Renesas 8745BYILFT Clock Generator IC - Equivalent & Substitute Parts

Part Overview

The Renesas 8745BYILFT is a Clock Generator IC operating at up to 700MHz with integrated PLL and bypass functionality. Designed for 32-LQFP surface mount applications, this component accepts multiple input standards (HCSL, LVDS, LVHSTL, LVPECL, SSTL) and outputs LVDS signals with a 2:5 input-to-output ratio. The product is currently obsolete, necessitating identification of functionally equivalent alternatives for ongoing system support and new designs.

Substiute Parts

8745BYILFT

Renesas Electronics CorporationIn Stock: 9368745BYILFT Datasheet

Current PartRFQ

8T49N242-998NLGI8

Renesas Electronics CorporationIn Stock: 7788T49N242-998NLGI8 Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the 8745BYILFT is determined by the following critical parameters:

• Frequency capability: Substitute must support minimum 700MHz operation
• PLL with Bypass: Required functionality for clock generation and signal conditioning
• Input/Output signal standards: Must accept LVDS and LVPECL inputs; LVDS output capability required
• Supply voltage compatibility: Operating range must overlap with 3.135V – 3.465V
• Operating temperature range: Must support -40°C to +85°C minimum
• Differential signal support: Both input and output must support differential signaling
• Surface mount packaging: Physical form factor must be compatible with existing PCB layouts

The 8T49N242-998NLGI8 qualifies as a substitute based on these parameters, though with functional enhancements and package differences noted in the comparison table below.

Parameter Comparison

Engineering Selection Recommendations

The 8T49N242-998NLGI8 is an active product from Renesas Electronics Corporation and serves as the manufacturer-recommended substitute for the obsolete 8745BYILFT. Key considerations for selection:

Advantages of substitution:

• Active product status ensures long-term availability and supply chain continuity
• ROHS3 compliance meets current environmental and regulatory requirements
• Extended frequency capability (1GHz vs. 700MHz) provides operational margin
• Broader input standard support (includes Crystal input option)
• Lower minimum supply voltage (2.375V) expands application flexibility
• Smaller physical footprint (6x6mm vs. 7x7mm VFQFN package)

Design integration considerations:

• Package change from 32-LQFP to 40-VFQFN requires PCB layout modification
• Increased pin count (40 vs. 32) necessitates routing and placement review
• Input-to-output ratio differs (3:4 vs. 2:5); frequency scaling calculations must be recalculated
• Output multiplier function is not available on substitute; divider-only operation for output scaling
• Functional shift from Clock Generator to Jitter Attenuator may require firmware or configuration adjustments

Frequently Asked Questions (FAQ)

Q: Can the 8T49N242-998NLGI8 directly replace the 8745BYILFT without PCB modifications?

A: No. The substitute uses a different package (40-VFQFN vs. 32-LQFP) with different pinout and physical dimensions. PCB layout redesign is required, including trace routing and component placement adjustments.

Q: What is the functional difference between a Clock Generator and a Jitter Attenuator?

A: The 8745BYILFT generates clock signals with frequency multiplication/division. The 8T49N242-998NLGI8 attenuates jitter from input clock sources while providing frequency division. Both support PLL with bypass operation and accept similar input standards.

Q: Are the supply voltage ranges compatible?

A: The substitute has a wider supply voltage range (2.375V – 3.465V) that fully encompasses the main part's range (3.135V – 3.465V). Existing 3.3V supply designs are compatible without modification.

Q: Does the different input-to-output ratio affect system compatibility?

A: Yes. The 2:5 ratio of the main part differs from the 3:4 ratio of the substitute. Frequency calculations and PLL configuration must be recalculated for the target output frequency. Consult device datasheets for specific ratio programming.

Q: Is the substitute available in the same packaging?

A: No. The 8T49N242-998NLGI8 is available only in 40-VFQFN Exposed Pad packaging. The original 32-LQFP package is not offered for this substitute model.

Q: What are the MSL (Moisture Sensitivity Level) requirements for both parts?

A: Both parts carry MSL-3 rating with a 168-hour floor life. Identical moisture handling and storage procedures apply to both components.

Q: Does the substitute support all input standards of the main part?

A: The substitute supports LVDS, LVHSTL, and LVPECL inputs, matching the main part's common standards. The substitute adds Crystal input capability but does not support HCSL or SSTL inputs. Verify your specific input signal type before substitution.