimum hFE of 40 at these conditions, which is acceptable for circuits designed with lower gain specifications or with appropriate base drive compensation.
Compliance and Availability: The BC640TA maintains ROHS3 compliance and is actively manufactured, providing long-term supply chain reliability compared to the obsolete BC640-AP.
Mechanical Compatibility: Both parts use identical TO-92-3 package geometry with formed leads, ensuring direct PCB layout compatibility without redesign.
Thermal Performance: The BC640TA provides superior power dissipation capability (1 W versus 830 mW), offering additional thermal margin in applications operating near maximum power ratings.

Frequently Asked Questions (FAQ)

Q: Can the BC640TA directly replace the BC640-AP in all applications?

A: No. The BC640TA has a reduced collector-emitter breakdown voltage rating of 80 V compared to the BC640-AP's 100 V. Direct substitution is valid only for circuits operating at voltages not exceeding 80 V. Applications requiring the full 100 V specification must use alternative parts or the original BC640-AP if available.

Q: What is the significance of the different DC current gain (hFE) specifications?

A: The BC640-AP specifies a minimum hFE of 100 at 150 mA and 2 V, while the BC640TA specifies a minimum of 40 at the same conditions. This difference affects base drive requirements and circuit biasing. Circuits designed for the lower gain of the BC640TA will function correctly. Circuits requiring the higher gain of the BC640-AP may require base drive circuit modifications if using the BC640TA.

Q: Are the packages physically identical?

A: Yes. Both the BC640-AP and BC640TA use the TO-92-3 package with formed leads. No PCB layout modifications are required for mechanical compatibility. Pin assignments and lead spacing are identical.

Q: Does the BC640TA meet RoHS compliance requirements?

A: Yes. The BC640TA is ROHS3 compliant, matching the compliance status of the BC640-AP. Both parts are suitable for applications with RoHS requirements.

Q: What is the advantage of the BC640TA's higher power rating?

A: The BC640TA is rated for 1 W maximum power dissipation compared to the BC640-AP's 830 mW. This provides additional thermal headroom in applications operating near maximum power levels, reducing junction temperature and extending component life in thermally constrained designs.

Q: Is the BC640TA actively manufactured?

A: Yes. The BC640TA is classified as an Active product, ensuring ongoing availability and supply chain continuity. The BC640-AP is obsolete, making the BC640TA the preferred choice for new designs and production continuity.

Q: What should be verified before substituting the BC640TA for the BC640-AP?

A: Confirm that the application circuit operates at collector-emitter voltages not exceeding 80 V and that the circuit design accommodates the BC640TA's minimum hFE of 40. Verify that the base drive circuit provides sufficient current for proper transistor operation at the lower gain specification.

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