SN74LS645DW Equivalent & Substitute Parts

Part Overview

The SN74LS645DW is a non-inverting transceiver IC manufactured by Texas Instruments, designed for 8-bit data bus applications with 3-state output capability. This component operates within the 4.75V to 5.25V supply voltage range and is housed in a 20-SOIC surface mount package. The part is currently in Last Time Buy status, indicating end-of-life production. Identifying equivalent and substitute parts is necessary to ensure design continuity and maintain supply chain reliability for ongoing production and maintenance applications.

Key Parameters

Parameter	Value
Manufacturer Part Number	SN74LS645DW
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	4.75V ~ 5.25V
Operating Temperature	0°C ~ 70°C (TA)
Package / Case	20-SOIC (0.295", 7.50mm Width)
Mounting Type	Surface Mount
Product Status	Last Time Buy
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitute parts for the SN74LS645DW are classified based on strict electrical and mechanical compatibility criteria. The primary substitution parameters are:

Logic type: Transceiver, Non-Inverting
Number of elements: 1
Number of bits per element: 8
Output type: 3-State
Supply voltage range: 4.75V ~ 5.25V
Operating temperature range: 0°C ~ 70°C
Package / Case: 20-SOIC (0.295", 7.50mm Width)
Mounting type: Surface Mount

Two substitute parts meet these criteria with variations in output current specifications and product status. The SN74LS645-1DWR is the manufacturer-recommended substitute with identical electrical parameters except for output low current (48mA vs. 24mA). The SN74LS245DW is a parametric equivalent from onsemi with matching output current specifications but different base product number and compliance status.

Parameter Comparison

Parameter	SN74LS645DW (Main)	SN74LS645-1DWR (MFR Recommended)	SN74LS245DW (Parametric Equivalent)
Manufacturer	Texas Instruments	Texas Instruments	onsemi
Logic Type	Transceiver, Non-Inverting	Transceiver, Non-Inverting	Transceiver, Non-Inverting
Number of Elements	1	1	1
Number of Bits per Element	8	8	8
Output Type	3-State	3-State	3-State
Current - Output High, Low	15mA, 24mA	15mA, 48mA	15mA, 24mA
Voltage - Supply	4.75V ~ 5.25V	4.75V ~ 5.25V	4.75V ~ 5.25V
Operating Temperature	0°C ~ 70°C (TA)	0°C ~ 70°C (TA)	0°C ~ 70°C (TA)
Package / Case	20-SOIC (0.295", 7.50mm Width)	20-SOIC (0.295", 7.50mm Width)	20-SOIC (0.295", 7.50mm Width)
Mounting Type	Surface Mount	Surface Mount	Surface Mount
Product Status	Last Time Buy	Active	Obsolete
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	RoHS non-compliant

Engineering Selection Recommendations

The SN74LS645-1DWR is the primary substitute for the SN74LS645DW. Both parts are manufactured by Texas Instruments, share identical electrical specifications with the exception of output low current (48mA vs. 24mA), and maintain ROHS3 compliance. The SN74LS645-1DWR is in Active product status, ensuring long-term availability and supply chain stability. The higher output low current specification of the SN74LS645-1DWR provides enhanced drive capability and is functionally compatible with applications designed for the original part.

The SN74LS245DW from onsemi is a parametric equivalent with matching output current specifications and identical functional parameters. However, this part is classified as Obsolete and does not meet RoHS3 compliance requirements. Selection of the SN74LS245DW should be limited to legacy applications where RoHS compliance is not mandated and long-term availability is not a concern.

For new designs and ongoing production requiring regulatory compliance and supply continuity, the SN74LS645-1DWR is the recommended substitute.

Frequently Asked Questions (FAQ)

Q: Can the SN74LS645-1DWR directly replace the SN74LS645DW in existing designs?

A: Yes. The SN74LS645-1DWR is electrically compatible with the SN74LS645DW. Both parts share identical logic type, element count, bit width, output type, supply voltage range, and operating temperature specifications. The difference in output low current (48mA vs. 24mA) represents enhanced drive capability and does not create compatibility issues in standard applications.

Q: What is the significance of the packaging difference between SN74LS645DW and SN74LS645-1DWR?

A: The SN74LS645DW is supplied in Tube packaging, while the SN74LS645-1DWR is supplied in Tape & Reel (TR) packaging. Both parts use the identical 20-SOIC physical package. The packaging difference affects handling and automated assembly processes but does not impact electrical or mechanical compatibility.

Q: Why is the SN74LS245DW listed as a substitute if it is Obsolete?

A: The SN74LS245DW meets the core electrical and mechanical substitution criteria for the SN74LS645DW, including identical logic type, element count, bit width, output type, supply voltage, operating temperature, and package specifications. However, its Obsolete status and RoHS non-compliance status make it unsuitable for new designs or applications requiring regulatory compliance.

Q: Are there any output current limitations when using the SN74LS645-1DWR as a substitute?

A: The SN74LS645-1DWR provides higher output low current (48mA) compared to the original SN74LS645DW (24mA). This enhanced capability is compatible with all applications designed for the original part and does not introduce limitations.

Q: What compliance certifications apply to each substitute part?

A: The SN74LS645DW and SN74LS645-1DWR are both ROHS3 compliant. The SN74LS245DW is RoHS non-compliant. For applications requiring RoHS compliance, only the SN74LS645DW and SN74LS645-1DWR are suitable.

Request Quote (Ships tomorrow)

Part Number

Quantity

Company

Contact Name

E-mail

Message