BC858B-HF PNP Bipolar Junction Transistor Equivalent & Substitute Parts

Part Overview

The BC858B-HF is a PNP bipolar junction transistor manufactured by Comchip Technology, designed for small-signal switching and amplification applications. This surface-mount device operates at 30 V maximum collector-emitter breakdown voltage with a maximum collector current of 100 mA and transition frequency of 100 MHz. The part is classified as Active product status with full RoHS3 compliance and unlimited moisture sensitivity rating (MSL 1).

Equivalent and substitute parts are necessary when the primary part becomes unavailable, when alternative packaging formats are required for manufacturing processes, or when design specifications allow for compatible alternatives from different manufacturers that meet the same electrical and mechanical requirements.

Key Parameters

Parameter	BC858B-HF Specification
Transistor Type	PNP
Collector Current (Ic) Maximum	100 mA
Collector-Emitter Breakdown Voltage (Max)	30 V
DC Current Gain (hFE) Min @ Ic, Vce	220 @ 2.2 mA, 5 V
Power Dissipation (Max)	250 mW
Transition Frequency	100 MHz
Operating Temperature Range	-65°C to 150°C (TJ)
Package Type	SOT-23-3 (TO-236-3, SC-59)
Mounting Type	Surface Mount
RoHS Status	RoHS3 Compliant
Moisture Sensitivity Level	1 (Unlimited)

Substitute Part Grouping Explanation

Substitution eligibility for the BC858B-HF is determined by the following critical parameters:

Primary Substitution Criteria:

Transistor type must be PNP
Collector current rating must be ≥ 100 mA
Collector-emitter breakdown voltage must be ≥ 30 V
Package must be SOT-23-3 (TO-236-3, SC-59) or compatible surface-mount equivalent
Operating temperature range must encompass the application requirements
RoHS3 compliance and MSL 1 rating required for standard applications

Secondary Compatibility Factors:

DC current gain (hFE) minimum values may vary within acceptable ranges for the application
Power dissipation ratings of 250 mW or higher are acceptable
Transition frequency of 100 MHz or higher maintains performance compatibility
Vce saturation characteristics must be within specified limits for switching applications

Parts are grouped into three categories based on substitution relationship:

Direct Equivalents: Parts with identical electrical specifications and packaging, differing only in manufacturer or packaging format (tape & reel vs. cut tape).

Manufacturer Recommended Alternatives: Parts from the same base product family (BC858 series variants) that meet or exceed the primary electrical specifications with minor parameter variations acceptable for most applications.

Upgraded Alternatives: Parts with enhanced specifications (higher power rating, higher transition frequency, or automotive qualification) suitable for applications requiring additional performance margin.

Parameter Comparison

Part Number	Manufacturer	Ic (Max)	Vce(BR) (Max)	hFE Min @ Ic, Vce	Power (Max)	Freq (MHz)	Temp Range	Package	Packaging Format
BC858B-HF	Comchip Technology	100 mA	30 V	220 @ 2.2 mA, 5V	250 mW	100	-65 to 150°C	SOT-23-3	Tape & Reel
BC858BLT1G	onsemi	100 mA	30 V	220 @ 2 mA, 5V	300 mW	100	-55 to 150°C	SOT-23-3	Cut Tape & Digi-Reel
BC858BLT3G	onsemi	100 mA	30 V	220 @ 2 mA, 5V	300 mW	100	-55 to 150°C	SOT-23-3	Tape & Reel
BC859B,215	NXP Semiconductors	100 mA	30 V	220 @ 2 mA, 5V	250 mW	100	-55 to 150°C	SOT-23-3	Bulk
BC858A RFG	Taiwan Semiconductor	100 mA	30 V	125 @ 2 mA, 5V	200 mW	100	-55 to 150°C	SOT-23	Tape & Reel
BC858ALT1G	onsemi	100 mA	30 V	125 @ 2 mA, 5V	300 mW	100	-55 to 150°C	SOT-23-3	Cut Tape & Digi-Reel
BC858B RFG	Taiwan Semiconductor	100 mA	30 V	220 @ 2 mA, 5V	200 mW	100	-55 to 150°C	SOT-23	Tape & Reel
BC858C RFG	Taiwan Semiconductor	100 mA	30 V	420 @ 2 mA, 5V	200 mW	100	-55 to 150°C	SOT-23	Tape & Reel
BC858C-7-F	Diodes Incorporated	100 mA	30 V	420 @ 2 mA, 5V	300 mW	200	-65 to 150°C	SOT-23-3	Cut Tape & Digi-Reel
BCW30LT1G	onsemi	100 mA	32 V	215 @ 2 mA, 5V	300 mW	Not specified	-65 to 150°C	SOT-23-3	Tape & Reel
NSVBC858BLT1G	onsemi	100 mA	30 V	220 @ 2 mA, 5V	300 mW	100	-55 to 150°C	SOT-23-3	Tape & Reel

Engineering Selection Recommendations

Direct Substitution (Highest Compatibility):

BC858BLT1G and BC858BLT3G from onsemi are direct functional equivalents with identical electrical specifications to the BC858B-HF. Both parts maintain 100 mA collector current, 30 V breakdown voltage, and 100 MHz transition frequency. The primary difference is packaging format: BC858BLT1G is supplied in cut tape with Digi-Reel format, while BC858BLT3G is supplied in standard tape & reel. Both are RoHS3 compliant with MSL 1 rating. These parts are suitable for direct replacement in manufacturing processes that can accommodate the packaging format change.

NSVBC858BLT1G from onsemi provides identical electrical performance to BC858BLT1G and BC858BLT3G with tape & reel packaging. This part is functionally interchangeable with the original BC858B-HF.

Equivalent Substitution (Electrical Compatibility):

BC859B,215 from NXP Semiconductors meets all primary electrical requirements with 100 mA collector current, 30 V breakdown voltage, and 100 MHz transition frequency. This part is supplied in bulk packaging format and carries automotive qualification (AEC-Q101), making it suitable for applications requiring automotive-grade components. RoHS3 compliance and MSL 1 rating are maintained.

Conditional Substitution (Application-Dependent):

BC858C-7-F from Diodes Incorporated exceeds the original specifications with 200 MHz transition frequency and 300 mW power rating. This part is suitable for applications requiring higher frequency performance or additional thermal margin. The operating temperature range extends to -65°C, matching the original part. RoHS3 compliance and MSL 1 rating are maintained.

BCW30LT1G from onsemi provides a higher collector-emitter breakdown voltage of 32 V with 300 mW power rating. This part is suitable for applications operating at higher supply voltages or requiring additional voltage margin. Operating temperature range extends to -65°C. This part is from a different base product family (BCW30 vs. BC858) but meets all primary substitution criteria.

Lower Performance Alternatives (Reduced Specifications):

BC858A RFG and BC858ALT1G from Taiwan Semiconductor and onsemi respectively feature reduced DC current gain (hFE minimum of 125 vs. 220) and lower power dissipation (200 mW vs. 250 mW). These parts are suitable only for applications where the lower gain and power specifications are acceptable. BC858A RFG is supplied in SOT-23 package (not SOT-23-3), requiring PCB layout verification.

BC858B RFG and BC858C RFG from Taiwan Semiconductor feature reduced power dissipation (200 mW) and are supplied in SOT-23 package format. BC858C RFG provides higher DC current gain (420 vs. 220). These parts require package compatibility verification before selection.

Compliance and Certification:

All listed substitute parts maintain RoHS3 compliance and MSL 1 (unlimited) moisture sensitivity rating, ensuring compatibility with standard manufacturing processes. BC859B,215 carries additional AEC-Q101 automotive qualification for applications requiring automotive-grade components.

Frequently Asked Questions (FAQ)

Q: Can BC858BLT1G and BC858BLT3G be used interchangeably with BC858B-HF?

A: Yes. Both onsemi parts are direct electrical equivalents with identical collector current (100 mA), breakdown voltage (30 V), DC current gain (220 @ 2 mA, 5V), and transition frequency (100 MHz). The difference is packaging format: BC858BLT1G uses cut tape with Digi-Reel format, while BC858BLT3G uses standard tape & reel. Both are RoHS3 compliant with MSL 1 rating. Selection depends on your manufacturing equipment's tape format compatibility.

Q: What is the difference between BC858B-HF and BC858C-7-F?

A: BC858C-7-F from Diodes Incorporated has a higher transition frequency (200 MHz vs. 100 MHz) and higher power dissipation rating (300 mW vs. 250 mW). Both maintain 100 mA collector current and 30 V breakdown voltage. BC858C-7-F is suitable for applications requiring higher frequency performance or additional thermal margin. The DC current gain is higher (420 vs. 220), which may affect circuit biasing in some applications.

Q: Is BCW30LT1G a suitable replacement for BC858B-HF?

A: BCW30LT1G meets the primary substitution criteria with 100 mA collector current, 32 V breakdown voltage (exceeds 30 V requirement), and 300 mW power rating. However, it is from a different base product family (BCW30 vs. BC858). The transition frequency is not specified in the datasheet. This part is suitable for applications where the higher voltage rating is beneficial, but circuit performance should be verified due to the different product family.

Q: Can I use BC859B,215 from NXP in place of BC858B-HF?

A: Yes. BC859B,215 is electrically equivalent with 100 mA collector current, 30 V breakdown voltage, 220 DC current gain, and 100 MHz transition frequency. The primary difference is packaging format (bulk vs. tape & reel). This part carries AEC-Q101 automotive qualification, making it suitable for automotive applications. RoHS3 compliance and MSL 1 rating are maintained.

Q: What are the limitations of BC858A RFG and BC858ALT1G?

A: Both parts have reduced DC current gain (125 vs. 220 minimum) and lower power dissipation (200 mW vs. 250 mW). These specifications may not be suitable for all applications. BC858A RFG is supplied in SOT-23 package (not SOT-23-3), requiring PCB layout verification. These parts are suitable only for applications where the lower gain and power specifications are acceptable.

Q: Are all substitute parts RoHS3 compliant?

A: Yes. All listed substitute parts are RoHS3 compliant with MSL 1 (unlimited) moisture sensitivity rating, ensuring compatibility with standard manufacturing processes and environmental regulations.

Q: What packaging formats are available for BC858B-HF equivalents?

A: Available packaging formats include tape & reel (standard), cut tape with Digi-Reel, and bulk. BC858BLT1G uses cut tape with Digi-Reel format. BC858BLT3G and NSVBC858BLT1G use standard tape & reel. BC859B,215 is supplied in bulk format. Selection depends on your manufacturing equipment's tape handling capability and volume requirements.

Q: Can I substitute BC858B-HF with a higher hFE part like BC858C RFG?

A: BC858C RFG has higher DC current gain (420 vs. 220) and is electrically compatible. However, the higher gain may affect circuit biasing and operating point in some applications. Circuit verification is recommended before substitution. BC858C RFG is supplied in SOT-23 package (not SOT-23-3), requiring PCB layout verification.

Q: What is the temperature range difference between BC858B-HF and substitute parts?

A: BC858B-HF operates from -65°C to 150°C. Most onsemi and NXP substitutes operate from -55°C to 150°C, providing a narrower low-temperature range. BC858C-7-F, BCW30LT1G, and BC858B-HF maintain the full -65°C to 150°C range. For applications requiring operation below -55°C, select parts with the extended temperature range.

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