BC858B Equivalent & Substitute Parts

Part Overview

The BC858B is an active PNP bipolar junction transistor (BJT) manufactured by Infineon Technologies in the SOT-23-3 (TO-236) surface mount package. This device is designed for general-purpose switching and amplification applications requiring a 30 V collector-emitter breakdown voltage rating with 100 mA maximum collector current and 250 mW power dissipation capability. The BC858B operates across a temperature range of -55°C to 150°C and features a 100 MHz transition frequency.

Equivalent and substitute parts are necessary when the primary part number becomes unavailable, when alternative packaging formats are required, or when sourcing from multiple manufacturers is required for supply chain continuity. Substitute parts must maintain electrical compatibility across critical parameters including voltage ratings, current ratings, power dissipation, and frequency response while maintaining the same physical package footprint.

Key Parameters

Parameter	BC858B (Infineon)	Unit
Transistor Type	PNP	—
Collector Current (Max)	100	mA
Collector-Emitter Breakdown Voltage (Max)	30	V
Power Dissipation (Max)	250	mW
Transition Frequency	100	MHz
Operating Temperature Range	-55 to 150	°C
Package Type	SOT-23-3 (TO-236)	—
Mounting Type	Surface Mount	—
Vce Saturation @ 5mA, 100mA	650	mV
DC Current Gain (hFE) @ 2mA, 5V	220 (Min)	—

Substitute Part Grouping Explanation

Substitution eligibility for the BC858B is determined by strict adherence to the following electrical and mechanical parameters:

Critical Parameters for Substitution:

Transistor polarity (PNP)
Collector-emitter breakdown voltage (30 V minimum)
Maximum collector current (100 mA minimum)
Maximum power dissipation (250 mW minimum)
Transition frequency (100 MHz minimum)
Operating temperature range (-55°C to 150°C minimum)
Physical package (SOT-23-3 / TO-236 surface mount)

All substitute parts listed maintain these critical electrical specifications and physical package compatibility. Variations in DC current gain (hFE), power dissipation ceiling, and transition frequency above the minimum thresholds do not preclude substitution, as these represent enhanced or equivalent performance characteristics. Packaging format variations (Cut Tape vs. Tape & Reel) represent different supply configurations of the same electrical component and do not affect functional compatibility.

Parameter Comparison

Parameter	BC858B (Infineon)	BC858ALT1G (onsemi)	BC858B_R1_00001 (Panjit)	BC858CLT1G (onsemi)	NSVBC858CLT1G (onsemi)	Unit
Transistor Type	PNP	PNP	PNP	PNP	PNP	—
Collector Current (Max)	100	100	100	100	100	mA
Collector-Emitter Breakdown Voltage (Max)	30	30	30	30	30	V
Power Dissipation (Max)	250	300	330	300	300	mW
Transition Frequency	100	100	200	100	100	MHz
Operating Temperature Range	-55 to 150	-55 to 150	-50 to 150	-55 to 150	-55 to 150	°C
Package Type	SOT-23-3 (TO-236)	SOT-23-3 (TO-236)	SOT-23-3 (TO-236)	SOT-23-3 (TO-236)	SOT-23-3 (TO-236)	—
Vce Saturation @ 5mA, 100mA	650	650	650	650	650	mV
DC Current Gain (hFE) @ 2mA, 5V	220 (Min)	125 (Min)	220 (Min)	420 (Min)	420 (Min)	—
RoHS Status	Not applicable	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	—

Engineering Selection Recommendations

BC858ALT1G (onsemi) — Direct electrical equivalent with identical voltage, current, and frequency specifications. Offers enhanced power dissipation (300 mW vs. 250 mW) and ROHS3 compliance. Available in Cut Tape and Digi-Reel packaging formats. Suitable for applications requiring RoHS certification.

BC858B_R1_00001 (Panjit International Inc.) — Meets all critical electrical parameters with enhanced transition frequency (200 MHz vs. 100 MHz) and power dissipation (330 mW vs. 250 mW). Operates across -50°C to 150°C temperature range (minimum -50°C vs. -55°C). Supplied in Tape & Reel format. ROHS3 compliant. Appropriate for high-frequency applications within the specified temperature range.

BC858CLT1G (onsemi) — Electrical equivalent with identical voltage, current, and frequency specifications. Features enhanced DC current gain (420 Min vs. 220 Min) and power dissipation (300 mW vs. 250 mW). Available in Cut Tape and Digi-Reel packaging. ROHS3 compliant. Suitable for applications where higher current gain provides design margin.

NSVBC858CLT1G (onsemi) — Electrical equivalent with identical voltage, current, and frequency specifications. Features enhanced DC current gain (420 Min vs. 220 Min) and power dissipation (300 mW vs. 250 mW). Supplied in Tape & Reel format. ROHS3 compliant. Appropriate for high-volume production requiring tape and reel packaging.

All substitute parts maintain active product status and REACH compliance. Selection between alternatives depends on packaging format requirements (Cut Tape vs. Tape & Reel), RoHS certification necessity, and performance margin requirements.

Frequently Asked Questions (FAQ)

Q: Can BC858ALT1G replace BC858B in all applications?

A: Yes. BC858ALT1G maintains identical electrical specifications for collector current (100 mA), collector-emitter breakdown voltage (30 V), transition frequency (100 MHz), and operating temperature range (-55°C to 150°C). Enhanced power dissipation (300 mW vs. 250 mW) provides additional thermal margin. Both devices use the SOT-23-3 package with identical pinout and footprint.

Q: What is the difference between BC858B_R1_00001 and BC858B?

A: BC858B_R1_00001 maintains all critical electrical parameters but offers enhanced transition frequency (200 MHz vs. 100 MHz) and power dissipation (330 mW vs. 250 mW). The minimum operating temperature is -50°C versus -55°C for the BC858B. Both use SOT-23-3 packaging. The higher frequency rating makes BC858B_R1_00001 suitable for applications requiring faster switching performance.

Q: Are packaging format differences (Cut Tape vs. Tape & Reel) significant for substitution?

A: Packaging format differences do not affect electrical compatibility or functional performance. Cut Tape (CT) and Digi-Reel packaging are supply configurations suitable for manual or semi-automated assembly. Tape & Reel (TR) format is optimized for high-volume automated pick-and-place assembly. Selection depends on manufacturing process requirements, not component functionality.

Q: Why do some substitute parts have higher DC current gain (hFE) values?

A: DC current gain variation within the same device family reflects manufacturing process differences between suppliers. BC858CLT1G and NSVBC858CLT1G specify minimum hFE of 420 at 2mA, 5V, compared to 220 for BC858B. Higher current gain does not preclude substitution; it represents enhanced performance that maintains backward compatibility in circuit designs.

Q: Is the BC858B suitable for applications requiring RoHS compliance?

A: The BC858B is marked as "Not applicable" for RoHS status. For applications requiring RoHS3 compliance, substitute parts BC858ALT1G, BC858B_R1_00001, BC858CLT1G, and NSVBC858CLT1G are all ROHS3 compliant and maintain electrical equivalence.

Q: Can BC858CLT1G and NSVBC858CLT1G be used interchangeably?

A: Yes. Both parts are manufactured by onsemi with identical electrical specifications, package type (SOT-23-3), and RoHS compliance. The primary difference is packaging format: BC858CLT1G is supplied in Cut Tape and Digi-Reel, while NSVBC858CLT1G is supplied in Tape & Reel. Selection depends on assembly equipment compatibility.

Q: What is the minimum collector-emitter breakdown voltage for safe substitution?

A: All substitute parts maintain the 30 V collector-emitter breakdown voltage specification, matching the BC858B requirement. This parameter is critical for circuit protection and must not be reduced in any substitution scenario.

Q: Are there temperature range limitations when substituting BC858B_R1_00001?

A: BC858B_R1_00001 operates from -50°C to 150°C, compared to BC858B at -55°C to 150°C. The minimum temperature is 5°C higher. For applications requiring operation below -50°C, BC858B, BC858ALT1G, BC858CLT1G, or NSVBC858CLT1G are required.

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