74FST3257DR2 Equivalent & Substitute Parts

Part Overview

The 74FST3257DR2 is a Multiplexer/Demultiplexer logic IC with 4 x 2:1 circuit configuration in a 16-SOIC surface mount package. This component operates with single supply voltage between 4V and 5.5V across an operating temperature range of -40°C to 85°C. The 74FST3257DR2 is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement.

Key Parameters

Parameter	Value
Type	Multiplexer/Demultiplexer
Circuit Configuration	4 x 2:1
Independent Circuits	1
Voltage Supply Source	Single Supply
Voltage - Supply Range	4V ~ 5.5V
Operating Temperature	-40°C ~ 85°C
Mounting Type	Surface Mount
Package / Case	16-SOIC (0.154", 3.90mm Width)
Moisture Sensitivity Level (MSL)	1 (Unlimited)

Substitute Part Grouping Explanation

Substitution for the 74FST3257DR2 is determined by the following critical parameters:

Functional equivalence: 4 x 2:1 Multiplexer/Demultiplexer configuration with 1 independent circuit
Electrical compatibility: Single supply voltage operation within 4V to 5.5V range; operating temperature -40°C to 85°C
Physical compatibility: 16-SOIC surface mount package (0.154", 3.90mm width)
Environmental compliance: MSL 1 rating; REACH Unaffected status

Substitute parts are grouped into three categories based on manufacturer and product status:

Direct Manufacturer Equivalents (onsemi): Parts maintaining identical base product specifications with different packaging formats
Cross-Manufacturer Direct Equivalents (Texas Instruments): Parts from alternative manufacturers with identical functional and electrical specifications
Parametric Equivalents (NXP Semiconductors): Parts meeting all electrical and mechanical requirements with compatible pinout and functionality

Parameter Comparison

Part Number	Manufacturer	Series	Circuit	Voltage Supply	Operating Temp	Package	Product Status	RoHS Status
74FST3257DR2	onsemi	74FST	4 x 2:1	4V ~ 5.5V	-40°C ~ 85°C	16-SOIC	Obsolete	RoHS non-compliant
74FST3257DR2G	onsemi	74FST	4 x 2:1	4V ~ 5.5V	-40°C ~ 85°C	16-SOIC	Last Time Buy	ROHS3 Compliant
NLV74FST3257DR2G	onsemi	74FST	4 x 2:1	4V ~ 5.5V	-40°C ~ 85°C	16-SOIC	Obsolete	ROHS3 Compliant
SN74CBT3257CDR	Texas Instruments	74CBT	4 x 2:1	4.5V ~ 5.5V	-40°C ~ 85°C	16-SOIC	Active	ROHS3 Compliant
SN74CBT3257D	Texas Instruments	74CBT	4 x 2:1	4.5V ~ 5.5V	-40°C ~ 85°C	16-SOIC	Last Time Buy	ROHS3 Compliant
SN74CBT3257DR	Texas Instruments	74CBT	4 x 2:1	4.5V ~ 5.5V	-40°C ~ 85°C	16-SOIC	Last Time Buy	ROHS3 Compliant
CBT3257AD,118	NXP Semiconductors	74CBT	4 x 2:1	4.5V ~ 5.5V	-40°C ~ 85°C	16-SOIC	Active	Not specified
SN74CBT3257CD	Texas Instruments	74CBT	4 x 2:1	4.5V ~ 5.5V	-40°C ~ 85°C	16-SOIC	Active	ROHS3 Compliant

Engineering Selection Recommendations

For new designs requiring long-term availability: Select SN74CBT3257CDR, SN74CBT3257CD, or CBT3257AD,118. These parts carry Active product status, ensuring continued manufacturer support and supply chain availability. All three options are ROHS3 compliant and meet the full electrical and mechanical specifications of the 74FST3257DR2.

For legacy system maintenance: The 74FST3257DR2G provides direct compatibility as an onsemi equivalent with Last Time Buy status and ROHS3 compliance. This option maintains the original manufacturer lineage while offering improved environmental compliance compared to the obsolete 74FST3257DR2.

For voltage-sensitive applications: Verify that designs operating at 4V to 4.5V are compatible with Texas Instruments and NXP alternatives, which specify a minimum supply voltage of 4.5V. The onsemi 74FST3257DR2 and 74FST3257DR2G support operation down to 4V.

For compliance-critical applications: All substitute parts except CBT3257AD,118 carry explicit ROHS3 compliance certification. The 74FST3257DR2 is RoHS non-compliant and should be replaced in applications requiring regulatory compliance.

Frequently Asked Questions (FAQ)

Q: Can the 74FST3257DR2 be directly replaced with SN74CBT3257CDR?

A: Yes. Both parts share identical functional specifications (4 x 2:1 Multiplexer/Demultiplexer), electrical parameters (single supply, -40°C to 85°C operation), and 16-SOIC packaging. The SN74CBT3257CDR has Active product status and ROHS3 compliance, making it suitable for new designs and legacy replacements.

Q: What is the difference between 74FST3257DR2 and 74FST3257DR2G?

A: Both are onsemi products with identical electrical and mechanical specifications. The primary differences are product status (Obsolete vs. Last Time Buy) and RoHS compliance (non-compliant vs. ROHS3 compliant). The 74FST3257DR2G is the preferred option for ongoing procurement.

Q: Are there voltage compatibility concerns when substituting with Texas Instruments parts?

A: Texas Instruments SN74CBT3257 series parts specify a minimum supply voltage of 4.5V, compared to 4V for onsemi 74FST3257 parts. Designs operating at 4V to 4.5V must use onsemi equivalents or verify Texas Instruments parts at the lower voltage limit.

Q: What packaging options are available for substitute parts?

A: Substitute parts are available in multiple packaging formats: Tape & Reel (74FST3257DR2G), Cut Tape (NLV74FST3257DR2G, SN74CBT3257CDR, SN74CBT3257DR), Tube (SN74CBT3257D, SN74CBT3257CD), and Bulk (CBT3257AD,118). Select packaging based on procurement volume and assembly requirements.

Q: Is the NLV74FST3257DR2G a suitable replacement despite Obsolete status?

A: The NLV74FST3257DR2G meets all electrical and mechanical requirements and carries ROHS3 compliance. However, its Obsolete status indicates limited future availability. For long-term designs, Active status parts (SN74CBT3257CDR, SN74CBT3257CD, CBT3257AD,118) are preferred.

Q: Do all substitute parts maintain the same pinout as the 74FST3257DR2?

A: Yes. All substitute parts use the 16-SOIC package with identical pin configuration, enabling direct socket replacement without PCB modifications.

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