MSD601-ST1 Equivalent & Substitute Parts

Part Overview

The MSD601-ST1 is an NPN bipolar junction transistor manufactured by onsemi, rated for 50 V collector-emitter breakdown voltage and 100 mA maximum collector current in a surface mount SC-59 package. This device is classified as obsolete, indicating discontinuation from the manufacturer. Identification of equivalent and substitute parts is necessary to maintain design continuity and ensure component availability for production and repair applications.

Key Parameters

Parameter	Value
Transistor Type	NPN
Voltage - Collector Emitter Breakdown (Max)	50 V
Current - Collector (Ic) (Max)	100 mA
Power - Max	200 mW
Vce Saturation (Max) @ Ib, Ic	500mV @ 10mA, 100mA
DC Current Gain (hFE) (Min) @ Ic, Vce	290 @ 2mA, 10V
Current - Collector Cutoff (Max)	100nA
Package / Case	TO-236-3, SC-59, SOT-23-3
Mounting Type	Surface Mount
Operating Temperature	150°C (TJ)
RoHS Status	RoHS non-compliant

Substitute Part Grouping Explanation

Substitution of the MSD601-ST1 is determined by the following critical electrical and mechanical parameters:

Electrical Compatibility Criteria:

Transistor type must be NPN
Collector-emitter breakdown voltage must be greater than or equal to 50 V
Maximum collector current must be greater than or equal to 100 mA
Maximum power dissipation must be greater than or equal to 200 mW
Vce saturation characteristics must support the application requirements
DC current gain must be sufficient for circuit biasing

Mechanical Compatibility Criteria:

Package must be surface mount in TO-236-3, SC-59, or SOT-23-3 form factor
Mounting type must be surface mount
Operating temperature range must support 150°C maximum junction temperature

Compliance Considerations:

RoHS compliance status affects suitability for regulated applications
Product status (active vs. obsolete) determines long-term availability

Substitute parts are grouped into two categories: direct substitutes meeting or exceeding all electrical parameters with equivalent packaging, and similar substitutes with comparable electrical performance but potentially different package variants or enhanced specifications.

Parameter Comparison

Part Number	Manufacturer	Vce(BR)max (V)	Ic(Max) (mA)	Power (mW)	Vce Sat @ 10mA, 100mA (mV)	hFE(Min) @ 2mA, 10V	Package	Product Status	RoHS
MSD601-ST1	onsemi	50	100	200	500	290	SC-59	Obsolete	Non-compliant
2SC1623-L6-TP	Micro Commercial Co	50	100	200	300	—	SOT-23	Active	ROHS3 Compliant
BC847A RFG	Taiwan Semiconductor Corporation	45	100	200	500	110	SOT-23	Active	ROHS3 Compliant
2PD601ART,215	Nexperia USA Inc.	50	100	250	250	210	TO-236AB	Active	ROHS3 Compliant
2PD601ART,235	Nexperia USA Inc.	50	100	250	250	210	TO-236AB	Active	ROHS3 Compliant
2PD601ASL,215	Nexperia USA Inc.	50	100	250	250	290	TO-236AB	Active	ROHS3 Compliant
BC847B-7-F	Diodes Incorporated	45	100	300	600	200	SOT-23-3	Active	ROHS3 Compliant
BC847B-TP	Micro Commercial Co	45	100	225	500	200	SOT-23	Active	ROHS3 Compliant
BC847BE6327HTSA1	Infineon Technologies	45	100	330	600	200	PG-SOT23	Last Time Buy	ROHS3 Compliant
BC847C,215	Nexperia USA Inc.	45	100	250	400	420	TO-236AB	Active	ROHS3 Compliant
BC847C-TP	Micro Commercial Co	45	100	225	500	420	SOT-23	Active	ROHS3 Compliant

Engineering Selection Recommendations

Direct Substitutes (Electrical Equivalence):

The 2SC1623-L6-TP from Micro Commercial Co and the 2PD601 series from Nexperia USA Inc. (2PD601ART,215; 2PD601ART,235; 2PD601ASL,215) provide direct electrical substitution for the MSD601-ST1. These parts maintain the 50 V collector-emitter breakdown voltage and 100 mA maximum collector current specifications. The 2PD601 variants offer enhanced power dissipation (250 mW vs. 200 mW) and improved Vce saturation characteristics. The 2PD601ASL,215 variant matches the original hFE specification of 290 @ 2mA, 10V. All direct substitutes are ROHS3 compliant and carry active product status, ensuring long-term availability.

Similar Substitutes (Reduced Voltage Rating):

The BC847 series variants (BC847A RFG, BC847B-7-F, BC847B-TP, BC847BE6327HTSA1, BC847C,215, BC847C-TP) operate at 45 V collector-emitter breakdown voltage, which is 5 V lower than the original specification. These parts are suitable for applications where the 50 V rating is not critical to circuit operation. The BC847 series offers active product status and ROHS3 compliance. The BC847C variants provide higher DC current gain (420 @ 2mA, 5V) compared to the original part, which may require circuit biasing adjustments.

Compliance Status:

The MSD601-ST1 is RoHS non-compliant and obsolete. All recommended substitute parts are ROHS3 compliant and carry active or last-time-buy product status. Selection of substitute parts should prioritize active-status components for new designs and production applications.

Frequently Asked Questions (FAQ)

Q: Can the 2SC1623-L6-TP directly replace the MSD601-ST1 without circuit modification?

A: The 2SC1623-L6-TP maintains electrical equivalence in collector-emitter breakdown voltage (50 V), maximum collector current (100 mA), and power dissipation (200 mW). The primary difference is improved Vce saturation (300 mV vs. 500 mV), which reduces power loss. No circuit modification is required for direct substitution.

Q: Why do the BC847 series parts have a lower voltage rating (45 V vs. 50 V)?

A: The BC847 series is designed for general-purpose switching applications with a 45 V collector-emitter breakdown voltage. This 5 V reduction does not affect functionality in circuits designed for the MSD601-ST1 unless the application specifically requires the full 50 V margin. Verify circuit operating conditions before substitution.

Q: What is the difference between the 2PD601ART,215 and 2PD601ASL,215 variants?

A: Both parts share identical electrical specifications (50 V, 100 mA, 250 mW) and package type (TO-236AB). The primary difference is the DC current gain specification: 2PD601ART,215 specifies 210 @ 2mA, 10V, while 2PD601ASL,215 specifies 290 @ 2mA, 10V. The 2PD601ASL,215 matches the original MSD601-ST1 hFE specification and is preferred for applications with specific biasing requirements.

Q: Are all substitute parts available in the same package as the original MSD601-ST1?

A: The MSD601-ST1 uses the SC-59 package designation. Substitute parts are available in equivalent surface mount packages: SOT-23, SOT-23-3, TO-236AB, and PG-SOT23. These packages are mechanically and electrically compatible with SC-59 footprints on standard PCB layouts. Verify PCB footprint compatibility before component selection.

Q: What is the significance of the "Last Time Buy" status for BC847BE6327HTSA1?

A: Last Time Buy status indicates the manufacturer has announced discontinuation with a final purchase deadline. This part should not be selected for new designs or long-term production applications. Active-status alternatives such as BC847B-7-F or BC847C-TP are recommended for ongoing production requirements.

Q: How does RoHS compliance affect component selection?

A: The MSD601-ST1 is RoHS non-compliant, indicating it may contain restricted substances. All recommended substitute parts are ROHS3 compliant, meeting current environmental and regulatory requirements. For applications subject to RoHS regulations, ROHS3-compliant substitutes are mandatory.

Q: Can BC847C variants be used in place of BC847A or BC847B variants?

A: BC847C variants feature higher DC current gain (420 @ 2mA, 5V) compared to BC847A (110 @ 2mA, 5V) and BC847B (200 @ 2mA, 5V). While all three are NPN transistors with 45 V ratings and 100 mA maximum current, the higher gain of BC847C may require adjustment of base biasing resistors in current-limited applications. Verify circuit design compatibility before substitution.

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