CDCU877GQLT Clock Driver Equivalent & Substitute Parts

Part Overview

The CDCU877GQLT is a DDR2 memory clock buffer/driver IC manufactured by Texas Instruments, designed for high-speed clock distribution in memory subsystems. This device features a 1:10 input-to-output ratio with differential signaling on both input and output, operating at frequencies up to 400MHz with 1.8V supply voltage compatibility.

The CDCU877GQLT is classified as obsolete. Identifying suitable substitute components is necessary to maintain design continuity and ensure availability for new production runs or system upgrades where this legacy device is no longer procurable.

Substiute Parts

CDCU877GQLT

Texas InstrumentsIn Stock: 1200CDCU877GQLT Datasheet

Current PartRFQ

98ULPA877AHT

Renesas Electronics CorporationIn Stock: 83598ULPA877AHT Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitute components for the CDCU877GQLT must satisfy the following electrical and mechanical criteria:

Primary Substitution Criteria:

• Clock/Timing category with DDR2 memory application focus
• PLL functionality present
• 1:10 input-to-output ratio
• Differential input and output signaling capability
• SSTL-18 or compatible output signal standard
• Supply voltage range: 1.7V ~ 1.9V
• Surface mount packaging with BGA form factor
• Maximum frequency ≥ 400MHz

Secondary Compatibility Factors:

• Package pin count and footprint compatibility
• Operating temperature range (minimum -40°C to +85°C preferred)
• Moisture sensitivity classification
• RoHS and REACH compliance status alignment

The 98ULPA877AHT from Renesas Electronics Corporation meets these substitution criteria as an active product with equivalent functional specifications and compatible electrical parameters.

Parameter Comparison

Engineering Selection Recommendations

The 98ULPA877AHT qualifies as a functional substitute for the obsolete CDCU877GQLT based on matching electrical specifications and active product status. Both devices share identical supply voltage ranges, input-to-output ratios, differential signaling architecture, and DDR2 memory application focus.

Key Considerations:

The 98ULPA877AHT operates at a maximum frequency of 410MHz, which exceeds the CDCU877GQLT specification of 400MHz, providing margin for clock distribution applications. Both devices maintain SSTL-18 output compatibility and equivalent PLL functionality.

Operating temperature range differs between the two devices. The CDCU877GQLT supports -40°C to +85°C, while the 98ULPA877AHT operates from 0°C to +70°C. Applications requiring extended low-temperature operation below 0°C must account for this limitation.

Package form factors differ: the CDCU877GQLT uses 56-VFBGA while the 98ULPA877AHT uses 52-VFBGA. PCB layout modifications are required to accommodate the different pin counts and footprint dimensions.

Moisture sensitivity classification increases from MSL 2 (1 Year) to MSL 3 (168 Hours) with the Renesas device, requiring adjusted storage and handling protocols.

Both devices maintain identical RoHS non-compliant and REACH Unaffected compliance status, ensuring regulatory alignment with legacy system requirements.

Frequently Asked Questions (FAQ)

Q: Can the 98ULPA877AHT directly replace the CDCU877GQLT without PCB modifications?

A: No. The 98ULPA877AHT uses a 52-pin BGA package while the CDCU877GQLT uses a 56-pin BGA package. PCB layout redesign is required to accommodate the different footprint and pin configuration.

Q: What is the frequency margin between these devices?

A: The 98ULPA877AHT operates at 410MHz maximum, compared to 400MHz for the CDCU877GQLT. This 10MHz margin is sufficient for DDR2 clock distribution applications operating at or below 400MHz.

Q: Are there temperature range limitations with the substitute part?

A: Yes. The 98ULPA877AHT operates from 0°C to +70°C, while the CDCU877GQLT supports -40°C to +85°C. Applications requiring operation below 0°C or above 70°C cannot use the Renesas substitute without thermal management modifications or alternative component selection.

Q: How do the moisture sensitivity levels differ?

A: The CDCU877GQLT is classified as MSL 2 with a 1-year shelf life, while the 98ULPA877AHT is MSL 3 with a 168-hour shelf life. The Renesas device requires more stringent moisture control during storage and handling.

Q: Are the input signal specifications compatible?

A: The CDCU877GQLT specifies SSTL-18 input, while the 98ULPA877AHT specifies Clock input. Both devices accept differential clock signals compatible with DDR2 memory subsystems. Verify input impedance and signal integrity requirements for your specific application.

Q: Do both devices support the same supply voltage?

A: Yes. Both the CDCU877GQLT and 98ULPA877AHT operate with supply voltage in the range of 1.7V to 1.9V, ensuring power supply compatibility.

Q: What is the substitution status of the CDCU877GQLT?

A: The CDCU877GQLT is obsolete. The 98ULPA877AHT is an active product from Renesas Electronics Corporation and represents the recommended manufacturer substitute for new designs and production continuity.