CDCU877ZQLR Equivalent & Substitute Parts

Part Overview

The CDCU877ZQLR is a Memory DDR2 Clock Buffer/Driver IC manufactured by Texas Instruments, designed for high-speed clock distribution in DDR2 memory applications. 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 CDCU877ZQLR is classified as obsolete. Identifying suitable substitute parts is necessary to maintain design continuity and ensure availability for new production runs, system upgrades, or replacement inventory requirements.

Substiute Parts

CDCU877ZQLR

Texas InstrumentsIn Stock: 16725CDCU877ZQLR Datasheet

Current PartRFQ

98ULPA877AHT

Renesas Electronics CorporationIn Stock: 83598ULPA877AHT Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the CDCU877ZQLR must satisfy the following critical parameters to ensure functional and mechanical compatibility:

Mandatory Matching Parameters:

• Package type: 52-VFBGA (52-pin Very Fine Ball Grid Array)
• Mounting type: Surface Mount
• Functional category: Memory DDR2 Clock Buffer/Driver with Multiplexer capability
• Input-to-output ratio: 1:10
• Differential signaling: Yes on both input and output
• Supply voltage range: 1.7V ~ 1.9V (1.8V nominal)
• Output signal type: SSTL-18

Allowable Parameter Variations:

• Maximum frequency: Equal to or greater than 400MHz
• Operating temperature range: May be narrower than the original specification
• Product status: Active or Obsolete (availability dependent)
• RoHS and MSL compliance: May differ based on manufacturing date and regional requirements

The 98ULPA877AHT from Renesas Electronics Corporation qualifies as a substitute based on these criteria.

Parameter Comparison

Engineering Selection Recommendations

Availability Consideration: The CDCU877ZQLR is obsolete and no longer manufactured by Texas Instruments. The 98ULPA877AHT is an active product from Renesas Electronics Corporation with current production inventory, making it the primary substitute option for new designs or replacement stock requirements.

Compliance Considerations: The original CDCU877ZQLR is ROHS3 compliant. The 98ULPA877AHT is RoHS non-compliant. Organizations subject to RoHS regulations must evaluate whether this substitution aligns with procurement and environmental compliance policies.

Operating Temperature Range: The CDCU877ZQLR operates across -40°C to 85°C, while the 98ULPA877AHT operates across 0°C to 70°C. Applications requiring extended low-temperature operation below 0°C or high-temperature operation above 70°C cannot use the Renesas substitute without design modification or thermal management review.

Moisture Sensitivity: The CDCU877ZQLR has MSL 2 (1 Year shelf life), while the 98ULPA877AHT has MSL 3 (168 Hours shelf life). The substitute requires more stringent moisture control during storage and handling. Procurement and assembly processes must accommodate the shorter bake-out window.

Frequency Performance: The 98ULPA877AHT operates at 410MHz maximum, exceeding the 400MHz specification of the CDCU877ZQLR. This performance margin provides additional headroom for clock distribution applications.

Frequently Asked Questions (FAQ)

Q: Can the 98ULPA877AHT be used as a direct replacement for the CDCU877ZQLR in existing designs?

A: The 98ULPA877AHT is functionally compatible at the circuit level, sharing identical package footprint (52-VFBGA), supply voltage (1.7V ~ 1.9V), input-to-output ratio (1:10), and differential signaling characteristics. However, three factors require evaluation: (1) operating temperature range is narrower (0°C to 70°C versus -40°C to 85°C), (2) RoHS compliance differs, and (3) moisture sensitivity level is higher (MSL 3 versus MSL 2). Designs operating within 0°C to 70°C and compatible with RoHS non-compliant components can use this substitute without circuit modification.

Q: What is the difference between the MICROSTAR JUNIOR and CABGA package designations?

A: Both designations refer to 52-pin ball grid array packages with equivalent footprints (7x4.5mm and 4.5x7.0mm are the same physical dimensions, rotated). The MICROSTAR JUNIOR is Texas Instruments' package designation, while CABGA is Renesas Electronics' designation. The physical layout, ball pitch, and PCB footprint are compatible.

Q: Are there any signal integrity differences between these two clock drivers?

A: Both devices support SSTL-18 input and output signaling with differential pairs on both sides. The 98ULPA877AHT includes zero-delay buffer functionality, which may provide improved timing characteristics compared to the CDCU877ZQLR. Timing specifications should be reviewed against application requirements.

Q: What handling precautions apply to the 98ULPA877AHT due to its higher MSL rating?

A: MSL 3 (168 Hours) requires that the component be baked at 125°C for 24 hours if exposed to moisture for more than 168 hours before assembly. The CDCU877ZQLR with MSL 2 (1 Year) allows longer shelf life without baking. Assembly facilities must implement moisture control procedures and track component exposure time accordingly.

Q: Is the 410MHz maximum frequency of the 98ULPA877AHT sufficient for DDR2 applications designed for 400MHz?

A: Yes. The 410MHz specification exceeds the 400MHz requirement, providing a 2.5% performance margin. This additional headroom is acceptable for DDR2 clock distribution applications.

Q: What is the REACH status for both parts?

A: Both the CDCU877ZQLR and 98ULPA877AHT are listed as REACH Unaffected, indicating they are not subject to REACH substance restrictions.