74LCX821WM Equivalent & Substitute Parts

Part Overview

The 74LCX821WM is a single-element D-type flip-flop logic integrated circuit with 10-bit capacity, manufactured by onsemi in a 24-SOIC surface mount package. This device is classified as obsolete, which necessitates identification of active equivalent alternatives for new designs and production continuity. The 74LCX821WM operates across a supply voltage range of 2V to 3.6V with a maximum clock frequency of 150 MHz and tri-state, non-inverted outputs suitable for bus-oriented applications.

Substiute Parts

74LCX821WM

onsemiIn Stock: 123174LCX821WM Datasheet

Current PartRFQ

SN74LVC821ADW

Texas InstrumentsIn Stock: 1593SN74LVC821ADW Datasheet

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SN74LVC821ADWR

Texas InstrumentsIn Stock: 1003SN74LVC821ADWR Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution of the 74LCX821WM is based on strict equivalence of the following electrical and mechanical parameters:

• Package Compatibility: Both substitute parts maintain the identical 24-SOIC (0.295", 7.50mm Width) surface mount package, ensuring direct PCB footprint compatibility.
• Functional Equivalence: All parts are single-element D-type flip-flops with 10-bit capacity, positive edge triggering, and tri-state non-inverted outputs.
• Electrical Performance: Clock frequency (150 MHz), output drive capability (24mA high/low), quiescent current (10 µA), and operating temperature range (-40°C ~ 85°C) are identical across all parts.
• Logic Family Compatibility: The 74LVC series (Texas Instruments) is a direct successor to the 74LCX series, with enhanced voltage range support (1.65V ~ 3.6V vs. 2V ~ 3.6V) and improved propagation delay characteristics.
• Supply Voltage Overlap: The 74LVC821 variants operate within the full range of the 74LCX821WM, with extended lower voltage capability.

Parameter Comparison

Engineering Selection Recommendations

The SN74LVC821ADW and SN74LVC821ADWR are direct functional equivalents of the 74LCX821WM with the following engineering considerations:

Product Status: Both Texas Instruments alternatives are classified as active products, ensuring long-term availability and manufacturing support compared to the obsolete 74LCX821WM.

Regulatory Compliance: The SN74LVC821 variants are ROHS3 compliant, meeting current environmental and hazardous substance restrictions. Both parts maintain REACH Unaffected status and identical ECCN/HTSUS classifications.

Electrical Performance: The 74LVC series exhibits marginally higher propagation delay (7.3ns vs. 7ns at 3.3V, 50pF) and lower input capacitance (5pF vs. 7pF), both within acceptable tolerance for standard logic applications. The extended supply voltage range (1.65V minimum vs. 2V) provides additional design flexibility.

Packaging Selection: SN74LVC821ADW is supplied in tube packaging for manual assembly and prototyping. SN74LVC821ADWR is supplied in tape and reel format for automated production environments. Both maintain identical electrical specifications and 24-SOIC package geometry.

Frequently Asked Questions (FAQ)

Q: Can the SN74LVC821ADW or SN74LVC821ADWR be used as direct replacements for the 74LCX821WM?

A: Yes. Both Texas Instruments parts are direct functional and pin-compatible replacements. The 24-SOIC package footprint is identical, and all electrical parameters (clock frequency, output drive, operating temperature, supply voltage overlap) are equivalent or superior.

Q: What is the difference between SN74LVC821ADW and SN74LVC821ADWR?

A: Both parts are electrically identical. The difference is packaging format: SN74LVC821ADW is supplied in tube packaging, while SN74LVC821ADWR is supplied in tape and reel format. Selection depends on assembly method (manual vs. automated).

Q: Are there any timing differences between the 74LCX821WM and the 74LVC821 variants?

A: The 74LVC821 variants exhibit a maximum propagation delay of 7.3ns compared to 7ns for the 74LCX821WM at 3.3V with 50pF load. This 0.3ns difference is negligible for most applications operating at 150 MHz or below.

Q: Does the extended voltage range of the 74LVC821 (1.65V ~ 3.6V) affect compatibility?

A: No. The 74LVC821 operates across the full voltage range of the 74LCX821WM (2V ~ 3.6V) and extends capability to lower voltages. Designs using 2V ~ 3.6V supply will function identically with either part.

Q: What is the significance of the lower input capacitance in the 74LVC821?

A: The 74LVC821 has 5pF input capacitance compared to 7pF for the 74LCX821WM. Lower input capacitance reduces loading on driving circuits and can improve signal integrity in high-speed applications, providing a minor performance advantage.

Q: Are the 74LVC821 parts suitable for new production designs?

A: Yes. Both SN74LVC821ADW and SN74LVC821ADWR are active products with full manufacturing support, ROHS3 compliance, and established supply chains, making them appropriate for new designs and long-term production.