PI49FCT3805AHEX Clock Fanout Buffer Equivalent & Substitute Parts

Part Overview

The PI49FCT3805AHEX is a Clock Fanout Buffer (Distribution) IC manufactured by Diodes Incorporated, designed for 1:5 clock distribution at 66 MHz in a 20-SSOP package. This part is classified as obsolete, making equivalent and substitute parts necessary for new designs and ongoing production requirements. The 49FCT series provides CMOS/TTL compatible clock buffering solutions for timing-critical applications requiring signal distribution across multiple endpoints.

Key Parameters

Parameter	PI49FCT3805AHEX
Manufacturer	Diodes Incorporated
Series	49FCT
Type	Fanout Buffer (Distribution)
Number of Circuits	2
Ratio - Input:Output	1:5
Differential Input/Output	No/No
Input Logic	CMOS, TTL
Output Logic	CMOS
Frequency - Max	66 MHz
Voltage Supply	3V ~ 3.6V
Operating Temperature	-40°C ~ 85°C
Package / Case	20-SSOP (0.209", 5.30mm Width)
Mounting Type	Surface Mount
RoHS Status	ROHS3 Compliant
Moisture Sensitivity Level	1 (Unlimited)
Product Status	Obsolete

Substitute Part Grouping Explanation

Substitution for the PI49FCT3805AHEX is determined by the following critical parameters:

Primary Substitution Criteria:

Ratio (Input:Output): Must be 1:5
Number of Circuits: Must be 2
Differential Input/Output: Must be No/No
Package Type: 20-SSOP form factor
Mounting Type: Surface Mount
RoHS Compliance: ROHS3 Compliant
Moisture Sensitivity: MSL 1

Secondary Compatibility Parameters:

Input Logic: CMOS and/or TTL compatibility
Output Logic: CMOS output capability
Voltage Supply Range: 3V ~ 3.6V (primary), 2.3V ~ 2.7V (extended range acceptable)
Operating Temperature: -40°C ~ 85°C (full range), 0°C ~ 70°C (commercial range acceptable)
Frequency: 66 MHz minimum (higher frequencies acceptable for backward compatibility)

Substitute parts are grouped into two categories: direct replacements from Renesas Electronics Corporation (formerly the 49FCT product line manufacturer) and alternative Diodes Incorporated variants with enhanced specifications.

Parameter Comparison

Part Number	Manufacturer	Frequency Max	Voltage Supply	Operating Temp	Package	Input Logic	Output Logic	Product Status
PI49FCT3805AHEX	Diodes Incorporated	66 MHz	3V ~ 3.6V	-40°C ~ 85°C	20-SSOP	CMOS, TTL	CMOS	Obsolete
PI49FCT3805BQEX	Diodes Incorporated	80 MHz	3V ~ 3.6V	-40°C ~ 85°C	20-QSOP	CMOS, TTL	CMOS	Active
49FCT20805PYGI	Renesas Electronics	166 MHz	2.3V ~ 2.7V	-40°C ~ 85°C	20-SSOP	CMOS, LVTTL	CMOS, LVTTL	Active
49FCT20805PYGI8	Renesas Electronics	166 MHz	2.3V ~ 2.7V	-40°C ~ 85°C	20-SSOP	CMOS, LVTTL	CMOS, LVTTL	Active
49FCT3805APYG	Renesas Electronics	Not specified	3V ~ 3.6V	0°C ~ 70°C	20-SSOP	CMOS, LVTTL	CMOS, LVTTL	Active
49FCT3805APYG8	Renesas Electronics	Not specified	3V ~ 3.6V	0°C ~ 70°C	20-SSOP	CMOS, LVTTL	CMOS, LVTTL	Active
49FCT3805APYGI	Renesas Electronics	Not specified	3V ~ 3.6V	-40°C ~ 85°C	20-SSOP	CMOS, LVTTL	CMOS, LVTTL	Active
49FCT3805APYGI8	Renesas Electronics	Not specified	3V ~ 3.6V	-40°C ~ 85°C	20-SSOP	CMOS, LVTTL	CMOS, LVTTL	Active
49FCT3805BPYG	Renesas Electronics	Not specified	3V ~ 3.6V	0°C ~ 70°C	20-SSOP	CMOS, LVTTL	CMOS, LVTTL	Active
49FCT3805BPYG8	Renesas Electronics	Not specified	3V ~ 3.6V	0°C ~ 70°C	20-SSOP	CMOS, LVTTL	CMOS, LVTTL	Active
49FCT3805BPYGI	Renesas Electronics	Not specified	3V ~ 3.6V	-40°C ~ 85°C	20-SSOP	CMOS, LVTTL	CMOS, LVTTL	Active

Engineering Selection Recommendations

Primary Recommendation: 49FCT3805APYGI or 49FCT3805APYGI8

These Renesas Electronics parts maintain the 3V ~ 3.6V supply voltage range of the original PI49FCT3805AHEX and provide full industrial temperature range operation (-40°C ~ 85°C). Both parts are ROHS3 compliant with MSL 1 rating. The 49FCT3805APYGI8 variant offers Tape & Reel packaging for automated assembly, while 49FCT3805APYGI provides Tube packaging. These represent the closest functional equivalents with active product status and established supply availability.

Secondary Recommendation: 49FCT3805BPYGI

For applications with commercial temperature requirements (0°C ~ 70°C), the 49FCT3805BPYGI provides an active alternative with identical supply voltage and package specifications. This part is suitable for non-industrial environments where the reduced temperature range is acceptable.

Alternative for Extended Performance: 49FCT20805PYGI or 49FCT20805PYGI8

These Renesas parts offer significantly higher frequency capability (166 MHz) and support LVTTL logic levels. However, they operate at 2.3V ~ 2.7V supply voltage, requiring voltage regulation modifications in systems designed for 3V ~ 3.6V operation. These parts are appropriate only when system redesign to accommodate lower supply voltage is feasible and higher frequency performance is required.

Not Recommended: PI49FCT3805BQEX

While this Diodes Incorporated part is active and offers 80 MHz operation, it uses a 20-QSOP package (0.154", 3.90mm Width) instead of the 20-SSOP package (0.209", 5.30mm Width) of the original part. This package difference requires PCB redesign and is not a direct mechanical substitute.

Frequently Asked Questions (FAQ)

Q: Can I use 49FCT20805PYGI as a direct replacement for PI49FCT3805AHEX?

A: The 49FCT20805PYGI maintains the same 1:5 fanout ratio, 2-circuit configuration, and 20-SSOP package form factor. However, it operates at 2.3V ~ 2.7V supply voltage compared to the original 3V ~ 3.6V specification. Direct substitution requires system-level voltage regulation changes. The higher 166 MHz frequency is backward compatible with the original 66 MHz requirement.

Q: What is the difference between 49FCT3805APYGI and 49FCT3805APYGI8?

A: Both parts are electrically identical. The primary difference is packaging: 49FCT3805APYGI is supplied in Tube packaging for manual assembly, while 49FCT3805APYGI8 is supplied in Tape & Reel (TR) format for automated pick-and-place assembly. Select based on your manufacturing process requirements.

Q: Why are there variants with different temperature ranges (0°C ~ 70°C vs. -40°C ~ 85°C)?

A: The temperature range designation indicates the operating environment specification. Parts rated -40°C ~ 85°C (industrial grade) are suitable for automotive, industrial, and military applications. Parts rated 0°C ~ 70°C (commercial grade) are appropriate for consumer and office equipment. Select based on your application's environmental requirements.

Q: Are all substitute parts ROHS3 compliant?

A: Yes. All substitute parts listed maintain ROHS3 compliance and MSL 1 (Unlimited) moisture sensitivity rating, matching the original PI49FCT3805AHEX specifications.

Q: Can I use PI49FCT3805BQEX in place of PI49FCT3805AHEX?

A: The PI49FCT3805BQEX is electrically compatible and offers improved 80 MHz performance. However, it uses a 20-QSOP package (0.154" width) instead of the 20-SSOP package (0.209" width) of the original part. This requires PCB layout modification and is not a pin-compatible substitute without redesign.

Q: What input logic compatibility should I verify?

A: The original part accepts CMOS and TTL inputs with CMOS outputs. All Renesas substitute parts support CMOS and LVTTL inputs with CMOS and LVTTL outputs, providing full backward compatibility. LVTTL (Low Voltage TTL) is a subset of TTL logic levels and is compatible with standard TTL inputs.

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