MSD1328-ST1G Equivalent & Substitute Parts

Part Overview

The MSD1328-ST1G is an NPN bipolar junction transistor manufactured by onsemi, rated for 20 V collector-emitter breakdown voltage and 500 mA maximum collector current in a surface mount SC-59 package. This device is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement continuity. The 200 mW power rating and SC-59 packaging make this transistor suitable for general-purpose switching and amplification applications in compact form factors.

Key Parameters

Parameter	Value	Unit
Transistor Type	NPN	—
Collector Current (Max)	500	mA
Collector-Emitter Breakdown Voltage (Max)	20	V
Power Dissipation (Max)	200	mW
Vce Saturation (Max)	400	mV @ 20mA, 500mA
DC Current Gain (hFE Min)	300	@ 500mA, 2V
Collector Cutoff Current (Max)	100	nA
Operating Temperature (Max)	150	°C
Package Type	SC-59 / SOT-23-3	—
Mounting Type	Surface Mount	—

Substitute Part Grouping Explanation

Substitution of the MSD1328-ST1G is determined by strict alignment of electrical and mechanical parameters. The primary substitution criteria are:

Mandatory Matching Parameters:

Transistor Type: NPN
Collector Current (Max): 500 mA minimum
Collector-Emitter Breakdown Voltage (Max): 20 V minimum
Power Dissipation (Max): 200 mW minimum
Package Type: SC-59 / SOT-23-3 surface mount
Mounting Type: Surface Mount

Substitution Categories:

Direct Equivalent: Parts meeting all mandatory parameters with identical or superior electrical ratings and active product status.

Compatible Substitute: Parts exceeding one or more electrical parameters (higher voltage rating, higher current capacity, or higher power dissipation) while maintaining the same package footprint and mounting type. These parts are electrically backward-compatible but may have different thermal or frequency characteristics.

The substitute parts listed below are grouped by their relationship to the MSD1328-ST1G based on these criteria.

Parameter Comparison

Parameter	MSD1328-ST1G	2SD2114KT146V	BC818K40E6327HTSA1	FMMT618TA	MMS8050-H-TP	MMS8050-L-TP	PBSS4120T,215
Manufacturer	onsemi	Rohm Semiconductor	Infineon Technologies	Diodes Incorporated	Micro Commercial Co	Micro Commercial Co	Nexperia USA Inc.
Product Status	Obsolete	Active	Obsolete	Active	Active	Active	Active
Transistor Type	NPN	NPN	NPN	NPN	NPN	NPN	NPN
Ic (Max) [mA]	500	500	500	2500	500	500	1000
Vce Breakdown (Max) [V]	20	20	25	20	25	25	20
Power (Max) [mW]	200	200	500	625	300	300	480
Vce Saturation (Max) [mV]	400 @ 20mA, 500mA	400 @ 20mA, 500mA	700 @ 50mA, 500mA	200 @ 50mA, 2.5A	600 @ 50mA, 500mA	600 @ 50mA, 500mA	250 @ 50mA, 1A
hFE (Min)	300 @ 500mA, 2V	820 @ 10mA, 3V	250 @ 100mA, 1V	200 @ 2A, 2V	120 @ 50mA, 1V	120 @ 50mA, 1V	300 @ 500mA, 2V
Frequency - Transition [MHz]	—	350	170	140	150	150	100
Operating Temperature (Max) [°C]	150	150	150	150	150	150	150
Package / Case	SC-59 / SOT-23-3	SC-59 / SOT-23-3	SC-59 / SOT-23-3	SC-59 / SOT-23-3	SC-59 / SOT-23-3	SC-59 / SOT-23-3	SC-59 / SOT-23-3
RoHS Status	—	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Moisture Sensitivity Level	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)
REACH Status	REACH Unaffected	REACH Unaffected	REACH Unaffected	REACH Unaffected	REACH Unaffected	REACH Unaffected	REACH Unaffected

Engineering Selection Recommendations

Primary Recommendation: 2SD2114KT146V (Rohm Semiconductor)

The 2SD2114KT146V is the closest direct equivalent to the MSD1328-ST1G. It matches the critical electrical parameters: 500 mA collector current, 20 V breakdown voltage, and 200 mW power dissipation. The part is in active production status, ensuring long-term availability. It carries ROHS3 compliance and maintains identical package specifications (SC-59 / SOT-23-3). The higher DC current gain (820 @ 10mA, 3V) and transition frequency (350 MHz) provide superior performance margins for switching applications.

Secondary Recommendation: PBSS4120T,215 (Nexperia USA Inc.)

The PBSS4120T,215 is suitable for applications requiring higher current capacity. It provides 1 A maximum collector current and 480 mW power dissipation while maintaining the 20 V breakdown voltage specification. This part carries AEC-Q100 automotive qualification and ROHS3 compliance. The TO-236AB package is mechanically compatible with SC-59 footprints. This selection is appropriate when design margins for current handling are required.

Alternative Recommendation: FMMT618TA (Diodes Incorporated)

The FMMT618TA offers significantly higher current capacity (2.5 A) and power dissipation (625 mW) in the same SC-59 / SOT-23-3 package. This part is in active production and ROHS3 compliant. Selection of this part is appropriate for applications where higher current capability provides design flexibility, though the higher power rating may introduce unnecessary thermal considerations for 500 mA applications.

Compatible Substitutes: MMS8050-H-TP and MMS8050-L-TP (Micro Commercial Co)

Both MMS8050 variants provide 500 mA collector current but with elevated breakdown voltage (25 V) and higher power dissipation (300 mW). These parts are in active production with ROHS3 compliance. The MMS8050-H-TP is supplied in Cut Tape & Digi-Reel packaging, while MMS8050-L-TP is supplied in Tape & Reel format. These parts are electrically backward-compatible but introduce higher voltage and power margins than required for 20 V applications.

Not Recommended: BC818K40E6327HTSA1 (Infineon Technologies)

The BC818K40E6327HTSA1 is classified as obsolete and carries a higher Vce saturation specification (700 mV @ 50mA, 500mA) compared to the MSD1328-ST1G (400 mV). While the 25 V breakdown voltage and 500 mA current rating are compatible, the obsolete status and inferior saturation characteristics make this part unsuitable for new designs.

Frequently Asked Questions (FAQ)

Q: Can the 2SD2114KT146V directly replace the MSD1328-ST1G without circuit modifications?

A: Yes. The 2SD2114KT146V meets or exceeds all critical electrical parameters of the MSD1328-ST1G: collector current (500 mA), breakdown voltage (20 V), power dissipation (200 mW), and package type (SC-59 / SOT-23-3). The higher DC current gain and transition frequency provide improved performance margins. No circuit modifications are required.

Q: What is the difference between MMS8050-H-TP and MMS8050-L-TP?

A: Both parts are electrically identical with 500 mA collector current, 25 V breakdown voltage, and 300 mW power dissipation. The primary difference is packaging format: MMS8050-H-TP is supplied in Cut Tape & Digi-Reel format, while MMS8050-L-TP is supplied in Tape & Reel format. Selection depends on procurement and assembly requirements.

Q: Why is the PBSS4120T,215 rated for 1 A when the MSD1328-ST1G is rated for 500 mA?

A: The PBSS4120T,215 is a higher-current variant in the same package family. The 1 A rating reflects the device's internal design and thermal characteristics. For applications requiring only 500 mA, the PBSS4120T,215 operates well within its ratings and provides design margin. The 20 V breakdown voltage matches the MSD1328-ST1G specification.

Q: Are all substitute parts RoHS compliant?

A: All active substitute parts listed (2SD2114KT146V, FMMT618TA, MMS8050-H-TP, MMS8050-L-TP, and PBSS4120T,215) carry ROHS3 compliance certification. The obsolete BC818K40E6327HTSA1 also carries ROHS3 compliance but is not recommended due to product status.

Q: What does "REACH Unaffected" mean for these transistors?

A: REACH Unaffected status indicates that the substance composition of these transistors does not fall under the REACH (Registration, Evaluation, Authorization and Restriction of Chemicals) regulatory framework. All listed parts carry this designation, confirming compliance with European chemical regulations.

Q: Can I use FMMT618TA in a circuit designed for 500 mA operation?

A: Yes. The FMMT618TA is rated for 2.5 A maximum collector current, making it suitable for 500 mA applications. The device operates well within its electrical ratings. The higher current capacity provides design margin but does not affect circuit functionality at lower current levels. The 20 V breakdown voltage matches the MSD1328-ST1G specification.

Q: What is the significance of the SC-59 package designation?

A: SC-59 is the industry standard designation for a three-lead surface mount package, also known as SOT-23-3 or TO-236-3. All substitute parts listed use this identical package footprint, ensuring mechanical and electrical compatibility with existing PCB layouts designed for the MSD1328-ST1G.

Q: Why is the MSD1328-ST1G classified as obsolete?

A: Obsolete status indicates that the manufacturer (onsemi) has discontinued production of this part. Active substitute parts ensure design continuity and long-term procurement availability. The 2SD2114KT146V is the recommended replacement for new designs and ongoing production.

Q: What is the Moisture Sensitivity Level (MSL) rating, and why is it important?

A: MSL 1 (Unlimited) indicates that these transistors have no moisture sensitivity restrictions. The devices can be stored and handled without special moisture control measures, simplifying procurement, storage, and assembly processes compared to higher MSL-rated components.

Request Quote (Ships tomorrow)

Part Number

Quantity

Company

Contact Name

E-mail

Message