FSA266L8X Equivalent & Substitute Parts Reference

Part Overview

The FSA266L8X is a 2-circuit IC switch with SPST-NO configuration manufactured by onsemi. This component features 10Ohm on-state resistance, 1:1 multiplexer/demultiplexer circuit topology, and operates across a 1.65V to 5.5V supply voltage range. The part is classified as obsolete, making identification of functionally equivalent alternatives essential for ongoing design support and procurement planning.

Key Parameters

Parameter	Value
Switch Circuit Type	SPST - NO
Number of Circuits	2
Multiplexer/Demultiplexer Configuration	1:1
On-State Resistance (Max)	10Ohm
Channel-to-Channel Matching (ΔRon)	200mOhm
Supply Voltage Range (V+)	1.65V ~ 5.5V
Switch Time (Ton/Toff Max)	3.2ns / 4.1ns
-3dB Bandwidth	300MHz
Channel Capacitance (CS(off), CD(off))	5pF
Leakage Current (IS(off) Max)	100nA
Crosstalk	-70dB @ 10MHz
Operating Temperature Range	-40°C ~ 85°C
Package Type	8-UFQFN (8-MicroPak™)
Mounting Type	Surface Mount
RoHS Status	ROHS3 Compliant
Moisture Sensitivity Level	1 (Unlimited)

Substitute Part Grouping Explanation

Substitution eligibility for the FSA266L8X is determined by the following critical parameters:

Primary Equivalence Criteria:

Switch circuit topology (SPST - NO)
Number of circuits (2)
Multiplexer/demultiplexer configuration (1:1)
On-state resistance specification (10Ohm maximum)
Supply voltage compatibility (1.65V ~ 5.5V range)
Package form factor (8-pin surface mount)
RoHS3 compliance status

Secondary Compatibility Factors:

Switch timing characteristics (Ton/Toff)
Bandwidth performance (-3dB Bandwidth)
Channel capacitance values
Leakage current specifications
Operating temperature range

The NC7WB66L8X qualifies as a parametric equivalent, matching all primary criteria including identical on-state resistance, supply voltage range, and package configuration. The NX3L2T66GM,125 is classified as a similar part with functional compatibility in SPST-NO 2-circuit topology but exhibits different electrical characteristics in resistance, timing, and bandwidth parameters.

Parameter Comparison

Parameter	FSA266L8X (Main)	NC7WB66L8X (Parametric Equivalent)	NX3L2T66GM,125 (Similar)
Manufacturer	onsemi	onsemi	NXP Semiconductors
Switch Circuit	SPST - NO	SPST - NO	SPST - NO
Number of Circuits	2	2	2
Multiplexer Configuration	1:1	1:1	1:1
On-State Resistance (Max)	10Ohm	10Ohm	750mOhm
Channel-to-Channel Matching (ΔRon)	200mOhm	200mOhm	20mOhm
Supply Voltage (V+)	1.65V ~ 5.5V	1.65V ~ 5.5V	1.4V ~ 4.3V
Switch Time Ton (Max)	3.2ns	3.2ns	28ns
Switch Time Toff (Max)	4.1ns	4.1ns	20ns
-3dB Bandwidth	300MHz	300MHz	60MHz
Channel Capacitance (CS(off), CD(off))	5pF	5pF	35pF
Leakage Current (IS(off) Max)	100nA	100nA	10nA
Crosstalk	-70dB @ 10MHz	-70dB @ 10MHz	-90dB @ 100kHz
Operating Temperature	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 125°C
Package / Case	8-UFQFN	8-UFQFN	8-XFQFN Exposed Pad
Packaging Format	Tape & Reel (TR)	Cut Tape (CT) & Digi-Reel®	Cut Tape (CT)
Product Status	Obsolete	Obsolete	Discontinued at DiGi Electronics
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Moisture Sensitivity Level	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)

Engineering Selection Recommendations

NC7WB66L8X - Parametric Equivalent: The NC7WB66L8X is the direct parametric equivalent for FSA266L8X replacement. Both parts share identical electrical specifications across all critical parameters: 10Ohm on-state resistance, 1.65V to 5.5V supply voltage range, 3.2ns/4.1ns switching times, 300MHz bandwidth, and 5pF channel capacitance. Both maintain ROHS3 compliance and MSL 1 rating. The primary distinction is packaging format (Cut Tape & Digi-Reel® versus Tape & Reel). This part is suitable for direct substitution in applications requiring identical electrical performance.

NX3L2T66GM,125 - Similar Alternative: The NX3L2T66GM,125 from NXP Semiconductors provides functional compatibility as a 2-circuit SPST-NO switch but with different electrical characteristics. The 750mOhm on-state resistance is significantly higher than the 10Ohm specification of the main part, resulting in different signal path impedance and power dissipation profiles. Supply voltage range is narrower (1.4V to 4.3V), and switching times are substantially slower (28ns/20ns versus 3.2ns/4.1ns). Bandwidth is reduced to 60MHz. This part is suitable only for applications where the lower on-state resistance and higher bandwidth of the FSA266L8X are not critical requirements. The extended operating temperature range (-40°C to 125°C) and improved leakage current (10nA) may provide advantages in specific thermal or low-power applications.

All substitute parts maintain ROHS3 compliance and unlimited moisture sensitivity rating, ensuring regulatory consistency with the original component.

Frequently Asked Questions (FAQ)

Q: Can NC7WB66L8X be used as a direct replacement for FSA266L8X? A: Yes. The NC7WB66L8X is a parametric equivalent with identical electrical specifications. All critical parameters including on-state resistance (10Ohm), supply voltage range (1.65V ~ 5.5V), switching times (3.2ns/4.1ns), and bandwidth (300MHz) match the FSA266L8X. The only difference is packaging format. No circuit redesign is required.

Q: What are the limitations of using NX3L2T66GM,125 as a substitute? A: The NX3L2T66GM,125 has significantly different electrical characteristics. On-state resistance is 750mOhm (versus 10Ohm), switching times are slower (28ns/20ns versus 3.2ns/4.1ns), and bandwidth is reduced to 60MHz. Supply voltage range is also narrower (1.4V ~ 4.3V). This part is suitable only for applications where these performance differences are acceptable.

Q: Are there package compatibility issues between FSA266L8X and NC7WB66L8X? A: Both parts use the 8-UFQFN (8-MicroPak™) package with identical pin configuration and footprint. Package compatibility is confirmed. The difference in packaging format (Tape & Reel versus Cut Tape & Digi-Reel®) affects procurement and handling but not PCB assembly.

Q: What is the difference between the packaging formats listed? A: FSA266L8X is supplied in Tape & Reel (TR) format for high-volume automated assembly. NC7WB66L8X is available in Cut Tape (CT) and Digi-Reel® format, suitable for lower-volume or mixed-component orders. Both formats contain the same component in the same package; the difference is in the carrier medium and quantity per reel.

Q: Does the NX3L2T66GM,125 have any advantages over the FSA266L8X? A: The NX3L2T66GM,125 offers lower leakage current (10nA versus 100nA), better channel-to-channel matching (20mOhm versus 200mOhm), and extended operating temperature range (-40°C to 125°C versus -40°C to 85°C). However, these advantages come with trade-offs in on-state resistance, switching speed, and bandwidth. Selection depends on application-specific requirements.

Q: Are all substitute parts RoHS3 compliant? A: Yes. FSA266L8X, NC7WB66L8X, and NX3L2T66GM,125 are all ROHS3 compliant with MSL 1 (Unlimited) moisture sensitivity rating, ensuring regulatory consistency across all options.

Q: What should I consider when selecting between these parts? A: Evaluate your application requirements for on-state resistance, switching speed, bandwidth, and supply voltage range. For applications requiring the full 10Ohm resistance and 300MHz bandwidth, use NC7WB66L8X. For applications with relaxed speed and resistance requirements but needing extended temperature range or lower leakage, consider NX3L2T66GM,125. Verify supply voltage compatibility in all cases.

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