SN74ALS645ADW Equivalent & Substitute Parts

Part Overview

The SN74ALS645ADW is a non-inverting transceiver logic IC manufactured by Texas Instruments, designed for 8-bit bidirectional data transfer with 3-state output capability. This device operates within a 4.5V to 5.5V supply voltage range and is housed in a 20-SOIC surface mount package. The SN74ALS645ADW is classified as Last Time Buy, indicating limited future availability. Identifying equivalent and substitute parts is essential for design continuity, supply chain flexibility, and long-term product support.

Key Parameters

Parameter	Value
Manufacturer Part Number	SN74ALS645ADW
Manufacturer	Texas Instruments
Logic Type	Transceiver, Non-Inverting
Number of Elements	1
Number of Bits per Element	8
Output Type	3-State
Current - Output High, Low	15mA, 24mA
Voltage - Supply	4.5V ~ 5.5V
Operating Temperature	0°C ~ 70°C (TA)
Package / Case	20-SOIC (0.295", 7.50mm Width)
Mounting Type	Surface Mount
RoHS Status	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)
Product Status	Last Time Buy

Substitute Part Grouping Explanation

Substitute parts for the SN74ALS645ADW are qualified based on strict parametric equivalence across the following critical criteria:

Electrical Parameters (Must Match):

Logic Type: Transceiver, Non-Inverting
Number of Elements: 1
Number of Bits per Element: 8
Output Type: 3-State
Current - Output High, Low: 15mA, 24mA
Voltage - Supply: 4.5V ~ 5.5V
Operating Temperature: 0°C ~ 70°C (TA)

Mechanical Parameters (Must Match):

Package / Case: 20-SOIC (0.295", 7.50mm Width)
Mounting Type: Surface Mount

Compliance Parameters (Must Match):

RoHS Status: ROHS3 Compliant
Moisture Sensitivity Level (MSL): 1 (Unlimited)

All identified substitute parts meet these criteria. Packaging format (Tube vs. Tape & Reel) and product status (Active vs. Last Time Buy) are secondary considerations that do not affect electrical or mechanical compatibility.

Parameter Comparison

Part Number	Manufacturer	Logic Type	Bits per Element	Output Type	Current (High/Low)	Supply Voltage	Package	Product Status	Packaging Format	Inventory
SN74ALS645ADW	Texas Instruments	Transceiver, Non-Inverting	8	3-State	15mA, 24mA	4.5V ~ 5.5V	20-SOIC	Last Time Buy	Tube	1007 Pcs
SN74ALS645A-1DWR	Texas Instruments	Transceiver, Non-Inverting	8	3-State	15mA, 24mA	4.5V ~ 5.5V	20-SOIC	Active	Tape & Reel (TR)	1106 Pcs
SN74ALS645A-1DW	Texas Instruments	Transceiver, Non-Inverting	8	3-State	15mA, 24mA	4.5V ~ 5.5V	20-SOIC	Last Time Buy	Tube	1193 Pcs
SN74ALS245A-1DW	Texas Instruments	Transceiver, Non-Inverting	8	3-State	15mA, 24mA	4.5V ~ 5.5V	20-SOIC	Last Time Buy	Tube	2400 Pcs
SN74ALS245ADW	Texas Instruments	Transceiver, Non-Inverting	8	3-State	15mA, 24mA	4.5V ~ 5.5V	20-SOIC	Last Time Buy	Tube	2550 Pcs
SN74ALS623ADW	Texas Instruments	Transceiver, Non-Inverting	8	3-State	15mA, 24mA	4.5V ~ 5.5V	20-SOIC	Active	Tube	759 Pcs

Engineering Selection Recommendations

Primary Recommendation: SN74ALS645A-1DWR

The SN74ALS645A-1DWR is the manufacturer-recommended substitute. It maintains full parametric equivalence to the SN74ALS645ADW while offering Active product status, ensuring long-term availability and supply chain stability. The Tape & Reel packaging format is suitable for automated assembly processes. This part is the preferred choice for new designs and production continuity.

Secondary Recommendations: SN74ALS645A-1DW, SN74ALS245A-1DW, SN74ALS245ADW

These parts provide parametric equivalence with identical electrical and mechanical specifications. SN74ALS245A-1DW and SN74ALS245ADW offer higher inventory levels (2400 and 2550 units respectively), providing supply flexibility. All three maintain Last Time Buy status, consistent with the original part.

Alternative Recommendation: SN74ALS623ADW

The SN74ALS623ADW is parametrically equivalent and carries Active product status, supporting long-term availability. Inventory is lower (759 units), making it suitable as a secondary alternative when primary options are constrained.

Frequently Asked Questions (FAQ)

Q: Can I use SN74ALS645A-1DWR as a direct replacement for SN74ALS645ADW?

A: Yes. Both parts are electrically and mechanically identical. The primary difference is packaging format (Tape & Reel vs. Tube) and product status (Active vs. Last Time Buy). The SN74ALS645A-1DWR is the manufacturer-recommended substitute.

Q: What is the difference between Tube and Tape & Reel packaging?

A: Tube packaging is used for manual handling and lower-volume assembly. Tape & Reel packaging is designed for automated pick-and-place equipment in high-volume production. Both formats contain identical components with identical electrical performance.

Q: Are all substitute parts ROHS3 compliant?

A: Yes. All listed substitute parts meet ROHS3 compliance and carry Moisture Sensitivity Level 1 (Unlimited), matching the original SN74ALS645ADW specifications.

Q: Why should I consider parts with Active status over Last Time Buy?

A: Active status indicates ongoing manufacturing and long-term availability. Last Time Buy status signals limited future production. For new designs or long-term production runs, Active status parts (SN74ALS645A-1DWR, SN74ALS623ADW) provide supply security.

Q: Can I mix different substitute parts in the same design?

A: Yes. All substitute parts are parametrically equivalent and can be used interchangeably without circuit modification. However, maintaining consistency within a single production batch is recommended for traceability and quality control.

Q: What is the operating temperature range for all substitute parts?

A: All substitute parts operate within 0°C to 70°C (TA), identical to the original SN74ALS645ADW.

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