BC857A Equivalent & Substitute Parts Reference

Part Overview

The BC857A, manufactured by Taiwan Semiconductor Corporation, is a PNP bipolar junction transistor (BJT) designed for general-purpose switching and amplification applications. This device is supplied in a SOT-23 surface-mount package and supports a maximum collector current of 100 mA with a collector-emitter breakdown voltage of 45 V. The BC857A is currently listed as an active product with substantial inventory available. In certain scenarios, sourcing alternative models is necessary due to supply constraints, production discontinuities, packaging preferences, or qualification requirements. Identifying compatible equivalents and substitutes ensures design continuity and mitigates the risk of supply interruptions.

Key Parameters

Parameter	BC857A (Main Part)
Transistor Type	PNP
Current - Collector (Ic) (Max)	100 mA
Voltage - Collector Emitter Breakdown (Max)	45 V
Vce Saturation (Max) @ Ib, Ic	650mV @ 5mA, 100mA
Current - Collector Cutoff (Max) (ICBO)	100nA
DC Current Gain (hFE) (Min) @ Ic, Vce	125 @ 2mA, 5V
Power - Max	200 mW
Frequency - Transition	100MHz
Operating Temperature	-55°C ~ 150°C (TJ)
Mounting Type	Surface Mount
Package / Case	TO-236-3, SC-59, SOT-23-3
Supplier Device Package	SOT-23
RoHS Status	ROHS3 Compliant
REACH Status	REACH Unaffected

Substitute Part Grouping Explanation

Substitute criteria are strictly defined by parametric equivalence in transistor type (PNP), maximum collector current (100 mA), breakdown voltage (45 V), Vce saturation characteristics, cutoff current, minimum DC current gain, maximum power dissipation, transition frequency, operating temperature, surface-mount packages, RoHS and REACH status. Parts listed as substitutes meet or exceed these specifications, either identically or within defined allowable ranges, and are supplied in equivalent packages suitable for direct PCB replacement.

Parameter Comparison

Manufacturer Part Number	Manufacturer	Transistor Type	Ic (Max)	Vce Breakdown (Max)	Vce Saturation (Max)	ICBO (Max)	hFE (Min)	Power (Max)	Frequency (ft)	Operating Temp	Mounting Type	Package / Case	Supplier Device Package	RoHS Status	REACH Status
BC857A	Taiwan Semiconductor Corporation	PNP	100 mA	45 V	650mV @ 5mA, 100mA	100nA	125 @ 2mA, 5V	200 mW	100MHz	-55°C ~ 150°C (TJ)	Surface Mount	TO-236-3, SC-59, SOT-23-3	SOT-23	ROHS3 Compliant	REACH Unaffected
BC857A RFG	Taiwan Semiconductor Corporation	PNP	100 mA	45 V	650mV @ 5mA, 100mA	100nA	125 @ 2mA, 5V	200 mW	100MHz	-55°C ~ 150°C (TJ)	Surface Mount	TO-236-3, SC-59, SOT-23-3	SOT-23	ROHS3 Compliant	REACH Unaffected
BC857B-TP	Micro Commercial Co	PNP	100 mA	45 V	650mV @ 5mA, 100mA	15nA	220 @ 2mA, 5V	310 mW	200MHz	-55°C ~ 150°C (TJ)	Surface Mount	TO-236-3, SC-59, SOT-23-3	SOT-23	ROHS3 Compliant	REACH Unaffected
BC857BR TR PBFREE	Central Semiconductor Corp	PNP	100 mA	45 V	650mV @ 5mA, 100mA	15nA	220 @ 2mA, 5V	350 mW	100MHz	-65°C ~ 150°C (TJ)	Surface Mount	TO-236-3, SC-59, SOT-23-3	SOT-23	ROHS3 Compliant	REACH Unaffected
BCX71GE6327HTSA1	Infineon Technologies	PNP	100 mA	45 V	550mV @ 1.25mA, 50mA	20nA	120 @ 2mA, 5V	330 mW	250MHz	150°C (TJ)	Surface Mount	TO-236-3, SC-59, SOT-23-3	PG-SOT23	ROHS3 Compliant	REACH Unaffected
BCX71H,215	Nexperia USA Inc.	PNP	100 mA	45 V	550mV @ 1.25mA, 50mA	20nA	180 @ 2mA, 5V	250 mW	100MHz	150°C (TJ)	Surface Mount	TO-236-3, SC-59, SOT-23-3	TO-236AB	ROHS3 Compliant	REACH Unaffected

Engineering Selection Recommendations

Only select parts with an active product status for current designs. Ensure the substitute part maintains ROHS3 Compliant and REACH Unaffected status, as indicated. Always verify mounting type, package/case compatibility, and supplier device package before specifying in the BOM; all listed substitutes utilize surface mount SOT-23 footprint or equivalent. Where automotive or specific qualification is present (e.g., AEC-Q101), ensure alignment with application requirements.

Frequently Asked Questions (FAQ)

Q1: What are the critical parameters for BC857A substitution?
Acceptable substitutes must match transistor type (PNP), Ic (100 mA max), Vce breakdown (45 V max), package/case, mounting type, and compliance documentation.

Q2: Can different package designations (e.g., PG-SOT23, TO-236AB) be substituted directly for SOT-23?
All listed packages are compatible with SOT-23 footprint standards within the substitutions provided.

Q3: How does DC current gain (hFE) or frequency affect substitution choices?
Parameter ranges for hFE and transition frequency provided by substitutes are within or exceed main part specifications, maintaining compatibility.

Q4: Are there compliance differences among substitutes?
All substitutes listed are ROHS3 Compliant and REACH Unaffected. Automotive grade (AEC-Q101) is indicated where appropriate.

Q5: When should the exact manufacturer part number be selected over substitutes?
Select the exact part for validated designs or where manufacturer-specific documentation is required. Substitute parts are suitable if all application parameters and certifications align with the requirements listed above.

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