MK3805RI Clock Fanout Buffer IC Equivalent & Substitute Parts

Part Overview

The MK3805RI is a Clock Fanout Buffer (Distribution) IC manufactured by Renesas Electronics Corporation, designed for 1:5 clock distribution at 100 MHz with LVCMOS input/output in a 20-SSOP (0.154", 3.90mm Width) package. This part is classified as obsolete, making equivalent and substitute parts necessary for new designs and ongoing production requirements. The substitute parts listed maintain functional compatibility through equivalent circuit topology, package form factor, and electrical performance parameters.

Substiute Parts

MK3805RI

Renesas Electronics CorporationIn Stock: 758MK3805RI Datasheet

Current PartRFQ

PI49FCT32805QE

Diodes IncorporatedIn Stock: 3967PI49FCT32805QE Datasheet

MFR RecommendedRFQ

PI49FCT32805QEX

Diodes IncorporatedIn Stock: 21168PI49FCT32805QEX Datasheet

MFR RecommendedRFQ

PI49FCT3805BQE

Diodes IncorporatedIn Stock: 1534PI49FCT3805BQE Datasheet

MFR RecommendedRFQ

PI49FCT3805CHE

Diodes IncorporatedIn Stock: 4494PI49FCT3805CHE Datasheet

MFR RecommendedRFQ

PI49FCT3805CQE

Diodes IncorporatedIn Stock: 1571PI49FCT3805CQE Datasheet

MFR RecommendedRFQ

PI49FCT3805DQE

Diodes IncorporatedIn Stock: 4357PI49FCT3805DQE Datasheet

MFR RecommendedRFQ

PI49FCT3805DQEX

Diodes IncorporatedIn Stock: 18360PI49FCT3805DQEX Datasheet

MFR RecommendedRFQ

PI49FCT3805QE

Diodes IncorporatedIn Stock: 1319PI49FCT3805QE Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution for the MK3805RI is determined by the following critical parameters: 1:5 input-to-output ratio, fanout buffer topology with 2 circuits, CMOS-compatible logic levels, 20-SSOP package form factor, surface mount technology, and operating temperature range of -40°C to 85°C. All substitute parts maintain these core functional requirements. Frequency capability, supply voltage range, and compliance status vary among substitutes and determine suitability for specific applications. Substitutes are grouped by frequency rating (50 MHz, 80 MHz, 100 MHz, and 133 MHz) and packaging format (Tube or Tape & Reel).

Parameter Comparison

Engineering Selection Recommendations

For applications requiring direct functional replacement of the MK3805RI at 100 MHz operation, PI49FCT3805CQE provides equivalent frequency performance with identical 20-SSOP (0.154", 3.90mm) package geometry and active product status. This part is ROHS3 compliant, addressing regulatory requirements that the original obsolete part does not meet.

For designs tolerating higher frequency capability, PI49FCT3805DQE and PI49FCT3805DQEX offer 133 MHz operation in the same package footprint with active status and full RoHS compliance. The DQEX variant is supplied in Tape & Reel format for high-volume production environments.

For applications with lower frequency requirements, PI49FCT3805BQE (80 MHz) and PI49FCT3805QE (50 MHz) provide cost-effective alternatives with identical package compatibility and active product status.

PI49FCT3805CHE operates at 100 MHz but uses a wider 20-SSOP package (0.209", 5.30mm). This variant is suitable only for designs where PCB layout accommodates the larger package footprint.

PI49FCT32805QE and PI49FCT32805QEX are 133 MHz alternatives with extended supply voltage range (2.97V ~ 3.63V) and CMOS-only input specification. These parts are appropriate for systems with tighter voltage tolerance requirements.

All substitute parts maintain the 1:5 fanout buffer topology, 2-circuit configuration, and -40°C to 85°C operating temperature range of the original part.

Frequently Asked Questions (FAQ)

Q: Can PI49FCT3805CQE directly replace MK3805RI in existing designs?

A: Yes. PI49FCT3805CQE maintains identical 100 MHz frequency, 1:5 fanout ratio, 2-circuit topology, and 20-SSOP (0.154", 3.90mm) package footprint. Supply voltage range differs slightly (3V ~ 3.6V vs. 3.13V ~ 3.46V), but the substitute range encompasses the original specification. ROHS3 compliance is an improvement over the non-compliant original part.

Q: What is the difference between PI49FCT3805DQEX and PI49FCT3805DQE?

A: Both parts are electrically identical with 133 MHz frequency capability. The primary difference is packaging format: DQEX is supplied in Tape & Reel (TR) format for automated assembly, while DQE is supplied in Tube format for manual handling. Select based on production volume and assembly process requirements.

Q: Why does PI49FCT3805CHE have a different package width?

A: PI49FCT3805CHE uses a 20-SSOP package with 0.209" (5.30mm) width, compared to the standard 0.154" (3.90mm) width of other substitutes. This wider package is physically incompatible with PCB layouts designed for the narrower footprint. Use only if your design accommodates the larger package dimensions.

Q: Can I use PI49FCT32805QE instead of PI49FCT3805DQE?

A: Both operate at 133 MHz with identical package footprint. PI49FCT32805QE has extended supply voltage range (2.97V ~ 3.63V) and CMOS-only input specification, while PI49FCT3805DQE accepts CMOS and TTL inputs with 3V ~ 3.6V supply range. Select PI49FCT32805QE only if your system requires the extended voltage tolerance and does not require TTL input compatibility.

Q: Is the MK3805RI still available for purchase?

A: The MK3805RI is classified as obsolete. Substitute parts from Diodes Incorporated (PI49FCT series) are actively manufactured and available in production quantities. Migration to an active substitute part is recommended for new designs and long-term supply security.

Q: What are the key parameters that determine substitution compatibility?

A: Substitution is determined by: 1:5 input-to-output ratio, fanout buffer topology with 2 circuits, CMOS logic compatibility, 20-SSOP package form factor, surface mount technology, and -40°C to 85°C operating temperature range. Frequency capability and supply voltage range may vary among substitutes based on application requirements.