FSA66P5 Equivalent & Substitute Parts

Part Overview

The FSA66P5 is a single-circuit SPST-NO (Single Pole Single Throw - Normally Open) IC switch manufactured by onsemi in SC-70-5 surface mount packaging. This component functions as an analog switch with a 1:1 multiplexer/demultiplexer configuration, designed for low-voltage signal routing applications with a -3dB bandwidth of 250MHz and charge injection of 0.05pC.

The FSA66P5 is classified as obsolete. Identifying equivalent and substitute parts is necessary to maintain design continuity, ensure supply chain availability, and support ongoing production requirements for applications currently utilizing this component.

Key Parameters

Parameter	FSA66P5 Value
Switch Circuit Type	SPST - NO
Multiplexer/Demultiplexer Configuration	1:1
Number of Circuits	1
Voltage Supply Range (V+)	1.65V ~ 5.5V
-3dB Bandwidth	250MHz
Charge Injection	0.05pC
Channel Capacitance (CS(off), CD(off))	6pF
Operating Temperature Range	-40°C ~ 85°C (TA)
Package / Case	5-TSSOP, SC-70-5, SOT-353
Mounting Type	Surface Mount
Moisture Sensitivity Level (MSL)	1 (Unlimited)

Substitute Part Grouping Explanation

Substitution eligibility for the FSA66P5 is determined by the following critical parameters:

Mandatory Compatibility Criteria:

Switch circuit type: SPST - NO
Multiplexer/demultiplexer configuration: 1:1
Number of circuits: 1
Voltage supply range: Must encompass or be compatible with 1.65V ~ 5.5V
Package / Case: 5-TSSOP, SC-70-5, SOT-353 (or equivalent pin-compatible packages)
Mounting type: Surface Mount

Performance Parameters Affecting Substitution:

On-state resistance (Ron): Lower values provide better signal integrity
-3dB bandwidth: Must meet or exceed application frequency requirements
Charge injection: Lower values reduce signal distortion
Channel capacitance: Affects signal coupling and bandwidth
Operating temperature range: Must cover application environment
Current leakage: Affects power consumption and signal integrity

Substitute parts are grouped based on their on-state resistance characteristics, as this parameter significantly influences switching performance and signal fidelity in analog switch applications.

Parameter Comparison

Part Number	Manufacturer	Ron (Max)	V+ Range	-3dB BW (MHz)	Charge Injection (pC)	CS(off)/CD(off) (pF)	Temp Range (°C)	Package	Status
FSA66P5	onsemi	—	1.65–5.5	250	0.05	6	-40 to 85	SC-70-5	Obsolete
SN74LVC1G66DCKR	Texas Instruments	10Ω	1.65–5.5	300	—	6	-40 to 85	SC-70-5	Active
SN74LVC1G66DCKT	Texas Instruments	10Ω	1.65–5.5	300	—	6	-40 to 85	SC-70-5	Last Time Buy
SN74LVC1G66DRLR	Texas Instruments	10Ω	1.65–5.5	300	—	6	-40 to 85	SOT-553	Active
74LVC1G66GW,125	Nexperia USA Inc.	10Ω	1.65–5.5	500	7.5	6.5	-40 to 125	5-TSSOP	Active
74LVC1G66GV,125	Nexperia USA Inc.	10Ω	1.65–5.5	500	7.5	6.5	-40 to 125	SC-74A	Active
74AHC1G66GW-Q100H	Nexperia USA Inc.	22Ω	2–5.5	280	—	10	-40 to 125	5-TSSOP	Active
74HCT1G66GW-Q100H	Nexperia USA Inc.	95Ω	4.5–5.5	200	—	—	-40 to 125	5-TSSOP	Active
TS5A3166QDCKRQ1	Texas Instruments	900mΩ	1.65–5.5	200	1	19/18	-40 to 125	SC-70-5	Active
ISL43L110IHZ-T	Renesas Electronics	220mΩ (Typ)	1.1–4.5	—	89	68	-40 to 85	SC-70-5	Active

Engineering Selection Recommendations

Primary Substitutes (Highest Compatibility):

The SN74LVC1G66DCKR and SN74LVC1G66DCKT from Texas Instruments provide the closest functional equivalence to the FSA66P5. Both maintain identical voltage supply range (1.65V–5.5V), operating temperature range (-40°C to 85°C), package configuration (SC-70-5), and channel capacitance (6pF). These parts are pin-compatible and electrically interchangeable for the FSA66P5 application space. The SN74LVC1G66DCKR is recommended for new designs due to its Active product status; SN74LVC1G66DCKT is designated Last Time Buy.

Extended Temperature Range Alternatives:

The 74LVC1G66GW,125 and 74LVC1G66GV,125 from Nexperia extend the operating temperature range to -40°C to 125°C while maintaining the 1.65V–5.5V supply voltage compatibility and 10Ω on-state resistance. These parts are suitable for applications requiring enhanced thermal performance. The 74LVC1G66GW,125 is available in 5-TSSOP packaging; the 74LVC1G66GV,125 uses SC-74A packaging.

Automotive-Qualified Alternatives:

The TS5A3166QDCKRQ1 from Texas Instruments carries AEC-Q100 automotive qualification and is suitable for automotive and high-reliability applications. It maintains the 1.65V–5.5V supply range and SC-70-5 package but features higher on-state resistance (900mΩ) and extended temperature range (-40°C to 125°C). This part is appropriate when automotive-grade components are specified.

The 74AHC1G66GW-Q100H from Nexperia also carries AEC-Q100 qualification with extended temperature range (-40°C to 125°C) but operates within a narrower supply voltage range (2V–5.5V) and exhibits higher on-state resistance (22Ω).

Limited Compatibility Options:

The 74HCT1G66GW-Q100H is restricted to 4.5V–5.5V supply voltage operation and is not suitable for applications requiring the full 1.65V–5.5V range of the FSA66P5.

The ISL43L110IHZ-T from Renesas operates within a reduced supply voltage range (1.1V–4.5V) and exhibits significantly higher charge injection (89pC) and channel capacitance (68pF), making it unsuitable for direct substitution in bandwidth-sensitive applications.

Frequently Asked Questions (FAQ)

Q: Can the SN74LVC1G66DCKR directly replace the FSA66P5 without PCB modifications?

A: Yes. The SN74LVC1G66DCKR is pin-compatible with the FSA66P5 in SC-70-5 packaging. Both parts share identical pin assignments, voltage supply range (1.65V–5.5V), operating temperature range (-40°C to 85°C), and channel capacitance (6pF). No PCB layout changes are required.

Q: What is the primary difference between the 74LVC1G66 series and the FSA66P5?

A: The 74LVC1G66 series from Texas Instruments and Nexperia specifies a maximum on-state resistance of 10Ω, whereas the FSA66P5 does not provide this specification. The 74LVC1G66 parts offer defined switching performance characteristics and are available in Active product status, making them suitable for new designs and long-term supply continuity.

Q: Why does the 74HCT1G66GW-Q100H have a narrower supply voltage range?

A: The 74HCT1G66GW-Q100H is designed for TTL-compatible logic levels and operates within the 4.5V–5.5V range. The FSA66P5 and most recommended substitutes support the broader 1.65V–5.5V range for CMOS and low-voltage applications. Select the 74HCT1G66GW-Q100H only if your application operates exclusively at 5V supply voltage.

Q: Is the TS5A3166QDCKRQ1 suitable for non-automotive applications?

A: Yes. The TS5A3166QDCKRQ1 is a general-purpose SPST-NO switch with AEC-Q100 automotive qualification. It is fully functional in non-automotive applications and offers extended temperature range (-40°C to 125°C) and automotive-grade reliability. However, its 900mΩ on-state resistance is significantly higher than the FSA66P5 and may not be suitable for low-impedance signal routing applications.

Q: What packaging options are available for LVC1G66 substitutes?

A: The 74LVC1G66 series is available in multiple packages: SC-70-5 (SN74LVC1G66DCKR), SOT-553 (SN74LVC1G66DRLR), 5-TSSOP (74LVC1G66GW,125), and SC-74A (74LVC1G66GV,125). Select the package variant that matches your PCB design requirements and assembly capabilities.

Q: Can I use the ISL43L110IHZ-T as a direct replacement?

A: The ISL43L110IHZ-T is not recommended as a direct replacement. Although it shares SC-70-5 packaging and SPST-NO functionality, it operates within a reduced supply voltage range (1.1V–4.5V), exhibits significantly higher charge injection (89pC), and features substantially higher channel capacitance (68pF). These characteristics make it unsuitable for applications requiring the FSA66P5's performance envelope.

Q: What is the difference between Cut Tape and Tape & Reel packaging?

A: Cut Tape (CT) and Digi-Reel® packaging are supplied in smaller quantities suitable for prototyping and low-volume production. Tape & Reel (TR) packaging is supplied in larger quantities on continuous tape reels for high-volume automated assembly. Both packaging formats contain identical components; the difference is in supply quantity and handling method.

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