ICS551MI Clock Fanout Buffer Equivalent & Substitute Parts

Part Overview

The ICS551MI is a Clock Fanout Buffer (Distribution) IC manufactured by Renesas Electronics Corporation, designed for 1:4 clock distribution at frequencies up to 160 MHz in 8-SOIC surface mount packaging. This part is classified as Obsolete, making equivalent and substitute parts necessary for new designs and ongoing production requirements. The ICS551MI operates across a 3V to 5.5V supply range with CMOS input and output logic levels, suitable for general-purpose clock distribution applications in digital systems.

Key Parameters

Parameter	Value
Type	Fanout Buffer (Distribution)
Ratio - Input:Output	1:4
Frequency - Max	160 MHz
Voltage - Supply	3V ~ 5.5V
Input Logic	CMOS
Output Logic	CMOS
Operating Temperature	-40°C ~ 85°C
Package / Case	8-SOIC (0.154", 3.90mm Width)
Mounting Type	Surface Mount
Moisture Sensitivity Level (MSL)	1 (Unlimited)

Substitute Part Grouping Explanation

Substitution for the ICS551MI is determined by strict adherence to the following electrical and mechanical parameters:

Critical Substitution Parameters:

1:4 fanout ratio (input to output configuration)
8-SOIC surface mount package with 0.154" (3.90mm) width
Operating temperature range of -40°C to 85°C
Moisture Sensitivity Level 1 (Unlimited)
CMOS or compatible logic input/output (LVCMOS, LVTTL acceptable)

Frequency Consideration: Substitute parts with maximum frequency ratings of 160 MHz or higher are functionally compatible. The ICS551MI operates at 160 MHz maximum; substitutes rated for 180 MHz provide equivalent or superior performance within the same application envelope.

Supply Voltage Consideration: The ICS551MI operates at 3V to 5.5V. Substitute parts must support this voltage range. Parts with narrower ranges (such as 1.4V to 2.7V) are not direct substitutes due to incompatible supply voltage requirements.

Parameter Comparison

Parameter	ICS551MI	551MILF	NB3N551DG	NB3N551DR2G	PI6C10804WE
Manufacturer	Renesas	Renesas	onsemi	onsemi	Diodes Inc.
Product Status	Obsolete	Active	Active	Active	Discontinued at DiGi Electronics
Type	Fanout Buffer	Fanout Buffer	Fanout Buffer	Fanout Buffer	Fanout Buffer
Ratio - Input:Output	1:4	1:4	1:4	1:4	1:4
Frequency - Max	160 MHz	160 MHz	180 MHz	180 MHz	180 MHz
Voltage - Supply	3V ~ 5.5V	3V ~ 5.5V	3V ~ 5.5V	3V ~ 5.5V	1.4V ~ 2.7V
Input Logic	CMOS	CMOS	LVCMOS, LVTTL	LVCMOS, LVTTL	LVCMOS, LVTTL
Output Logic	CMOS	CMOS	LVCMOS, LVTTL	LVCMOS, LVTTL	LVCMOS, LVTTL
Operating Temperature	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 85°C
Package / Case	8-SOIC	8-SOIC	8-SOIC	8-SOIC	8-SOIC
Packaging Type	-	Tube	Tube	Tape & Reel	Tube
RoHS Status	Non-compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
MSL	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)

Engineering Selection Recommendations

Primary Substitute: 551MILF (Renesas Electronics)

The 551MILF is the direct equivalent to the ICS551MI, maintaining identical electrical specifications (160 MHz maximum frequency, 3V to 5.5V supply, CMOS logic) and package configuration. This part is Active status and ROHS3 compliant, making it the preferred choice for designs requiring exact functional replacement. The 551MILF is available in Tube packaging with 1606 units in stock.

Secondary Substitutes: NB3N551DG and NB3N551DR2G (onsemi)

Both onsemi parts (NB3N551DG in Tube and NB3N551DR2G in Tape & Reel) are functionally compatible substitutes with enhanced specifications. These parts operate at 180 MHz maximum frequency (20 MHz higher than the ICS551MI), support LVCMOS and LVTTL logic levels, and maintain the same 3V to 5.5V supply voltage range and 8-SOIC package. Both are Active status and ROHS3 compliant. The choice between tube and tape & reel packaging depends on production volume and assembly requirements.

Not Recommended: PI6C10804WE (Diodes Incorporated)

The PI6C10804WE does not meet substitution criteria due to incompatible supply voltage specification (1.4V to 2.7V versus the required 3V to 5.5V). Although this part shares the 1:4 fanout ratio, 180 MHz frequency, and 8-SOIC package, the voltage incompatibility makes it unsuitable for direct replacement in applications designed for the ICS551MI. Additionally, this part is Discontinued at DiGi Electronics.

Frequently Asked Questions (FAQ)

Q: Can the 551MILF directly replace the ICS551MI in existing designs?

A: Yes. The 551MILF is electrically and mechanically identical to the ICS551MI, with matching 160 MHz frequency, 3V to 5.5V supply voltage, CMOS logic levels, and 8-SOIC package. The primary difference is product status (Active versus Obsolete) and RoHS compliance (ROHS3 Compliant versus Non-compliant).

Q: What is the advantage of using NB3N551DG or NB3N551DR2G over the 551MILF?

A: The onsemi parts offer 180 MHz maximum frequency compared to 160 MHz, providing 12.5% higher frequency margin. Both support LVCMOS and LVTTL logic levels in addition to CMOS, offering broader logic compatibility. All three parts are functionally compatible for the ICS551MI application.

Q: Why is the PI6C10804WE not suitable as a substitute?

A: The PI6C10804WE operates at 1.4V to 2.7V supply voltage, which does not overlap with the ICS551MI requirement of 3V to 5.5V. This voltage incompatibility prevents direct substitution regardless of matching package and frequency specifications.

Q: Does packaging type (Tube versus Tape & Reel) affect electrical performance?

A: No. Packaging type (Tube or Tape & Reel) affects only handling, storage, and assembly processes. Electrical and thermal performance are identical. Selection depends on production volume, automated assembly capability, and supply chain requirements.

Q: Are all substitute parts RoHS compliant?

A: The 551MILF, NB3N551DG, and NB3N551DR2G are all ROHS3 compliant. The original ICS551MI is RoHS non-compliant. If RoHS compliance is a design requirement, any of the three substitute parts satisfy this criterion.

Q: What is the Moisture Sensitivity Level (MSL) for substitute parts?

A: All substitute parts, like the ICS551MI, have MSL 1 (Unlimited), indicating no moisture sensitivity restrictions for storage or handling.

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