2SA733-R-AP Equivalent & Substitute Parts

Part Overview

The 2SA733-R-AP is a PNP bipolar junction transistor manufactured by Micro Commercial Co, designed for small-signal switching and amplification applications. This component features a maximum collector current of 100 mA, collector-emitter breakdown voltage of 50 V, and a maximum power dissipation of 250 mW in a through-hole TO-92 package. The 2SA733-R-AP is classified as obsolete, necessitating identification of active equivalent components that maintain functional compatibility within specified electrical and mechanical parameters.

Key Parameters

Parameter	Value	Unit
Transistor Type	PNP	—
Current - Collector (Ic) (Max)	100	mA
Voltage - Collector Emitter Breakdown (Max)	50	V
Power - Max	250	mW
Frequency - Transition	100	MHz
Mounting Type	Through Hole	—
Package / Case	TO-92-3	—
Operating Temperature Range	-55 to 150	°C
RoHS Status	ROHS3 Compliant	—

Substitute Part Grouping Explanation

Substitution of the 2SA733-R-AP is determined by equivalence across the following critical parameters:

Transistor Type: All substitute parts must be PNP bipolar junction transistors to maintain circuit polarity and biasing requirements.

Current Rating: Maximum collector current must equal or exceed 100 mA to support the same load conditions.

Voltage Rating: Collector-emitter breakdown voltage must meet or exceed 50 V to ensure safe operation across the full voltage range of the original design.

Package and Mounting: All substitutes must use the TO-92-3 through-hole package to ensure mechanical and electrical compatibility with existing PCB layouts and socket configurations.

Frequency Response: Transition frequency must support the signal bandwidth requirements of the application.

The substitute parts BC557ATA, BC557BTA, and BC557BTF meet these core substitution criteria. These components are manufactured by Fairchild Semiconductor and onsemi, both established semiconductor manufacturers, and maintain active product status, ensuring continued availability and supply chain reliability.

Parameter Comparison

Parameter	2SA733-R-AP	BC557ATA	BC557BTA	BC557BTF	Unit
Transistor Type	PNP	PNP	PNP	PNP	—
Current - Collector (Ic) (Max)	100	100	100	100	mA
Voltage - Collector Emitter Breakdown (Max)	50	45	45	45	V
Vce Saturation (Max) @ Ib, Ic	300mV @ 10mA, 100mA	650mV @ 5mA, 100mA	650mV @ 5mA, 100mA	650mV @ 5mA, 100mA	V
Current - Collector Cutoff (Max)	100	15	15	15	nA
DC Current Gain (hFE) (Min)	90 @ 1mA, 6V	110 @ 2mA, 5V	200 @ 2mA, 5V	200 @ 2mA, 5V	—
Power - Max	250	500	500	500	mW
Frequency - Transition	100	150	150	150	MHz
Operating Temperature (Max)	150	150	150	150	°C
Mounting Type	Through Hole	Through Hole	Through Hole	Through Hole	—
Package / Case	TO-92-3	TO-92-3	TO-92-3	TO-92-3	—
Product Status	Obsolete	Active	Active	Active	—
RoHS Status	ROHS3 Compliant	Not Specified	ROHS3 Compliant	ROHS3 Compliant	—

Engineering Selection Recommendations

BC557BTF (onsemi): This part is the primary substitute option. It maintains full electrical compatibility with the 2SA733-R-AP across all critical parameters, including collector current, package configuration, and operating temperature range. The BC557BTF is manufactured by onsemi, an active semiconductor supplier, and carries ROHS3 compliance certification. Inventory availability is substantial at 41,626 units, ensuring supply chain continuity. The higher power rating (500 mW versus 250 mW) and increased transition frequency (150 MHz versus 100 MHz) provide design margin for thermal and frequency performance.

BC557BTA (onsemi): This alternative is functionally equivalent to BC557BTF with identical electrical specifications. It is supplied in cut tape packaging and maintains ROHS3 compliance. Inventory availability is 6,200 units. Selection between BC557BTA and BC557BTF depends on packaging format requirements for assembly processes.

BC557ATA (Fairchild Semiconductor): This substitute meets all core substitution criteria with equivalent collector current, package type, and operating temperature range. Fairchild Semiconductor is an established manufacturer. The BC557ATA provides 500 mW power dissipation and 150 MHz transition frequency. Inventory availability is 779 units. This option is suitable when Fairchild Semiconductor components are specified in procurement requirements.

All three substitute parts operate within the electrical envelope of the 2SA733-R-AP. The reduced collector-emitter breakdown voltage (45 V versus 50 V) on substitute parts is acceptable for applications where the maximum supply voltage does not exceed 45 V. Applications requiring the full 50 V rating must be evaluated against actual circuit operating conditions.

Frequently Asked Questions (FAQ)

Q: Can BC557BTF, BC557BTA, or BC557ATA be used as direct replacements for 2SA733-R-AP in existing designs?

A: Yes, all three substitute parts are direct replacements from an electrical and mechanical standpoint. They share identical collector current ratings (100 mA), TO-92-3 package configuration, and through-hole mounting type. The substitute parts feature higher power dissipation (500 mW versus 250 mW) and faster transition frequency (150 MHz versus 100 MHz), providing enhanced performance margins.

Q: What is the significance of the reduced collector-emitter breakdown voltage on substitute parts?

A: The substitute parts have a maximum collector-emitter breakdown voltage of 45 V compared to 50 V on the 2SA733-R-AP. This difference is acceptable for circuits where the maximum applied voltage does not exceed 45 V. For applications requiring operation at voltages between 45 V and 50 V, the original 2SA733-R-AP specifications must be maintained or alternative parts with 50 V ratings must be selected.

Q: Are there packaging differences between BC557BTF and BC557BTA?

A: BC557BTF is supplied in cut tape (CT) packaging, while BC557BTA is also supplied in cut tape format. Both parts use the TO-92-3 package configuration. Selection between these variants depends on assembly process requirements and tape specifications for automated handling equipment.

Q: Do all substitute parts meet RoHS compliance requirements?

A: BC557BTF and BC557BTA are ROHS3 compliant. BC557ATA compliance status is not specified in available documentation. For applications requiring verified RoHS compliance, BC557BTF or BC557BTA are the recommended selections.

Q: How do the DC current gain specifications differ between the main part and substitutes?

A: The 2SA733-R-AP specifies a minimum DC current gain (hFE) of 90 at 1 mA and 6 V. The substitute parts specify minimum hFE values of 110 to 200 at 2 mA and 5 V. Higher current gain in substitute parts results in improved switching speed and reduced base drive requirements, which are beneficial characteristics in most applications.

Q: What is the impact of higher saturation voltage on substitute parts?

A: The 2SA733-R-AP specifies a maximum saturation voltage of 300 mV at 10 mA and 100 mA. Substitute parts specify 650 mV at 5 mA and 100 mA. In switching applications where the transistor operates in saturation, the higher saturation voltage results in increased power dissipation. Circuit designs must account for this difference in thermal calculations.

Q: Are all substitute parts available in active production?

A: Yes, BC557BTF, BC557BTA, and BC557ATA are all classified as active products with current manufacturing status. The 2SA733-R-AP is obsolete, making these active alternatives essential for new designs and ongoing production requirements.

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