DM74ALS645AN Equivalent & Substitute Parts

Part Overview

The DM74ALS645AN is a non-inverting transceiver logic integrated circuit manufactured by onsemi, designed for 8-bit bidirectional data transfer with 3-state output capability. This device operates within the 4.5V to 5.5V supply voltage range and is housed in a 20-pin DIP package. The part is currently classified as obsolete, making equivalent and substitute parts necessary for ongoing system maintenance and new design implementations where pin-compatible alternatives are required.

Key Parameters

Parameter	Value
Manufacturer Part Number	DM74ALS645AN
Manufacturer	onsemi
Series	74ALS
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-DIP (0.300", 7.62mm)
Mounting Type	Through Hole
Product Status	Obsolete

Substitute Part Grouping Explanation

Substitute parts for the DM74ALS645AN are qualified based on the following critical parameters that determine functional and mechanical compatibility:

Electrical Parameters:

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

Mechanical Parameters:

Package / Case: 20-DIP (0.300", 7.62mm)
Mounting Type: Through Hole
Supplier Device Package: 20-PDIP

All substitute parts listed maintain identical electrical specifications and package footprint, ensuring direct pin-for-pin replacement capability. The substitutes are sourced from Texas Instruments, a primary manufacturer within the 74ALS logic family, and are classified as active products with current manufacturing support.

Parameter Comparison

Part Number	Manufacturer	Logic Type	Elements / Bits	Output Type	Current (High/Low)	Supply Voltage	Temp Range	Package	Product Status	RoHS Status
DM74ALS645AN	onsemi	Transceiver, Non-Inverting	1 / 8	3-State	15mA, 24mA	4.5V ~ 5.5V	0°C ~ 70°C	20-DIP	Obsolete	Not Specified
SN74ALS1645AN	Texas Instruments	Transceiver, Non-Inverting	1 / 8	3-State	15mA, 16mA	4.5V ~ 5.5V	0°C ~ 70°C	20-DIP	Active	Not Applicable
SN74ALS245A-1N	Texas Instruments	Transceiver, Non-Inverting	1 / 8	3-State	15mA, 24mA	4.5V ~ 5.5V	0°C ~ 70°C	20-DIP	Active	ROHS3 Compliant
SN74ALS245AN	Texas Instruments	Transceiver, Non-Inverting	1 / 8	3-State	15mA, 24mA	4.5V ~ 5.5V	0°C ~ 70°C	20-DIP	Active	ROHS3 Compliant
SN74ALS623AN	Texas Instruments	Transceiver, Non-Inverting	1 / 8	3-State	15mA, 24mA	4.5V ~ 5.5V	0°C ~ 70°C	20-DIP	Active	ROHS3 Compliant
SN74ALS645A-1N	Texas Instruments	Transceiver, Non-Inverting	1 / 8	3-State	15mA, 24mA	4.5V ~ 5.5V	0°C ~ 70°C	20-DIP	Active	ROHS3 Compliant
SN74ALS645AN	Texas Instruments	Transceiver, Non-Inverting	1 / 8	3-State	15mA, 24mA	4.5V ~ 5.5V	0°C ~ 70°C	20-DIP	Active	ROHS3 Compliant

Engineering Selection Recommendations

All listed substitute parts are qualified for direct replacement of the DM74ALS645AN based on electrical and mechanical parameter equivalence. The following factors support selection:

Product Status Consideration: The original DM74ALS645AN is obsolete. All substitute parts from Texas Instruments are classified as active products with ongoing manufacturing support, ensuring long-term availability and supply chain stability.

Compliance and Certification: Five of the six substitute parts (SN74ALS245A-1N, SN74ALS245AN, SN74ALS623AN, SN74ALS645A-1N, and SN74ALS645AN) carry ROHS3 compliance certification, meeting modern environmental and regulatory requirements. The SN74ALS1645AN does not specify RoHS status but maintains full electrical equivalence.

Output Current Specification: The SN74ALS1645AN specifies output low current of 16mA compared to the original 24mA specification. This represents a minor deviation that may require circuit-level evaluation in applications with marginal current budgets. All other substitutes maintain the original 24mA specification.

Inventory Availability: Multiple substitute options provide redundancy in sourcing. SN74ALS245AN and SN74ALS245A-1N offer the highest inventory levels (3840 and 3056 units respectively), supporting both immediate procurement and long-term supply requirements.