Renesas Electronics 251PMLF Clock/Frequency Synthesizer Equivalent & Substitute Parts

Part Overview

The Renesas Electronics 251PMLF is a Clock/Frequency Synthesizer with Spread Spectrum Clock Generator functionality, rated for 200MHz maximum frequency operation. This 8-SOIC surface mount device features integrated PLL capability with clock and crystal input options, delivering CMOS output signals. The device operates within a 3.15V to 3.45V supply voltage range and is specified for 0°C to 70°C operating temperature.

The 251PMLF carries an Obsolete product status. Identifying equivalent substitute parts is necessary to maintain design continuity, ensure supply chain availability, and support ongoing production requirements for legacy systems utilizing this component.

Substiute Parts

251PMLF

Renesas Electronics CorporationIn Stock: 892251PMLF Datasheet

Current PartRFQ

5L35021B-000NDGI

Renesas Electronics CorporationIn Stock: 7635L35021B-000NDGI Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the 251PMLF are identified based on functional equivalence within the Clock/Timing category. The primary substitution criteria are:

• PLL Capability: Both main and substitute parts must include integrated Phase-Locked Loop functionality
• Input Flexibility: Clock and crystal input support required for design compatibility
• Output Signal Type: CMOS or compatible output standards (LP-HCSL, LVCMOS acceptable as functional equivalents)
• Frequency Range: Substitute maximum frequency must meet or exceed the 200MHz requirement
• Surface Mount Packaging: Continuation of surface mount technology for PCB integration
• Supply Voltage Compatibility: Operating voltage ranges must support system power distribution requirements
• Regulatory Compliance: RoHS and REACH compliance maintained across substitutes

The Renesas Electronics 5L35021B-000NDGI qualifies as a manufacturer-recommended substitute based on these criteria, despite differences in package form factor and expanded operating temperature range.

Parameter Comparison

Engineering Selection Recommendations

The 5L35021B-000NDGI is designated as the manufacturer-recommended substitute for the obsolete 251PMLF. Selection of this substitute is supported by the following engineering factors:

Product Availability: The 251PMLF carries Obsolete status with limited inventory (788 pcs). The 5L35021B-000NDGI maintains Active product status with current manufacturing support (726 pcs in stock), ensuring long-term supply chain viability.

Functional Equivalence: Both devices provide PLL-based clock generation with clock and crystal input support. The substitute's 250MHz maximum frequency exceeds the 251PMLF's 200MHz specification, providing operational headroom for existing designs.

Regulatory Compliance: Both parts maintain ROHS3 compliance and REACH Unaffected status, satisfying environmental and regulatory requirements for industrial and commercial applications.

Design Integration Considerations: The substitute operates at lower supply voltage (1.71V ~ 1.89V versus 3.15V ~ 3.45V) and features expanded operating temperature range (-40°C ~ 85°C versus 0°C ~ 70°C). These differences require circuit-level evaluation for power distribution and thermal management compatibility.

Package Transition: The substitute transitions from 8-SOIC to 20-VFQFN form factor. PCB layout redesign is necessary to accommodate the different pin count (8 versus 20) and package footprint.

Frequently Asked Questions (FAQ)

Q: Can the 5L35021B-000NDGI directly replace the 251PMLF without PCB modification?

A: No. The substitute requires PCB redesign due to package form factor change (8-SOIC to 20-VFQFN), different pin count, and modified supply voltage requirements. Schematic and layout updates are mandatory.

Q: What are the key functional differences between these parts?

A: Both devices provide PLL-based clock generation with clock and crystal inputs. The 5L35021B-000NDGI offers higher maximum frequency (250MHz versus 200MHz), lower supply voltage operation (1.71V ~ 1.89V versus 3.15V ~ 3.45V), and expanded temperature range (-40°C ~ 85°C versus 0°C ~ 70°C). Output signal types differ: the main part provides CMOS output, while the substitute provides LP-HCSL and LVCMOS outputs.

Q: Is the substitute suitable for legacy system designs originally specified for the 251PMLF?

A: The substitute provides functional clock generation capability equivalent to the main part. However, design compatibility requires verification of output signal type compatibility, supply voltage availability in the target system, and thermal operating range requirements. PCB redesign is necessary.

Q: What compliance certifications apply to both parts?

A: Both the 251PMLF and 5L35021B-000NDGI maintain ROHS3 compliance and REACH Unaffected status. Both are classified under ECCN EAR99 and HTSUS 8542.39.0001.

Q: Are there inventory considerations for selecting the substitute?

A: The 251PMLF (Obsolete) has 788 pcs available. The 5L35021B-000NDGI (Active) has 726 pcs in stock with ongoing manufacturing support, providing superior long-term supply chain security for production requirements.