BC859AMTF Equivalent & Substitute Parts

Part Overview

The BC859AMTF is a PNP bipolar junction transistor manufactured by onsemi, designed for general-purpose switching and amplification applications in surface mount configurations. This device operates at a maximum collector current of 100 mA with a collector-emitter breakdown voltage of 30 V and a maximum power dissipation of 310 mW. The BC859AMTF is classified as obsolete, necessitating identification of active equivalent and substitute components for new designs and ongoing production requirements. Substitute parts must maintain electrical compatibility within the specified parameter ranges while offering active product status and current manufacturing availability.

Key Parameters

Parameter	BC859AMTF 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
DC Current Gain (hFE) (Min) @ Ic, Vce	110 @ 2 mA, 5 V	—
Power - Max	310	mW
Frequency - Transition	150	MHz
Package / Case	SOT-23-3 (TO-236-3, SC-59)	—
Mounting Type	Surface Mount	—
Operating Temperature (Max)	150	°C
Moisture Sensitivity Level (MSL)	1 (Unlimited)	—

Substitute Part Grouping Explanation

Substitute parts for the BC859AMTF are selected based on strict electrical and mechanical compatibility criteria. The primary substitution parameters are:

Critical Matching Parameters:

Transistor Type: PNP (mandatory)
Package / Case: SOT-23-3 (TO-236-3, SC-59) (mandatory)
Current - Collector (Ic) (Max): 100 mA (mandatory)
Voltage - Collector Emitter Breakdown (Max): ≥ 30 V (minimum requirement)
Mounting Type: Surface Mount (mandatory)

Secondary Compatibility Parameters:

Vce Saturation: ≤ 650 mV @ specified test conditions
Current - Collector Cutoff (Max): ≤ 15 nA
DC Current Gain (hFE): ≥ 110 @ 2 mA, 5 V
Power - Max: ≥ 310 mW
Frequency - Transition: ≥ 150 MHz (where specified)

Substitute parts are grouped into two categories:

Category A - Direct Electrical Equivalents (BC858 Series): Parts meeting or exceeding all critical parameters with identical or superior electrical performance. These include BC858ALT1G, BC858BLT1G, BC858BLT3G, BC858CLT1G, BC858CLT3G, NSVBC858BLT1G, and NSVBC858CLT1G. These parts operate at 100 MHz transition frequency (lower than the original 150 MHz) but maintain all other critical specifications and offer active product status with RoHS3 compliance.

Category B - Functional Equivalents (BCW30 Series and 2SB1695KT146): Parts with voltage ratings equal to or exceeding 30 V, identical collector current ratings, and compatible packaging. BCW30LT1G and SBCW30LT1G operate at 32 V breakdown voltage with different saturation characteristics. The 2SB1695KT146 exceeds current rating specifications (1.5 A vs. 100 mA) and operates at 280 MHz, suitable for applications requiring higher current capacity.

Parameter Comparison

Part Number	Manufacturer	Product Status	Ic (Max) mA	Vce Breakdown (Max) V	Vce Sat (Max) mV	hFE (Min) @ 2mA, 5V	Power (Max) mW	Freq - Transition MHz	Package	RoHS Status
BC859AMTF	onsemi	Obsolete	100	30	650	110	310	150	SOT-23-3	—
BC858ALT1G	onsemi	Active	100	30	650	125	300	100	SOT-23-3	ROHS3
BC858BLT1G	onsemi	Active	100	30	650	220	300	100	SOT-23-3	ROHS3
BC858BLT3G	onsemi	Active	100	30	650	220	300	100	SOT-23-3	ROHS3
BC858CLT1G	onsemi	Active	100	30	650	420	300	100	SOT-23-3	ROHS3
BC858CLT3G	onsemi	Active	100	100	650	420	300	100	SOT-23-3	ROHS3
BCW30LT1G	onsemi	Active	100	32	300	215	300	—	SOT-23-3	ROHS3
NSVBC858BLT1G	onsemi	Active	100	30	650	220	300	100	SOT-23-3	ROHS3
NSVBC858CLT1G	onsemi	Active	100	30	650	420	300	100	SOT-23-3	ROHS3
SBCW30LT1G	onsemi	Active	100	32	300	215	300	—	SOT-23-3	ROHS3
2SB1695KT146	Rohm Semiconductor	Active	1500	30	370	270	200	280	SOT-23-3	ROHS3

Engineering Selection Recommendations

For Direct Replacement in Active Production:

The BC858 series (BC858ALT1G, BC858BLT1G, BC858BLT3G, BC858CLT1G, BC858CLT3G) and NSVBC858 series (NSVBC858BLT1G, NSVBC858CLT1G) are recommended as primary substitutes. All maintain the 30 V collector-emitter breakdown voltage, 100 mA maximum collector current, and SOT-23-3 package specification. These parts are manufactured by onsemi with active product status and ROHS3 compliance. The transition frequency is reduced to 100 MHz compared to the original 150 MHz; applications requiring frequencies above 100 MHz require circuit-level evaluation. DC current gain (hFE) values range from 125 to 420 at the specified test conditions, providing design flexibility for gain-dependent circuits.

For Applications Requiring Extended Voltage Margin:

BCW30LT1G and SBCW30LT1G offer 32 V collector-emitter breakdown voltage, providing 2 V additional margin over the original specification. These parts feature lower saturation voltage (300 mV vs. 650 mV) and are suitable for applications where reduced saturation losses are beneficial. SBCW30LT1G includes automotive-grade qualification (AEC-Q101) for applications requiring automotive reliability standards.

For High-Current Applications:

The 2SB1695KT146 from Rohm Semiconductor accommodates collector currents up to 1.5 A while maintaining 30 V breakdown voltage and SOT-23-3 packaging. This part operates at 280 MHz transition frequency and features lower saturation voltage (370 mV). Selection of this part is appropriate only when circuit design requires current capacity exceeding 100 mA.

Compliance and Availability:

All recommended substitute parts carry ROHS3 compliance and REACH unaffected status. Packaging options include Cut Tape (CT) & Digi-Reel® and Tape & Reel (TR) configurations to accommodate different procurement and assembly workflows.

Frequently Asked Questions (FAQ)

Q: Can BC858ALT1G directly replace BC859AMTF in all applications?

A: BC858ALT1G maintains electrical compatibility for applications operating at transition frequencies up to 100 MHz. The original BC859AMTF specifies 150 MHz transition frequency. Applications requiring operation above 100 MHz require circuit-level frequency response analysis. All other electrical parameters (voltage, current, saturation characteristics) are compatible.

Q: What is the difference between BC858BLT1G and BC858CLT1G?

A: Both parts are electrically identical except for DC current gain (hFE). BC858BLT1G specifies minimum hFE of 220 at 2 mA, 5 V, while BC858CLT1G specifies minimum hFE of 420. Selection depends on circuit gain requirements. Higher hFE in BC858CLT1G reduces base drive requirements in switching applications.

Q: Why does BCW30LT1G have lower saturation voltage than BC858 series parts?

A: BCW30LT1G is optimized for switching applications with saturation voltage of 300 mV at 500 µA base current and 10 mA collector current, compared to 650 mV for BC858 series at 5 mA base current and 100 mA collector current. These represent different test conditions reflecting different application profiles. BCW30LT1G is suitable for low-loss switching circuits.

Q: Is SBCW30LT1G suitable for automotive applications?

A: SBCW30LT1G carries AEC-Q101 automotive qualification and is designed for automotive-grade reliability. This part is appropriate for automotive applications requiring extended temperature range (-55°C to 150°C) and automotive supply chain compliance.

Q: Can 2SB1695KT146 be used as a direct substitute for BC859AMTF?

A: 2SB1695KT146 is electrically compatible for voltage and package specifications but exceeds current rating (1.5 A vs. 100 mA). This part is suitable only when circuit design requires higher current capacity. Using this part in circuits designed for 100 mA operation does not provide functional benefit and may introduce unnecessary cost.

Q: What packaging options are available for BC858 series substitutes?

A: BC858 series parts are available in Cut Tape (CT) & Digi-Reel® packaging (BC858ALT1G, BC858BLT1G, BC858CLT1G) and Tape & Reel (TR) packaging (BC858BLT3G, BC858CLT3G). Selection depends on assembly equipment compatibility and procurement workflow requirements.

Q: Are all substitute parts RoHS3 compliant?

A: All recommended substitute parts carry ROHS3 compliance certification. The original BC859AMTF does not specify RoHS status. RoHS3 compliance is a design advantage for new production and ensures compliance with current environmental regulations.

Q: What is the moisture sensitivity level (MSL) for substitute parts?

A: All substitute parts carry MSL 1 (Unlimited), indicating no moisture sensitivity restrictions. Storage and handling requirements are identical to the original BC859AMTF.

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