74HCT646D,652 Equivalent & Substitute Parts

Part Overview

The 74HCT646D,652 is a non-inverting transceiver logic integrated circuit manufactured by NXP USA Inc. in the 74HCT series. This device functions as a 1-element, 8-bit transceiver with 3-state output capability, designed for bidirectional data transmission in digital systems. The part is classified as obsolete, making equivalent and substitute parts necessary for ongoing system maintenance, redesign, and procurement planning. Substitute parts must maintain functional equivalence through matching logic type, bit configuration, output characteristics, and package compatibility.

Substiute Parts

74HCT646D,652

NXP USA Inc.In Stock: 92974HCT646D,652 Datasheet

Current PartRFQ

CD74HCT646M96

Harris CorporationIn Stock: 2956CD74HCT646M96 Datasheet

UpgradeRFQ

CD74ACT652M96

Texas InstrumentsIn Stock: 1053CD74ACT652M96 Datasheet

MFR RecommendedRFQ

SN74HCT646DW

Texas InstrumentsIn Stock: 2149SN74HCT646DW Datasheet

MFR RecommendedRFQ

SN74HCT646DWR

Texas InstrumentsIn Stock: 1237SN74HCT646DWR Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution for the 74HCT646D,652 is determined by the following critical parameters:

• Logic Type & Configuration: All substitutes must be non-inverting transceivers with 1 element and 8 bits per element
• Output Characteristics: 3-state output capability is mandatory
• Supply Voltage: 4.5V ~ 5.5V operating range
• Package Compatibility: 24-SOIC surface mount package with 0.295" (7.50mm) width
• Output Current: Substitutes with 6mA output (high/low) maintain direct compatibility; higher current ratings (24mA) provide enhanced drive capability
• Operating Temperature Range: Substitutes must support at minimum -40°C ~ 125°C; extended ranges (-55°C ~ 125°C) offer broader environmental tolerance
• Product Status & Compliance: Active or manufacturer-recommended parts with ROHS3 compliance are preferred for new designs

Parameter Comparison

Engineering Selection Recommendations

Primary Substitute: CD74ACT652M96 (Texas Instruments)

The CD74ACT652M96 is the manufacturer-recommended substitute. It maintains all functional parameters of the 74HCT646D,652 while offering active product status and ROHS3 compliance. The 24mA output current provides enhanced drive capability compared to the original 6mA specification. Operating temperature range extends to -55°C, supporting broader environmental applications. This part is suitable for new designs and long-term procurement strategies.

Secondary Substitute: SN74HCT646DW (Texas Instruments)

The SN74HCT646DW provides direct electrical equivalence with matching 6mA output current and identical supply voltage range. Active product status and ROHS3 compliance ensure regulatory compliance. Operating temperature is limited to -40°C ~ 85°C, which is narrower than the original specification. This part is appropriate for applications within the specified temperature range and offers immediate availability.

Alternative Substitute: CD74HCT646M96 (Harris Corporation)

The CD74HCT646M96 maintains exact electrical equivalence with 6mA output current and extended operating temperature range (-55°C ~ 125°C). However, RoHS non-compliance limits its use in regulated applications. This part is suitable only for legacy systems or applications without environmental compliance requirements.

Discontinued Option: SN74HCT646DWR (Texas Instruments)

The SN74HCT646DWR is discontinued at DiGi Electronics and should not be selected for new procurement. It provides electrical equivalence but offers no advantage over active alternatives.

Frequently Asked Questions (FAQ)

Q: Can the CD74ACT652M96 replace the 74HCT646D,652 in existing designs?

A: Yes. The CD74ACT652M96 maintains functional equivalence through matching logic type, 8-bit configuration, 3-state output, and 24-SOIC package. The higher output current (24mA vs. 6mA) is backward compatible and provides improved drive capability. Verify that the application does not depend on the original -40°C ~ 125°C temperature range, as this part supports -55°C ~ 125°C.

Q: What is the difference between the 74HCT and 74ACT series?

A: Both series are non-inverting transceivers with identical functional configurations. The primary difference is output current: 74HCT provides 6mA, while 74ACT provides 24mA. Both operate at 4.5V ~ 5.5V supply voltage. The 74ACT series is suitable for applications requiring higher drive current.

Q: Are all substitute parts in the same package?

A: Yes. All substitute parts use the 24-SOIC (0.295", 7.50mm Width) surface mount package, ensuring direct PCB compatibility without layout modifications.

Q: Which substitute is best for new product designs?

A: The CD74ACT652M96 is recommended for new designs. It offers active product status, ROHS3 compliance, extended operating temperature range (-55°C ~ 125°C), and higher output current (24mA). This combination ensures long-term availability, regulatory compliance, and enhanced performance margins.

Q: Can I use SN74HCT646DW if my application operates above 85°C?

A: No. The SN74HCT646DW is rated only to 85°C maximum operating temperature. For applications requiring operation to 125°C, use the CD74ACT652M96 or CD74HCT646M96.

Q: What does RoHS compliance mean for component selection?

A: ROHS3 compliance indicates the part meets Restriction of Hazardous Substances regulations, restricting lead and other hazardous materials. For applications subject to environmental or regulatory requirements, select only ROHS3-compliant parts: CD74ACT652M96, SN74HCT646DW, or SN74HCT646DWR. The CD74HCT646M96 is RoHS non-compliant and unsuitable for regulated applications.