BSS64LT1 NPN Bipolar Junction Transistor Equivalent & Substitute Parts

Part Overview

The BSS64LT1 is an NPN bipolar junction transistor manufactured by onsemi, designed for surface mount applications in the SOT-23-3 package. This device operates at a maximum collector voltage of 80 V with a collector current rating of 100 mA and a maximum power dissipation of 225 mW. The BSS64LT1 is classified as obsolete, which necessitates identification of equivalent and substitute components for ongoing design requirements and production continuity. Active alternatives with identical or enhanced electrical characteristics are available from multiple manufacturers.

Key Parameters

Parameter	Value	Unit
Transistor Type	NPN	—
Collector Current (Max)	100	mA
Collector-Emitter Breakdown Voltage (Max)	80	V
Vce Saturation (Max)	200	mV @ 15mA, 50mA
Collector Cutoff Current (Max)	100	nA
DC Current Gain (hFE Min)	20	@ 10mA, 1V
Power Dissipation (Max)	225	mW
Transition Frequency	60	MHz
Operating Temperature Range	−55 to 150	°C
Package Type	SOT-23-3 (TO-236)	—
Mounting Type	Surface Mount	—

Substitute Part Grouping Explanation

Substitution of the BSS64LT1 is determined by strict equivalence or enhancement across the following critical parameters:

Mandatory Equivalence Criteria:

Transistor type: NPN
Package type: SOT-23-3 (TO-236) or compatible surface mount package
Collector-Emitter breakdown voltage: minimum 80 V
Collector current rating: minimum 100 mA
Operating temperature range: minimum −55 to 150 °C

Acceptable Enhancement Parameters:

Collector current rating may exceed 100 mA
Power dissipation may exceed 225 mW
Transition frequency may exceed 60 MHz
DC current gain may exceed 20 (minimum)
Collector-Emitter saturation voltage may be lower than 200 mV

Substitutes are grouped into two categories: direct equivalents (identical electrical specifications and active product status) and similar alternatives (enhanced performance characteristics with compatible package and voltage ratings).

Parameter Comparison

Part Number	Manufacturer	Ic (Max) mA	Vce(br) V	Vce Sat mV	hFE (Min)	Power mW	fT MHz	Package	Product Status	RoHS
BSS64LT1	onsemi	100	80	200	20	225	60	SOT-23-3	Obsolete	Non-compliant
BSS64LT1G	onsemi	100	80	200	20	225	60	SOT-23-3	Active	Compliant
BC846B RFG	Taiwan Semiconductor	100	65	500	200	200	100	SOT-23	Active	Compliant
BC846B-TP	Micro Commercial Co	100	65	500	200	225	100	SOT-23	Active	Compliant
BC846A,215	Nexperia USA Inc.	100	65	400	110	250	100	TO-236AB	Active	Compliant
BSS64,215	Nexperia USA Inc.	100	80	200	20	250	100	TO-236AB	Not For New Designs	Compliant
2SCR514RTL	Rohm Semiconductor	700	80	300	120	1000	320	TSMT3	Active	Compliant
FMMT620TA	Diodes Incorporated	1500	80	200	300	625	160	SOT-23-3	Active	Compliant

Engineering Selection Recommendations

Direct Equivalent (Recommended Primary Choice):

BSS64LT1G is the direct functional equivalent of BSS64LT1. This part maintains identical electrical specifications across all critical parameters: 100 mA collector current, 80 V breakdown voltage, 200 mV saturation voltage, and 60 MHz transition frequency. BSS64LT1G carries active product status and RoHS3 compliance, addressing the obsolescence of the original BSS64LT1. This part is available in Cut Tape and Digi-Reel packaging with 15,401 units in stock.

Compatible Alternatives (Voltage-Rated Equivalents):

BC846B RFG, BC846B-TP, and BC846A,215 are compatible alternatives with identical 100 mA collector current ratings and SOT-23 package compatibility. These parts operate at 65 V breakdown voltage, which is lower than the 80 V rating of BSS64LT1. Selection of these alternatives is appropriate only when circuit design specifications do not require the full 80 V rating. All three alternatives are active products with RoHS3 compliance.

Enhanced Performance Alternative (Higher Current Capability):

FMMT620TA provides enhanced performance with 1.5 A collector current capability, 80 V breakdown voltage matching the original specification, and 625 mW power dissipation. This part maintains the SOT-23-3 package format and is suitable for applications requiring higher current handling. FMMT620TA is active and RoHS3 compliant.

Higher Current Alternative (Different Package):

2SCR514RTL from Rohm Semiconductor offers 700 mA collector current with 80 V breakdown voltage in the TSMT3 package. This part is suitable for applications requiring significantly higher current capacity but requires PCB layout modification due to package change from SOT-23-3 to TSMT3.

Legacy Alternative (Not Recommended for New Designs):

BSS64,215 from Nexperia maintains identical electrical specifications to BSS64LT1 with enhanced 250 mW power rating and 100 MHz transition frequency. This part carries "Not For New Designs" status and should not be selected for new circuit development.

Frequently Asked Questions (FAQ)

Q: Can BSS64LT1G be used as a direct replacement for BSS64LT1?

A: Yes. BSS64LT1G is electrically identical to BSS64LT1 across all specified parameters: 100 mA collector current, 80 V breakdown voltage, 200 mV saturation voltage, 20 minimum hFE, and 60 MHz transition frequency. The primary difference is product status (active versus obsolete) and RoHS3 compliance. BSS64LT1G is the recommended replacement.

Q: Are BC846 series transistors suitable replacements for BSS64LT1?

A: BC846 series transistors (BC846A,215, BC846B RFG, BC846B-TP) are compatible alternatives with the same 100 mA collector current and SOT-23 package. However, these parts operate at 65 V breakdown voltage compared to the 80 V rating of BSS64LT1. Selection of BC846 alternatives is appropriate only when circuit design does not require the full 80 V rating. Verify circuit voltage specifications before substitution.

Q: What is the difference between BSS64LT1 and BSS64,215?

A: Both parts share identical electrical specifications: 100 mA collector current, 80 V breakdown voltage, and 200 mV saturation voltage. BSS64,215 offers enhanced power dissipation (250 mW versus 225 mW) and higher transition frequency (100 MHz versus 60 MHz). BSS64,215 carries "Not For New Designs" status and should not be selected for new development. BSS64LT1G is the preferred active alternative.

Q: Can FMMT620TA replace BSS64LT1 in all applications?

A: FMMT620TA is electrically compatible with BSS64LT1 for voltage and package considerations: both operate at 80 V breakdown voltage and use SOT-23-3 packaging. FMMT620TA provides enhanced current capability (1.5 A versus 100 mA) and power dissipation (625 mW versus 225 mW). This part is suitable for applications requiring higher current handling. Verify that circuit design does not depend on the lower current rating of the original BSS64LT1.

Q: What packaging options are available for BSS64LT1 substitutes?

A: Direct equivalent BSS64LT1G is available in Cut Tape and Digi-Reel packaging. BC846 series alternatives are available in Tape & Reel packaging. BSS64,215 is available in Tape & Reel. FMMT620TA is available in Cut Tape and Digi-Reel. 2SCR514RTL is available in Cut Tape and Digi-Reel. Verify packaging requirements for automated assembly processes before final part selection.

Q: Are all substitute parts RoHS3 compliant?

A: All recommended substitute parts (BSS64LT1G, BC846 series, FMMT620TA, 2SCR514RTL) carry RoHS3 compliance. The original BSS64LT1 is RoHS non-compliant. RoHS3 compliance is required for most current applications and regulatory environments.

Q: What is the minimum collector-emitter breakdown voltage required for BSS64LT1 substitution?

A: The minimum acceptable breakdown voltage for direct substitution is 80 V, matching the original BSS64LT1 specification. Parts with 65 V breakdown voltage (BC846 series) are compatible only when circuit design specifications do not require the full 80 V rating. Verify maximum circuit voltage before selecting lower-rated alternatives.

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