FSA66M5 Equivalent & Substitute Parts Reference

Part Overview

The FSA66M5 is a single-circuit SPST-NO (Single Pole Single Throw - Normally Open) IC switch manufactured by onsemi in SOT-23-5 surface mount packaging. This component operates across a supply voltage range of 1.65V to 5.5V with a -3dB bandwidth of 250MHz and charge injection of 0.05pC, making it suitable for analog signal switching and multiplexing applications in low-voltage systems.

The FSA66M5 is classified as obsolete. Equivalent and substitute parts are necessary to maintain design continuity, ensure supply chain availability, and support ongoing production requirements for applications currently utilizing this component.

Substiute Parts

FSA66M5

onsemiIn Stock: 1044FSA66M5 Datasheet

Current PartRFQ

SN74LVC1G66DBVR

Texas InstrumentsIn Stock: 35169SN74LVC1G66DBVR Datasheet

DirectRFQ

74AHC1G66GV,125

Nexperia USA Inc.In Stock: 4835974AHC1G66GV,125 Datasheet

SimilarRFQ

74AHC1G66GV-Q100H

Nexperia USA Inc.In Stock: 3911974AHC1G66GV-Q100H Datasheet

SimilarRFQ

74AHCT1G66GV,125

Nexperia USA Inc.In Stock: 210674AHCT1G66GV,125 Datasheet

SimilarRFQ

74HC1G66GV,125

Nexperia USA Inc.In Stock: 275874HC1G66GV,125 Datasheet

SimilarRFQ

74HCT1G66GV,125

Nexperia USA Inc.In Stock: 75274HCT1G66GV,125 Datasheet

SimilarRFQ

74LVC1G66GV,125

Nexperia USA Inc.In Stock: 984874LVC1G66GV,125 Datasheet

SimilarRFQ

BU4S66G2-TR

Rohm SemiconductorIn Stock: 86276BU4S66G2-TR Datasheet

SimilarRFQ

SN74AUC1G66DBVR

Texas InstrumentsIn Stock: 3214SN74AUC1G66DBVR Datasheet

SimilarRFQ

SN74LVC1G66DBVT

Texas InstrumentsIn Stock: 2121SN74LVC1G66DBVT Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution of the FSA66M5 is determined by strict adherence to the following electrical and mechanical parameters:

Critical Substitution Criteria:

• Switch circuit type must be SPST - NO
• Multiplexer/Demultiplexer circuit configuration must be 1:1
• Number of circuits must be 1
• Supply voltage range must encompass or be compatible with 1.65V ~ 5.5V
• Operating temperature range must support -40°C ~ 85°C minimum
• Mounting type must be Surface Mount
• Package must be SC-74A, SOT-753 or SOT-23-5 compatible

Secondary Compatibility Parameters:

• -3dB Bandwidth: 250MHz or higher preferred for signal integrity
• Charge Injection: Lower values preferred (0.05pC reference)
• Channel Capacitance: 6pF to 10pF acceptable range
• Moisture Sensitivity Level: MSL 1 required

Substitute parts are grouped into two categories: Direct Substitutes (pin-compatible, functionally equivalent) and Similar Substitutes (compatible electrical function with minor parameter variations requiring design verification).

Parameter Comparison

Engineering Selection Recommendations

Primary Recommendation: SN74LVC1G66DBVR (Texas Instruments)

The SN74LVC1G66DBVR is the optimal direct substitute for the FSA66M5. This part maintains identical supply voltage range (1.65V ~ 5.5V), identical operating temperature range (-40°C ~ 85°C), and identical package configuration (SOT-23-5). The component offers superior -3dB bandwidth (300MHz vs. 250MHz) and lower on-state resistance (10Ohm), providing enhanced performance characteristics. Product status is Active with robust inventory availability (35,088 units), ensuring long-term supply chain stability. RoHS3 compliance and REACH Unaffected status satisfy regulatory requirements.

Secondary Recommendation: 74LVC1G66GV,125 (Nexperia USA Inc.)

The 74LVC1G66GV,125 provides functional equivalence with extended operating temperature range (-40°C ~ 125°C) and superior -3dB bandwidth (500MHz). This part is available in SC-74A package and maintains the 1.65V ~ 5.5V supply voltage compatibility. Product status is Active with substantial inventory (9,801 units). This option is suitable for applications requiring enhanced thermal performance or higher bandwidth operation.

Alternative for Extended Voltage Range: BU4S66G2-TR (Rohm Semiconductor)

The BU4S66G2-TR accommodates extended supply voltage range (3V ~ 18V) and maintains operating temperature compatibility (-40°C ~ 85°C). This part is appropriate for applications requiring higher supply voltage operation. Product status is Active with high inventory availability (86,200 units). Note: Package is 5-SSOP, requiring PCB layout modification from SOT-23-5.

Not Recommended: SN74AUC1G66DBVR

The SN74AUC1G66DBVR operates at reduced supply voltage range (0.8V ~ 2.7V), which does not encompass the FSA66M5 specification of 1.65V ~ 5.5V. This part is unsuitable for direct substitution in applications requiring the full voltage range of the original component.

Not Recommended: 74AHCT1G66GV,125 and 74HCT1G66GV,125

These parts operate at restricted supply voltage range (4.5V ~ 5.5V), which does not support the lower voltage operation of the FSA66M5 (1.65V minimum). These options are unsuitable for low-voltage applications.

Frequently Asked Questions (FAQ)

Q: Can the SN74LVC1G66DBVR be used as a direct pin-for-pin replacement for the FSA66M5?

A: Yes. Both components utilize SOT-23-5 packaging with identical pin configuration. The SN74LVC1G66DBVR maintains the same supply voltage range (1.65V ~ 5.5V) and operating temperature range (-40°C ~ 85°C), enabling direct substitution without circuit modification.

Q: What is the primary difference between the SN74LVC1G66DBVR and 74LVC1G66GV,125?

A: The primary difference is package configuration. The SN74LVC1G66DBVR uses SOT-23-5 packaging (direct replacement for FSA66M5), while the 74LVC1G66GV,125 uses SC-74A packaging. Both maintain identical electrical specifications and supply voltage range. Selection depends on PCB layout compatibility.

Q: Why is the SN74AUC1G66DBVR not recommended as a substitute?

A: The SN74AUC1G66DBVR operates at supply voltage range 0.8V ~ 2.7V, which does not encompass the FSA66M5 specification of 1.65V ~ 5.5V. Applications requiring operation at voltages below 2.7V or above 2.7V cannot use this component as a substitute.

Q: Does the BU4S66G2-TR require any design modifications for substitution?

A: Yes. The BU4S66G2-TR uses 5-SSOP packaging, whereas the FSA66M5 uses SOT-23-5 packaging. PCB layout and footprint modifications are required. Additionally, the extended supply voltage range (3V ~ 18V) may require circuit design review if the application operates below 3V.

Q: Are all recommended substitutes RoHS3 compliant?

A: Yes. All active substitute parts listed (SN74LVC1G66DBVR, 74AHC1G66GV,125, 74AHC1G66GV-Q100H, 74AHCT1G66GV,125, 74HC1G66GV,125, 74HCT1G66GV,125, 74LVC1G66GV,125, BU4S66G2-TR, and SN74AUC1G66DBVR) are RoHS3 compliant and REACH Unaffected.

Q: What is the significance of the charge injection parameter in selecting a substitute?

A: Charge injection affects signal integrity in analog switching applications. The FSA66M5 specifies 0.05pC charge injection. The 74LVC1G66GV,125 specifies 7.5pC, which is higher but acceptable for most applications. For precision analog switching requiring minimal charge injection, the SN74LVC1G66DBVR (charge injection not specified but typically lower in LVC series) is preferred.

Q: Can the 74AHCT1G66GV,125 be used in applications operating at 1.65V?

A: No. The 74AHCT1G66GV,125 specifies minimum supply voltage of 4.5V. This part cannot operate at the FSA66M5 minimum voltage of 1.65V and is unsuitable for low-voltage applications.

Q: What inventory considerations should guide substitute selection?

A: The SN74LVC1G66DBVR offers the highest inventory availability (35,088 units), followed by BU4S66G2-TR (86,200 units) and 74LVC1G66GV,125 (9,801 units). For applications requiring immediate availability and long-term supply assurance, the SN74LVC1G66DBVR is the optimal choice.