FSA4157AP6X Equivalent & Substitute Parts

Part Overview

The FSA4157AP6X is a single-circuit SPDT (Single Pole Double Throw) analog switch manufactured by onsemi, housed in a 6-pin SC-88 (SOT-363) surface mount package. This device operates as a 2:1 multiplexer/demultiplexer with an on-state resistance of 1.15Ω maximum and supports supply voltages from 2.7V to 5.5V. The part is currently in active production status with 12,200 units in stock.

Equivalent and substitute parts are necessary when the primary device becomes unavailable, when design requirements demand alternative electrical characteristics, or when supply chain optimization requires component standardization across manufacturing facilities.

Key Parameters

Parameter	FSA4157AP6X
Switch Circuit Configuration	SPDT
Multiplexer/Demultiplexer Circuit	2:1
Number of Circuits	1
On-State Resistance (Max)	1.15Ω
Channel-to-Channel Matching (ΔRon)	60mΩ
Supply Voltage Range (V+)	2.7V – 5.5V
Switch Time (Ton/Toff Max)	35ns / 15ns
-3dB Bandwidth	300MHz
Charge Injection	20pC
Channel Capacitance (CS(off) / CD(off))	12pF
Leakage Current (IS(off) Max)	2nA (Typ)
Crosstalk	-70dB @ 1MHz
Operating Temperature Range	-40°C to +85°C
Package / Case	6-TSSOP, SC-88, SOT-363
Product Status	Active
RoHS Compliance	ROHS3 Compliant
Moisture Sensitivity Level	1 (Unlimited)

Substitute Part Grouping Explanation

Substitution eligibility for the FSA4157AP6X is determined by the following mandatory criteria:

Primary Compatibility Requirements:

Switch circuit configuration: SPDT
Multiplexer/demultiplexer circuit: 2:1
Number of circuits: 1
Package type: 6-pin surface mount (SC-88, SOT-363, or equivalent footprint)
Mounting type: Surface mount

Electrical Performance Boundaries:

On-state resistance: Must not exceed application requirements; lower values provide improved signal integrity
Supply voltage range: Must encompass or exceed 2.7V – 5.5V minimum operating window
Operating temperature: Must support -40°C to +85°C minimum range
Leakage current: Lower values preferred for signal fidelity
Crosstalk performance: -70dB @ 1MHz or better maintains signal isolation

Compliance Requirements:

RoHS3 compliance mandatory
MSL rating 1 (Unlimited) required
REACH unaffected status required

Substitute parts are grouped by electrical performance tier: low-resistance devices (≤1.2Ω), mid-range devices (5.5Ω – 8Ω), and higher-resistance devices (11Ω – 15Ω). Selection depends on application impedance matching and signal path requirements.

Parameter Comparison

Part Number	Manufacturer	On-State Resistance (Max)	ΔRon (Max)	Supply Voltage (V+)	Switch Time Ton/Toff (Max)	-3dB Bandwidth	Leakage Current (Max)	Crosstalk	Operating Temp	Product Status
FSA4157AP6X	onsemi	1.15Ω	60mΩ	2.7V – 5.5V	35ns / 15ns	300MHz	2nA (Typ)	-70dB @ 1MHz	-40°C to +85°C	Active
TS5A3159DCKR	Texas Instruments	1.1Ω	100mΩ	1.65V – 5.5V	35ns / 20ns	100MHz	2nA	-65dB @ 1MHz	-40°C to +85°C	Active
PI5A4157CEX	Diodes Incorporated	1.2Ω	10mΩ	1.65V – 5.5V	18ns / 20ns	150MHz	20nA	-70dB @ 1MHz	-40°C to +85°C	Last Time Buy
MAX4730EXT+T	Analog Devices Inc./Maxim Integrated	5.5Ω	50mΩ	1.8V – 5.5V	45ns / 26ns	300MHz	2nA	-67dB @ 1MHz	-40°C to +85°C	Active
DG2002EDL-T1-GE3	Vishay Siliconix	8Ω	40mΩ (Typ)	1.8V – 5.5V	30ns / 24ns	Not specified	1.5nA	-77dB @ 1MHz	-40°C to +85°C	Active
PI5A3157BC6EX	Diodes Incorporated	11Ω	150mΩ	1.65V – 5.5V	5.2ns / 4.5ns	350MHz	100nA	-64dB @ 10MHz	-40°C to +85°C	Active
PI5A3157CEX	Diodes Incorporated	13Ω	150mΩ	1.65V – 5.5V	5.2ns / 4.6ns	250MHz	100nA	-54dB @ 10MHz	-40°C to +85°C	Active
SN74LVC1G3157DCKR	UMW	7Ω (Typ)	150mΩ (Typ)	1.65V – 5.5V	5.2ns / 4.6ns	350MHz	100nA (Max)	Not specified	-55°C to +125°C	Active
STG3157CTR	STMicroelectronics	15Ω	100mΩ	1.65V – 4.3V	15ns / 10ns	250MHz	100nA	-55dB @ 10MHz	-55°C to +125°C	Active
1P1G3157QDCKRQ1	Texas Instruments	15Ω	100mΩ	1.65V – 5.5V	5.7ns / 3.8ns	300MHz	1µA	-54dB @ 10MHz	-40°C to +125°C	Active (AEC-Q100)
NLVASB3157DFT2G	onsemi	7Ω (Typ)	500mΩ	1.65V – 5.5V	Not specified	250MHz	100nA	-54dB @ 10MHz	-55°C to +125°C	Obsolete

Engineering Selection Recommendations

Direct Substitutes (Lowest Resistance Tier):

TS5A3159DCKR and PI5A4157CEX are the closest electrical equivalents to FSA4157AP6X, both offering on-state resistance values within 0.05Ω of the original device. TS5A3159DCKR maintains active production status and identical operating temperature range. PI5A4157CEX exhibits superior channel-to-channel matching (10mΩ vs. 60mΩ) but carries Last Time Buy status, indicating limited future availability.

Performance-Optimized Alternatives (Mid-Resistance Tier):

MAX4730EXT+T and DG2002EDL-T1-GE3 provide moderate resistance increases (5.5Ω and 8Ω respectively) while maintaining 300MHz bandwidth and superior crosstalk performance (-67dB and -77dB). These devices suit applications where impedance matching is less critical and lower leakage current is beneficial.

Extended Temperature Range Options:

SN74LVC1G3157DCKR and STG3157CTR support operating temperatures to -55°C to +125°C, exceeding the FSA4157AP6X specification. SN74LVC1G3157DCKR offers 350MHz bandwidth with 7Ω typical resistance. STG3157CTR operates at reduced maximum supply voltage (4.3V upper limit) and carries higher on-state resistance (15Ω).

Automotive-Grade Alternative:

1P1G3157QDCKRQ1 from Texas Instruments carries AEC-Q100 qualification and maintains full 5.5V supply range with 300MHz bandwidth, suitable for automotive applications requiring extended temperature operation (-40°C to +125°C).

Obsolete Part:

NLVASB3157DFT2G is marked obsolete and should not be selected for new designs despite onsemi manufacturer origin.

Frequently Asked Questions (FAQ)

Q: Can I use a substitute part with higher on-state resistance than the FSA4157AP6X?

A: Yes, provided the application circuit tolerates the increased resistance. Higher resistance values (5.5Ω to 15Ω) introduce greater signal attenuation and voltage drop across the switch. Verify that your signal path impedance and load requirements accommodate the substitute device's Ron specification.

Q: What is the significance of channel-to-channel matching (ΔRon)?

A: ΔRon represents the maximum resistance variation between the two switch channels. Lower values (10mΩ to 60mΩ) ensure balanced signal routing and are critical for stereo audio, differential signal switching, and precision analog multiplexing. Higher values (150mΩ to 500mΩ) may introduce channel imbalance in sensitive applications.

Q: Are all substitute parts compatible with the SC-88 package footprint?

A: All listed substitutes use 6-pin surface mount packages (SC-88, SOT-363, or SOT-323-6L). While these packages share similar pin spacing and land patterns, verify PCB layout compatibility with your specific footprint library before committing to production.

Q: Which substitute offers the best crosstalk performance?

A: DG2002EDL-T1-GE3 from Vishay Siliconix provides the lowest crosstalk at -77dB @ 1MHz, followed by FSA4157AP6X and PI5A4157CEX at -70dB @ 1MHz. Crosstalk becomes critical in high-frequency multiplexing applications above 100MHz.

Q: Can I use PI5A4157CEX as a long-term replacement?

A: PI5A4157CEX carries Last Time Buy status, indicating onsemi has announced end-of-life production. While current inventory (5,962 units) may support near-term requirements, this part is unsuitable for designs requiring multi-year component availability. Select TS5A3159DCKR or MAX4730EXT+T for sustained production.

Q: What is the minimum supply voltage requirement for substitutes?

A: FSA4157AP6X operates from 2.7V minimum. Most substitutes (TS5A3159DCKR, PI5A4157CEX, SN74LVC1G3157DCKR, STG3157CTR, 1P1G3157QDCKRQ1) support 1.65V minimum, providing greater flexibility in low-voltage applications. MAX4730EXT+T and DG2002EDL-T1-GE3 require 1.8V minimum.

Q: Is RoHS3 compliance maintained across all substitutes?

A: Yes. All listed substitute parts carry ROHS3 Compliant status with MSL rating 1 (Unlimited) and REACH Unaffected designation, meeting current environmental and regulatory requirements.

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