BC858A-7-F Equivalent & Substitute Parts

Part Overview

The BC858A-7-F is a PNP bipolar junction transistor manufactured by Diodes Incorporated, rated for 30 V collector-emitter breakdown voltage and 100 mA maximum collector current. The device is packaged in SOT-23-3 surface mount configuration with a maximum power dissipation of 300 mW and transition frequency of 200 MHz. This part is classified as obsolete, necessitating identification of active equivalent and substitute components for ongoing design requirements and procurement continuity.

Key Parameters

Parameter	Value	Unit
Transistor Type	PNP	—
Collector Current (Max)	100	mA
Collector-Emitter Breakdown Voltage (Max)	30	V
Power Dissipation (Max)	300	mW
Transition Frequency	200	MHz
Vce Saturation @ Ib, Ic	650 mV @ 5 mA, 100 mA	—
DC Current Gain (hFE) @ Ic, Vce	125 @ 2 mA, 5 V	—
Operating Temperature Range	−65 to 150	°C
Package Type	SOT-23-3	—
Mounting Type	Surface Mount	—

Substitute Part Grouping Explanation

Substitution of the BC858A-7-F is determined by the following critical parameters:

Direct Electrical Equivalents (identical or superior ratings within the same package family):

Collector current rating: 100 mA minimum
Collector-emitter breakdown voltage: 30 V minimum
Package type: SOT-23-3 compatible
Mounting type: Surface mount
Transistor polarity: PNP

Higher Current Capacity Substitutes (same voltage rating, increased current handling):

Collector current rating: 700 mA to 3 A
Collector-emitter breakdown voltage: 30 V
Package types: SOT-23-3, TSMT3, or 3-CPH
Mounting type: Surface mount
Transistor polarity: PNP

Enhanced Voltage Rating Substitutes (higher voltage tolerance, same current):

Collector current rating: 100 mA
Collector-emitter breakdown voltage: 45 V or higher
Package type: SOT-23-3
Mounting type: Surface mount
Transistor polarity: PNP

Parameter Comparison

Part Number	Manufacturer	Ic (Max) mA	Vce(br) V	Power mW	fT MHz	Package	Status
BC858A-7-F	Diodes Inc.	100	30	300	200	SOT-23-3	Obsolete
BC857A-7-F	Diodes Inc.	100	45	300	200	SOT-23-3	Active
BC858ALT1G	onsemi	100	30	300	100	SOT-23-3	Active
BC858A RFG	Taiwan Semiconductor	100	30	200	100	SOT-23-3	Active
2STR2230	STMicroelectronics	1500	30	500	100	SOT-23-3	Active
2SB1695KT146	Rohm Semiconductor	1500	30	200	280	SMT3	Active
2SB1695TL	Rohm Semiconductor	1500	30	500	280	TSMT3	Active
2SB1706TL	Rohm Semiconductor	2000	30	500	280	TSMT3	Active
2SB1708TL	Rohm Semiconductor	3000	30	500	200	TSMT3	Active
2SB1710TL	Rohm Semiconductor	1000	30	500	320	TSMT3	Active
30A02CH-TL-E	onsemi	700	30	700	520	3-CPH	Active

Engineering Selection Recommendations

Direct Replacement (Pin-Compatible, Same Electrical Class):

BC858ALT1G (onsemi) and BC858A RFG (Taiwan Semiconductor) are direct replacements for the BC858A-7-F. Both maintain the 100 mA collector current rating, 30 V breakdown voltage, and SOT-23-3 package configuration. Both parts are active products with ROHS3 compliance and unlimited moisture sensitivity rating. The BC858ALT1G operates at 100 MHz transition frequency compared to the original 200 MHz specification. The BC858A RFG similarly operates at 100 MHz with reduced power dissipation of 200 mW.

Enhanced Voltage Rating Alternative:

BC857A-7-F (Diodes Incorporated) provides identical electrical performance to the BC858A-7-F with the exception of an increased collector-emitter breakdown voltage rating of 45 V versus 30 V. This part is active and maintains SOT-23-3 packaging, ROHS3 compliance, and unlimited moisture sensitivity. Selection of this part is appropriate for applications requiring higher voltage margin.

Higher Current Capacity Alternatives (Same Package Family):

2STR2230 (STMicroelectronics) is a 1.5 A rated PNP transistor in SOT-23-3 package with 30 V breakdown voltage and 500 mW power dissipation. This part is active with ROHS3 compliance and operates at 100 MHz transition frequency. Direct pin compatibility with SOT-23-3 footprint is maintained.

Higher Current Capacity Alternatives (Alternative Packages):

2SB1695TL, 2SB1706TL, 2SB1708TL, and 2SB1710TL (Rohm Semiconductor) are PNP transistors with 30 V breakdown voltage and TSMT3 surface mount packaging. These parts provide collector current ratings from 1 A to 3 A with 500 mW power dissipation and transition frequencies from 200 MHz to 320 MHz. All are active products with ROHS3 compliance.

30A02CH-TL-E (onsemi) is a 700 mA rated PNP transistor in 3-CPH surface mount package with 30 V breakdown voltage, 700 mW power dissipation, and 520 MHz transition frequency. This part is active with ROHS3 compliance.

All substitute parts listed are active products with ROHS3 compliance, REACH unaffected status, and unlimited moisture sensitivity rating (MSL 1).

Frequently Asked Questions (FAQ)

Q: Can BC858ALT1G be used as a direct replacement for BC858A-7-F?

A: Yes. BC858ALT1G maintains identical collector current (100 mA), collector-emitter breakdown voltage (30 V), and SOT-23-3 package configuration. The transition frequency is reduced from 200 MHz to 100 MHz. Verify that the application does not require the higher frequency specification before substitution.

Q: What is the difference between BC858A-7-F and BC857A-7-F?

A: The primary difference is the collector-emitter breakdown voltage rating. BC857A-7-F is rated for 45 V compared to 30 V for BC858A-7-F. All other electrical parameters, including collector current (100 mA), power dissipation (300 mW), and transition frequency (200 MHz), are identical. BC857A-7-F is suitable for applications requiring higher voltage tolerance.

Q: Can higher current rated parts like 2STR2230 or 2SB1695TL replace BC858A-7-F?

A: Yes, from an electrical compatibility standpoint. These parts maintain the 30 V breakdown voltage and SOT-23-3 or equivalent surface mount packaging. However, verify that the application circuit design does not depend on the specific 100 mA current limitation of the original part. Higher current capacity parts will operate correctly in circuits designed for lower current devices.

Q: Are all substitute parts RoHS compliant?

A: Yes. All substitute parts listed are ROHS3 compliant and REACH unaffected, matching the compliance status of the BC858A-7-F.

Q: What is the significance of the different package designations (SOT-23-3, TSMT3, 3-CPH)?

A: These designations indicate different surface mount package physical configurations. SOT-23-3 is a three-lead small outline transistor package. TSMT3 is a larger surface mount package with higher power dissipation capability. 3-CPH is a three-contact power housing package. Parts with different package designations require different PCB footprints and cannot be used as direct pin-for-pin replacements without PCB redesign.

Q: Which substitute part should be selected for a new design?

A: For new designs requiring the same electrical specifications as BC858A-7-F, select BC858ALT1G (onsemi) or BC858A RFG (Taiwan Semiconductor) as both are active products with identical ratings and SOT-23-3 packaging. For applications requiring higher voltage tolerance, select BC857A-7-F. For applications requiring higher current capacity, select 2STR2230 (SOT-23-3 package) or the Rohm Semiconductor TSMT3 series (2SB1695TL, 2SB1706TL, 2SB1708TL, 2SB1710TL) based on specific current requirements.

Q: What is the operating temperature range for substitute parts?

A: BC858ALT1G and BC858A RFG operate from −55°C to 150°C. BC857A-7-F operates from −65°C to 150°C, matching the original BC858A-7-F specification. Rohm Semiconductor and STMicroelectronics parts operate at 150°C maximum junction temperature. Verify application temperature requirements before final part selection.

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