BC858CW-G Equivalent & Substitute Parts

Part Overview

The BC858CW-G is an active PNP bipolar junction transistor manufactured by Comchip Technology, designed for general-purpose switching and amplification applications in surface mount configurations. This device operates at maximum collector currents of 100 mA with a collector-emitter breakdown voltage of 30 V and transition frequency of 100 MHz. The part is packaged in SOT-323 (SC-70) surface mount form factor with a maximum power dissipation of 150 mW.

Equivalent and substitute parts are identified when alternative manufacturers offer devices with identical or compatible electrical and mechanical specifications, enabling procurement flexibility, supply chain continuity, and cost optimization while maintaining circuit performance and reliability.

Key Parameters

Parameter	Value	Unit
Transistor Type	PNP	—
Current - Collector (Ic) Max	100	mA
Voltage - Collector Emitter Breakdown (Max)	30	V
Vce Saturation (Max) @ Ib, Ic	650 mV @ 5 mA, 100 mA	—
Current - Collector Cutoff (Max)	15	nA
Power - Max	150	mW
Frequency - Transition	100	MHz
Package / Case	SC-70, SOT-323	—
Mounting Type	Surface Mount	—
Operating Temperature Range	-65 to 150	°C
RoHS Status	ROHS3 Compliant	—
Moisture Sensitivity Level	1 (Unlimited)	—

Substitute Part Grouping Explanation

Substitution eligibility for the BC858CW-G is determined by strict equivalence across the following critical parameters:

Electrical Specifications:

Transistor polarity: PNP
Maximum collector current: 100 mA
Collector-emitter breakdown voltage: 30 V
Maximum power dissipation: 150 mW
Transition frequency: 100 MHz
Saturation voltage characteristics: 650 mV @ 5 mA, 100 mA

Mechanical Specifications:

Package type: SOT-323 (SC-70) surface mount
Mounting method: Surface mount

Compliance & Environmental:

RoHS3 compliance
Moisture sensitivity level: 1 (Unlimited)

Substitute parts must satisfy all electrical parameters within the specified tolerances and maintain identical package and mounting characteristics. DC current gain (hFE) variations are permitted within the range specified by individual manufacturer datasheets, provided all other parameters remain equivalent.

Parameter Comparison

Parameter	BC858CW-G (Comchip)	BC858AWT1G (onsemi)	Compatibility
Transistor Type	PNP	PNP	Equivalent
Current - Collector (Ic) Max	100 mA	100 mA	Equivalent
Voltage - Collector Emitter Breakdown (Max)	30 V	30 V	Equivalent
Vce Saturation (Max) @ Ib, Ic	650 mV @ 5 mA, 100 mA	650 mV @ 5 mA, 100 mA	Equivalent
Current - Collector Cutoff (Max)	15 nA	15 nA	Equivalent
Power - Max	150 mW	150 mW	Equivalent
Frequency - Transition	100 MHz	100 MHz	Equivalent
Package / Case	SC-70, SOT-323	SC-70, SOT-323	Equivalent
Mounting Type	Surface Mount	Surface Mount	Equivalent
Operating Temperature Range	-65 to 150 °C	-55 to 150 °C	onsemi range narrower at lower limit
DC Current Gain (hFE) Min @ Ic, Vce	420 @ 2 mA, 5 V	125 @ 2 mA, 5 V	Different specifications
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	Equivalent
Moisture Sensitivity Level	1 (Unlimited)	1 (Unlimited)	Equivalent

Engineering Selection Recommendations

BC858AWT1G (onsemi) as Substitute:

The BC858AWT1G manufactured by onsemi is a direct electrical and mechanical substitute for the BC858CW-G. Both devices share identical ratings for collector current (100 mA), collector-emitter breakdown voltage (30 V), maximum power dissipation (150 mW), transition frequency (100 MHz), and saturation voltage characteristics (650 mV @ 5 mA, 100 mA). Both are packaged in SOT-323 surface mount configuration and comply with ROHS3 standards with MSL 1 rating.

The onsemi BC858AWT1G maintains active product status and is available in high inventory quantities (9933 pcs), ensuring supply chain reliability. Both parts are REACH unaffected and carry identical ECCN and HTSUS classifications.

Operating Temperature Consideration:

The BC858AWT1G operating temperature range (-55 to 150 °C) is narrower at the lower limit compared to the BC858CW-G (-65 to 150 °C). Applications requiring operation below -55 °C must retain the BC858CW-G.

DC Current Gain Variation:

The BC858AWT1G specifies a minimum DC current gain (hFE) of 125 @ 2 mA, 5 V, while the BC858CW-G specifies 420 @ 2 mA, 5 V. Circuits with gain-dependent biasing or requiring minimum hFE of 420 must verify compatibility with the lower onsemi specification before substitution.

Frequently Asked Questions (FAQ)

Q: Can BC858AWT1G replace BC858CW-G in all applications?

A: BC858AWT1G is electrically and mechanically equivalent for applications operating within the temperature range of -55 to 150 °C. Applications requiring operation below -55 °C or circuits dependent on minimum hFE of 420 require design verification before substitution.

Q: Are the SOT-323 and SC-70 packages identical?

A: Yes. SOT-323 and SC-70 refer to the same three-lead surface mount package with identical pin configuration, footprint, and mechanical dimensions. Both the BC858CW-G and BC858AWT1G use this package interchangeably.

Q: What is the significance of the different hFE specifications?

A: DC current gain (hFE) affects transistor biasing and switching characteristics. The BC858CW-G guarantees minimum hFE of 420, while BC858AWT1G guarantees 125. In circuits where base current is calculated based on required collector current and assumed gain, the lower onsemi specification may result in insufficient base drive. Circuit designers must verify bias resistor values and switching performance with the lower hFE value.

Q: Are both parts RoHS compliant?

A: Yes. Both BC858CW-G and BC858AWT1G are ROHS3 compliant with MSL 1 (Unlimited) moisture sensitivity rating, suitable for standard PCB assembly and storage conditions.

Q: What is the base product number relationship?

A: Both BC858CW-G and BC858AWT1G share the base product number BC858, indicating they are variants of the same generic PNP transistor design from different manufacturers with equivalent electrical specifications.

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