FST3383QSCX Bus FET Exchange Switch Equivalent & Substitute Parts

Part Overview

The FST3383QSCX is a Bus FET Exchange Switch manufactured by onsemi, designed for 5 x 2:2 switching applications in 24-QSOP packaging. This component operates as a single-supply logic device with a voltage range of 4V to 5.5V and supports operating temperatures from -40°C to 85°C. The FST3383QSCX is currently classified as obsolete, making equivalent substitute parts necessary for ongoing design support and procurement.

Key Parameters

Parameter	Value
Manufacturer Part Number	FST3383QSCX
Manufacturer	onsemi
Product Type	Bus FET Exchange Switch
Circuit Configuration	5 x 2:2
Voltage Supply Range	4V ~ 5.5V
Operating Temperature Range	-40°C ~ 85°C
Mounting Type	Surface Mount
Package / Case	24-SSOP (0.154", 3.90mm Width)
Supplier Device Package	24-QSOP
Product Status	Obsolete
Moisture Sensitivity Level	1 (Unlimited)

Substitute Part Grouping Explanation

Substitution eligibility for the FST3383QSCX is determined by the following critical parameters:

Circuit Configuration: Must be 5 x 2:2 topology
Voltage Supply Range: Must support the operating range of 4V to 5.5V (or compatible subset)
Operating Temperature Range: Must support -40°C to 85°C
Mounting Type: Surface Mount required
Package Compatibility: 24-pin SSOP/QSOP/TSSOP variants acceptable

Substitute parts are grouped into two categories based on package type: 24-SSOP variants (QS3383QG, QS3383QG8, SN74CBT3383CDBQR, SN74CBT3383DBQR, SN74CBT3383DBR) and 24-TSSOP variants (SN74CBT3383CPWR, SN74CBT3383PW, SN74CBT3383PWR). The 24-TVSOP variant (SN74CBT3383DGVR) represents an alternative package option. All substitute parts maintain identical circuit functionality and electrical specifications within their respective voltage and temperature ranges.

Parameter Comparison

Part Number	Manufacturer	Circuit	Voltage Supply	Temp Range	Package	Product Status	RoHS Status	MSL
FST3383QSCX	onsemi	5 x 2:2	4V ~ 5.5V	-40°C ~ 85°C	24-QSOP	Obsolete	Not specified	1
QS3383QG	Renesas Electronics	5 x 2:2	4.75V ~ 5.25V	-40°C ~ 85°C	24-QSOP	Active	ROHS3 Compliant	1
QS3383QG8	Renesas Electronics	5 x 2:2	4.75V ~ 5.25V	-40°C ~ 85°C	24-QSOP	Active	ROHS3 Compliant	1
SN74CBT3383CDBQR	Texas Instruments	5 x 2:2	4.5V ~ 5.5V	-40°C ~ 85°C	24-SSOP	Active	ROHS3 Compliant	2
SN74CBT3383CPWR	Texas Instruments	5 x 2:2	4.5V ~ 5.5V	-40°C ~ 85°C	24-TSSOP	Active	ROHS3 Compliant	1
SN74CBT3383DBQR	Texas Instruments	5 x 2:2	4.5V ~ 5.5V	-40°C ~ 85°C	24-SSOP	Active	ROHS3 Compliant	2
SN74CBT3383DBR	Texas Instruments	5 x 2:2	4.5V ~ 5.5V	-40°C ~ 85°C	24-SSOP	Last Time Buy	ROHS3 Compliant	1
SN74CBT3383DGVR	Texas Instruments	5 x 2:2	4.5V ~ 5.5V	-40°C ~ 85°C	24-TVSOP	Discontinued at DiGi Electronics	ROHS3 Compliant	1
SN74CBT3383PW	Texas Instruments	5 x 2:2	4.5V ~ 5.5V	-40°C ~ 85°C	24-TSSOP	Last Time Buy	ROHS3 Compliant	1
SN74CBT3383PWR	Texas Instruments	5 x 2:2	4.5V ~ 5.5V	-40°C ~ 85°C	24-TSSOP	Last Time Buy	ROHS3 Compliant	1

Engineering Selection Recommendations

For new designs, QS3383QG and QS3383QG8 from Renesas Electronics are preferred substitutes due to their Active product status and ROHS3 compliance. Both parts maintain the same 24-QSOP package as the original FST3383QSCX and support the required operating temperature range.

For designs requiring 24-SSOP packaging, SN74CBT3383CDBQR and SN74CBT3383DBQR from Texas Instruments are Active products with ROHS3 compliance. SN74CBT3383DBQR offers MSL 1 rating, providing superior moisture handling compared to SN74CBT3383CDBQR (MSL 2).

For 24-TSSOP packaging, SN74CBT3383CPWR is the only Active product option and is recommended for new designs. SN74CBT3383PW and SN74CBT3383PWR are classified as Last Time Buy and should not be selected for new production.

SN74CBT3383DGVR (24-TVSOP) is discontinued at DiGi Electronics and is not recommended for new designs.

Frequently Asked Questions (FAQ)

Q: Can QS3383QG replace FST3383QSCX directly? A: Yes. Both parts share identical 5 x 2:2 circuit configuration, 24-QSOP packaging, and -40°C to 85°C operating temperature range. The QS3383QG voltage supply range (4.75V ~ 5.25V) is a subset of the FST3383QSCX range (4V ~ 5.5V), making it compatible for applications operating within 4.75V to 5.25V.

Q: What is the difference between 24-QSOP, 24-SSOP, and 24-TSSOP packages? A: These are distinct surface-mount package types with different physical dimensions. 24-QSOP and 24-SSOP both have 0.154" width (3.90mm), while 24-TSSOP has 0.173" width (4.40mm). Package selection depends on PCB layout constraints and available footprint space. Parts cannot be interchanged between different package types without PCB redesign.

Q: Are all substitute parts ROHS3 compliant? A: All substitute parts listed are ROHS3 compliant. The original FST3383QSCX RoHS status is not specified in available documentation.

Q: Which substitute offers the best moisture sensitivity rating? A: Parts with MSL 1 (Unlimited) rating provide superior moisture handling: QS3383QG, QS3383QG8, SN74CBT3383CPWR, SN74CBT3383DBR, SN74CBT3383DGVR, SN74CBT3383PW, and SN74CBT3383PWR. Parts with MSL 2 (1 Year) rating include SN74CBT3383CDBQR and SN74CBT3383DBQR.

Q: Can I use Last Time Buy parts in new designs? A: Last Time Buy parts (SN74CBT3383DBR, SN74CBT3383PW, SN74CBT3383PWR) should not be selected for new production designs. These parts have limited availability and will eventually become unavailable. Active status parts are recommended for new designs.

Q: What voltage range should I verify for my application? A: Verify your application's operating voltage range against the substitute part's voltage specification. Renesas QS3383 series supports 4.75V ~ 5.25V, while Texas Instruments SN74CBT3383 series supports 4.5V ~ 5.5V. Select the part whose voltage range encompasses your application requirements.

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