FST3245MTC Equivalent & Substitute Parts

Part Overview

The FST3245MTC is an 8x1:1 bus switch logic IC manufactured by onsemi in a 20-TSSOP package. This component is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement. The FST3245MTC operates as a single-supply bus switch with a voltage range of 4V to 5.5V and temperature range of -40°C to 85°C, suitable for applications requiring multiplexing or isolation of digital bus signals.

Key Parameters

Parameter	Value
Manufacturer Part Number	FST3245MTC
Manufacturer	onsemi
Type	Bus Switch
Circuit Configuration	8 x 1:1
Independent Circuits	1
Voltage Supply Source	Single Supply
Voltage - Supply Range	4V ~ 5.5V
Operating Temperature Range	-40°C ~ 85°C
Mounting Type	Surface Mount
Package / Case	20-TSSOP (0.173", 4.40mm Width)
Moisture Sensitivity Level (MSL)	1 (Unlimited)
REACH Status	REACH Unaffected

Substitute Part Grouping Explanation

Substitution for the FST3245MTC is determined by the following critical parameters:

Functional Equivalence: All substitute parts must implement an 8x1:1 bus switch configuration with a single independent circuit.

Electrical Compatibility: Supply voltage range and operating temperature range must support the application requirements. Parts with overlapping or wider voltage ranges (4V–5.5V or 4.75V–5.25V) are functionally compatible.

Package Compatibility: The original 20-TSSOP package can be substituted with equivalent packages including 20-TSSOP, 20-SSOP, 20-QSOP, and 20-TVSOP, provided PCB layout accommodates the physical dimensions.

Regulatory Compliance: REACH Unaffected status and RoHS3 compliance are maintained across all substitute parts.

Product Status Consideration: While the main part is obsolete, substitute parts span Last Time Buy and Active statuses, providing procurement flexibility.

Parameter Comparison

Part Number	Manufacturer	Circuit	Voltage Supply (V)	Temp Range (°C)	Package	Product Status	RoHS Status
FST3245MTC	onsemi	8 x 1:1	4.0 ~ 5.5	-40 ~ 85	20-TSSOP	Obsolete	Not specified
FST3245MTCX	onsemi	8 x 1:1	4.0 ~ 5.5	-40 ~ 85	20-TSSOP	Obsolete	ROHS3 Compliant
PI5C3245LE	Diodes Incorporated	8 x 1:1	4.75 ~ 5.25	-40 ~ 85	20-TSSOP	Last Time Buy	ROHS3 Compliant
PI5C3245LEX	Diodes Incorporated	8 x 1:1	4.75 ~ 5.25	-40 ~ 85	20-TSSOP	Last Time Buy	ROHS3 Compliant
PI5C3245QEX	Diodes Incorporated	8 x 1:1	4.75 ~ 5.25	-40 ~ 85	20-QSOP	Last Time Buy	ROHS3 Compliant
SN74CBT3245ADBR	Texas Instruments	8 x 1:1	4.0 ~ 5.5	-40 ~ 85	20-SSOP	Last Time Buy	ROHS3 Compliant
SN74CBT3245ADGVR	Texas Instruments	8 x 1:1	4.0 ~ 5.5	-40 ~ 85	20-TVSOP	Last Time Buy	ROHS3 Compliant
SN74CBT3245APWR	Texas Instruments	8 x 1:1	4.0 ~ 5.5	-40 ~ 85	20-TSSOP	Last Time Buy	ROHS3 Compliant
SN74CBT3245CDBQR	Texas Instruments	8 x 1:1	4.0 ~ 5.5	-40 ~ 85	20-SSOP	Active	ROHS3 Compliant
SN74CBT3245CDBR	Texas Instruments	8 x 1:1	4.0 ~ 5.5	-40 ~ 85	20-SSOP	Active	ROHS3 Compliant
SN74CBT3245CDGVR	Texas Instruments	8 x 1:1	4.0 ~ 5.5	-40 ~ 85	20-TVSOP	Active	ROHS3 Compliant

Engineering Selection Recommendations

For Direct Package Replacement (20-TSSOP): FST3245MTCX, PI5C3245LE, PI5C3245LEX, and SN74CBT3245APWR provide pin-compatible alternatives. FST3245MTCX maintains onsemi sourcing with improved RoHS3 compliance. SN74CBT3245APWR offers Texas Instruments sourcing with identical electrical specifications.

For Active Product Status: SN74CBT3245CDBQR, SN74CBT3245CDBR, and SN74CBT3245CDGVR are currently active products, ensuring long-term availability and supply chain stability. These parts are suitable for new designs requiring extended product lifecycle support.

For Alternative Package Formats: PI5C3245QEX provides a 20-QSOP package option for designs with different PCB layout constraints. SN74CBT3245ADGVR and SN74CBT3245CDGVR offer 20-TVSOP packaging for applications requiring compact form factors.

For Voltage Range Considerations: Parts from Texas Instruments (SN74CBT series) maintain the full 4V–5.5V supply range. Diodes Incorporated parts (PI5C3245 series) operate within a narrower 4.75V–5.25V range, suitable for regulated 5V supply applications.

Frequently Asked Questions (FAQ)

Q: Can I use PI5C3245LE as a direct replacement for FST3245MTC?

A: Yes, PI5C3245LE is functionally equivalent with identical 8x1:1 bus switch configuration, 20-TSSOP package, and -40°C to 85°C operating range. The voltage supply range is narrower (4.75V–5.25V versus 4V–5.5V), so verify your supply voltage is within this range.

Q: What is the difference between 20-TSSOP and 20-SSOP packages?

A: Both are surface-mount packages with 20 pins. The 20-TSSOP has a width of 0.173" (4.40mm), while 20-SSOP variants range from 0.154" (3.90mm) to 0.209" (5.30mm). PCB footprint compatibility must be verified before substitution.

Q: Are all substitute parts RoHS3 compliant?

A: All listed substitute parts are RoHS3 compliant. The original FST3245MTC does not specify RoHS status, but FST3245MTCX provides the same onsemi base product with confirmed RoHS3 compliance.

Q: Which substitute part has the longest product lifecycle?

A: SN74CBT3245CDBQR, SN74CBT3245CDBR, and SN74CBT3245CDGVR are classified as Active products, indicating current production and extended availability. Last Time Buy parts (PI5C3245 series and other SN74CBT variants) have limited procurement windows.

Q: Can I substitute a 20-QSOP package part in a 20-TSSOP footprint?

A: No. PI5C3245QEX uses a 20-QSOP package with different pin spacing and physical dimensions. PCB layout redesign is required for this substitution.

Q: What is the MSL (Moisture Sensitivity Level) difference between parts?

A: FST3245MTC and most substitutes have MSL 1 (Unlimited), indicating no moisture sensitivity restrictions. SN74CBT3245CDBQR has MSL 2 (1 Year), requiring storage in controlled humidity conditions and baking before reflow if shelf life exceeds one year.

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