849S625BYILF Clock Synthesizer IC Equivalent & Substitute Parts

Part Overview

The 849S625BYILF is a Clock Synthesizer IC manufactured by Renesas Electronics Corporation, designed for high-frequency timing applications requiring up to 625MHz output. This device features integrated Phase-Locked Loop (PLL) with bypass capability, supporting multiple input standards (LVCMOS, LVTTL, Crystal) and differential LVDS/LVPECL outputs. The part is classified as Obsolete, necessitating identification of functionally equivalent alternatives for new designs and production continuity.

Key Parameters

Parameter	849S625BYILF
Manufacturer	Renesas Electronics Corporation
Category	Clock/Timing
Type	Clock Synthesizer
Frequency - Max	625MHz
PLL	Yes with Bypass
Input Standards	LVCMOS, LVTTL, Crystal
Output Standards	LVDS, LVPECL
Number of Circuits	1
Ratio - Input:Output	2:10
Differential Output	Yes
Voltage - Supply	3.135V ~ 3.465V
Operating Temperature	-40°C ~ 85°C
Package / Case	48-LQFP
Mounting Type	Surface Mount
Product Status	Obsolete
RoHS Status	ROHS3 Compliant
MSL Rating	3 (168 Hours)

Substitute Part Grouping Explanation

Substitution of the 849S625BYILF is determined by the following critical parameters:

Functional Requirements:

Clock synthesis capability with integrated PLL and bypass mode
Maximum frequency support of 625MHz or higher
Single circuit configuration
Differential output capability (LVDS/LVPECL compatible)

Electrical Compatibility:

Supply voltage range overlap or compatibility with 3.135V ~ 3.465V
Operating temperature range of -40°C ~ 85°C minimum
Input standard support for LVCMOS, LVTTL, or Crystal sources
Output standard support for LVDS or LVPECL

Physical & Compliance Requirements:

Surface mount packaging
ROHS3 compliance
MSL rating of 3 or better
Similar or smaller package footprint (48-LQFP baseline)

The RC21008A000GND#BB0 qualifies as a substitute based on these criteria: it maintains clock synthesis functionality with PLL, supports higher maximum frequency (650MHz), provides compatible supply voltage options including the 3.135V ~ 3.465V range, maintains the -40°C ~ 85°C operating temperature range, and meets all compliance requirements.

Parameter Comparison

Parameter	849S625BYILF	RC21008A000GND#BB0	Compatibility Notes
Manufacturer	Renesas Electronics Corporation	Renesas Electronics Corporation	Same manufacturer
Category	Clock/Timing	Clock/Timing	Equivalent category
Type	Clock Synthesizer	Clock Generator	Both provide clock synthesis with PLL
Frequency - Max	625MHz	650MHz	Substitute supports higher frequency
PLL	Yes with Bypass	Yes	Both include PLL functionality
Input Standards	LVCMOS, LVTTL, Crystal	CML, HCSL, LVCMOS, LVDS, LVPECL, Crystal	Substitute supports broader input options
Output Standards	LVDS, LVPECL	LP-HCSL, LVCMOS, LVDS	Substitute supports LVDS; verify LVPECL requirement
Number of Circuits	1	1	Equivalent
Differential Output	Yes	Yes	Both support differential outputs
Voltage - Supply	3.135V ~ 3.465V	1.71V ~ 1.89V, 2.375V ~ 2.625V, 3.135V ~ 3.465V	Substitute includes compatible 3.3V range
Operating Temperature	-40°C ~ 85°C	-40°C ~ 85°C	Equivalent
Package / Case	48-LQFP	40-VFQFN Exposed Pad	Different package; PCB layout redesign required
Mounting Type	Surface Mount	Surface Mount	Equivalent
Product Status	Obsolete	Active	Substitute is in active production
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	Equivalent compliance
MSL Rating	3 (168 Hours)	3 (168 Hours)	Equivalent moisture sensitivity

Engineering Selection Recommendations

The RC21008A000GND#BB0 is suitable as a substitute for the obsolete 849S625BYILF based on the following engineering criteria:

Product Status & Availability: The 849S625BYILF is classified as Obsolete, making long-term supply and support unavailable. The RC21008A000GND#BB0 maintains Active product status with current manufacturing support from Renesas Electronics Corporation.

Compliance & Certifications: Both parts maintain ROHS3 compliance and equivalent MSL ratings (3, 168 Hours), ensuring compatibility with modern manufacturing and environmental standards. Both carry EAR99 ECCN classification and REACH Unaffected status.

Functional Equivalence: The substitute provides clock synthesis with integrated PLL, matching the core functionality of the original part. The higher maximum frequency (650MHz vs. 625MHz) provides additional performance headroom for timing-critical applications.

Supply Voltage Compatibility: The RC21008A000GND#BB0 includes the 3.135V ~ 3.465V supply range required by the original design, along with additional voltage options for flexible system integration.

Package Consideration: The substitute uses a 40-VFQFN package versus the original 48-LQFP. This represents a smaller footprint but requires PCB layout redesign and verification of signal integrity for the new pinout configuration.

Frequently Asked Questions (FAQ)

Q: Can the RC21008A000GND#BB0 directly replace the 849S625BYILF without PCB modifications?

A: No. The substitute uses a different package (40-VFQFN vs. 48-LQFP) with a different pinout. PCB layout redesign is required, including trace routing, via placement, and decoupling capacitor repositioning. Schematic review is necessary to verify signal assignments.

Q: What is the key difference between Clock Synthesizer and Clock Generator classifications?

A: Both device types incorporate PLL-based frequency synthesis. The functional distinction in this context is minimal; both parts generate output clocks from input references through multiplication/division ratios. The RC21008A000GND#BB0 provides equivalent synthesis capability.

Q: Does the RC21008A000GND#BB0 support LVPECL output like the original part?

A: The RC21008A000GND#BB0 specifies LP-HCSL, LVCMOS, and LVDS output standards. LVPECL output is not listed in the provided specifications. If LVPECL output is a critical requirement, output signal compatibility must be verified through detailed datasheet review and application circuit analysis.

Q: Are the input/output ratio specifications compatible?

A: The original part specifies a 2:10 input:output ratio. The substitute specifies a 3:8 ratio. These ratios represent different frequency multiplication/division configurations. Application-specific frequency requirements must be verified against the substitute's programmable ratio capabilities.

Q: What is the significance of the Exposed Pad in the 40-VFQFN package?

A: The exposed pad provides thermal and electrical grounding. This design feature improves heat dissipation compared to non-exposed pad packages. PCB layout must include proper thermal via placement and copper area connection to the exposed pad for optimal thermal performance.

Q: Are both parts suitable for the same operating temperature range?

A: Yes. Both parts specify -40°C ~ 85°C operating temperature range, ensuring equivalent thermal performance across industrial and commercial temperature specifications.

Q: What inventory status should be considered for production planning?

A: The original 849S625BYILF shows 2100 pieces in stock but is Obsolete. The RC21008A000GND#BB0 shows 750 pieces in stock with Active product status, indicating ongoing availability and manufacturing support for future production runs.

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