MK2049-45SI - 51.84MHz Dual PLL Clock Synthesizer | Renesas
MPN: MK2049-45SI ✓ ActiveMK2049-45SI Overview
A phase-locked loop is a timing-control circuit that locks an oscillator phase and frequency to a reference signal. Within the clock and timing hierarchy, a PLL clock synthesizer sits above a crystal oscillator and below communications timing systems, converting or distributing reference clocks while reducing phase noise and jitter. The MK2049-45 family provides selectable output frequencies and buffer-mode options for clocking systems that require deterministic low-jitter timing.
The verified source data identifies 14 selectable output frequencies, two buffer-mode selections, a maximum frequency of 51.84 MHz, and operation from an 8 kHz communications-clock input. A 125 MHz high-frequency input is also listed in the comparison data for buffer or jitter-attenuation use. These functions allow one device to address both synthesized communications-clock generation and buffered high-frequency clock distribution.
The first PLL is VCXO based and relies on a pullable crystal to follow input-clock wander while attenuating jitter. The second PLL provides the device's synthesis path, with programmable output selections providing flexibility across multiple communications requirements. The source material also identifies the MK2049-45SI as a clock generator, PLL clock synthesizer with one listed PLL channel and a 1:3 input-to-output ratio in one abbreviated specification source.
Typical uses include communications infrastructure, line-card timing, 8 kHz-locked reference generation, and high-frequency clock buffering. The device is particularly relevant where an 8 kHz communications reference must be converted into one of 14 supported output frequencies. Its 20-pin SOIC package also allows reuse of an existing surface-mount layout when the appropriate pin configuration and electrical limits are confirmed against the manufacturer datasheet.
Designers should verify the selected output frequency, PLL configuration, loop filters, crystal requirements, input-output ratio, and decoupling network against the official datasheet before layout release. The pullable crystal and VCXO topology are central to jitter performance, so incorrect component selection or filtering can undermine the intended phase-noise benefit. Pin assignments and crystal recommendations must be taken directly from the manufacturer documentation rather than inferred from the abbreviated distributor listing.
This product analysis consolidates the verified distributor and manufacturer information, distinguishes the confirmed 8 kHz synthesis mode from the 125 MHz buffer mode, and identifies unresolved datasheet details explicitly. It also provides sourcing context, package-aware candidate references, and practical design cautions that are not apparent from a distributor search result alone.
Drop-in alternatives for MK2049-45SI — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
MK2049-45ASILFTR
✅ Drop-In📋 Reference alternative (not in catalog)
MK2049-45SILFTR
✅ Drop-In📋 Reference alternative (not in catalog)
MK2049-45SILF
✅ Drop-In📋 Reference alternative (not in catalog)
MK2049-45SI Specifications
| Device Type | Dual PLL clock synthesizer and jitter-attenuation device |
| Supply Voltage | 3.3 V |
| Maximum Output Frequency | 51.84 MHz |
| Communications Input Frequency | 8 kHz |
| High-Frequency Input | 125 MHz |
| Input-to-Output Ratio | 1:3 |
| PLL Architecture | Dual PLL |
| First PLL Architecture | VCXO-based with pullable crystal |
| Selectable Output Frequencies | 14 |
| Buffer Mode Selections | 2 |
| Input Signal Type | Clock |
| Output Signal Type | Clock |
| Differential Input | No |
| Differential Output | No |
| Package | 20-pin SOIC, 7.50 mm width |
MK2049-45SI 20-pin soic, 7.50 mm width Pin Configuration Guide
Pin configuration for MK2049-45SI (20-pin soic, 7.50 mm width package). Pin numbering, functions, and connection diagrams are defined in the manufacturer datasheet. Refer to it for the exact footprint and soldering guidelines.
No detailed pinout data available for MK2049-45SI.
Refer to the datasheet for full pin configuration.
Typical Applications
MK2049-45SI is suitable for 6 applications: 8 kHz Communications Clock Generation, High-Frequency Clock Buffering, Line-Card Timing Reference, Jitter-Attenuated Interface Clocking, Instrumentation Clock Distribution, Industrial Synchronization Network.
8 kHz Communications Clock Generation
The MK2049-45SI fits 8 kHz-locked communications timing because the Renesas device supports a communications-clock input of 8 kHz and provides 14 selectable output frequencies up to 51.84 MHz. It is used as a PLL-based clock synthesizer when a system must derive a stable operating reference from a narrow-band communications source rather than relying only on a free-running oscillator. The VCXO-based first PLL can track signal wander while attenuating input jitter, which is valuable when phase variation would otherwise propagate into downstream logic. During implementation, engineers must select the required output from the datasheet frequency table, establish the prescribed loop filter, and confirm the pullable-crystal configuration. The 3.3 V supply and 20-pin SOIC package support compact communications hardware, although the exact output frequency list and jitter limits require confirmation from the manufacturer document.
High-Frequency Clock Buffering
The MK2049-45SI can serve in high-frequency clock distribution when the source data's 125 MHz input condition applies and the selected output remains within the verified 51.84 MHz maximum-output limit. The device's second operating path supports high-frequency clock buffering and jitter attenuation, while two selectable buffer modes provide configuration flexibility. This use is appropriate where a communications subsystem needs a cleaner local clock or a controlled distribution point without introducing another clock-source topology. Designers should distinguish the 125 MHz input capability from the maximum output rating, calculate the required output ratio, and verify loop bandwidth and output jitter in the Renesas datasheet. Decoupling and return-path layout should follow the manufacturer reference circuit so switching noise is not injected into the sensitive timing path.
Line-Card Timing Reference
The MK2049-45SI is appropriate for line-card timing when the board receives an 8 kHz communications reference and needs one of 14 selectable synthesized clocks. By locking its internal oscillator to the incoming signal, the dual-PLL device can distribute a system-specific clock while reducing input wander and jitter. This architecture is useful in compact line cards where multiple logic domains must share a traceable timing source. The 3.3 V operating supply matches many communications platforms, and the 20-pin SOIC package can simplify board-level integration. Implementation should begin with the exact target output and ratio, then follow the datasheet's loop-filter, crystal, decoupling, and output-routing guidance. Timing margin should be checked across voltage and temperature because detailed limits were not included in the supplied source extract.
Jitter-Attenuated Interface Clocking
The MK2049-45SI can provide jitter attenuation for interface clocking when a higher-frequency reference enters the device and a qualified output is required. Its VCXO-based first PLL uses a pullable crystal to track signal wander, while the buffer selections offer additional ways to configure the clock path. This makes the device relevant to communications and test systems where accumulated phase noise from an upstream source could affect timing margins. The verified 51.84 MHz maximum output rating provides a concrete boundary for initial design selection, but engineers must determine whether the desired output is generated or merely buffered. Component selection should also include the specified pullable crystal, correct loop-filter values, and low-noise layout practices verified from the manufacturer reference design.
Instrumentation Clock Distribution
The MK2049-45SI can be considered for instrumentation clock distribution when a laboratory or industrial instrument needs selectable clocks derived from an 8 kHz reference or a buffered high-frequency source. Its dual-PLL architecture allows one IC to combine synthesis and jitter attenuation, reducing the number of separate clock-conditioning stages when those functions match the family's supported modes. The 3.3 V supply is suitable for many mixed-signal and digital instrument boards, while the 20-pin SOIC package supports conventional surface-mount assembly. Because this is a specialized communications clock PLL rather than a general-purpose function generator, the designer must confirm that the desired frequencies, ratios, and jitter targets appear in the output-selection table. Loop stability and measurement-ground separation are especially important in precision instrumentation.
Industrial Synchronization Network
The MK2049-45SI fits industrial synchronization equipment that distributes a common reference clock among multiple subsystems. Locking to an 8 kHz communications input can establish a repeatable system timing source, while the 14 selectable output frequencies allow local logic to use an appropriate derived clock. The 3.3 V device may be especially relevant to compact control, networking, and embedded communication modules where a separate precision oscillator and synthesis chain would add complexity. The 20-pin SOIC footprint supports assembly and inspection, but the broad operating-temperature and lifecycle details must be obtained from official Renesas documentation before industrial deployment. Layout should keep the PLL loop components and crystal connections compact and mechanically stable, and power filtering must preserve the timing integrity that the jitter-attenuation architecture is intended to provide.
Engineering reference data for MK2049-45SI — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | MK2049-45ASILFTR | MK2049-45SILFTR | MK2049-45SILF |
|---|---|---|---|---|
| Brand | Renesas Electronics | Renesas Electronics | Renesas Electronics | Renesas Electronics |
| Package | 20-pin SOIC | 20-pin SOIC | 20-pin SOIC | 20-pin SOIC |
| Device Type | Dual PLL clock synthesizer | PLL clock synthesizer | PLL clock synthesizer | PLL clock synthesizer |
| Supply Voltage | 3.3 V | 3.3 V | 3.3 V | 3.3 V |
| Maximum Output Frequency | 51.84 MHz | 51.84 MHz | 51.84 MHz | 51.84 MHz |
| Communications Input Frequency | 8 kHz | 8 kHz | 8 kHz | 8 kHz |
| Selectable Output Frequencies | 14 | 14 | 14 | 14 |
| Buffer Mode Selections | 2 | 2 | 2 | 2 |
Key Differentiators
- Combines communications-clock synthesis and jitter attenuation (vs Generic single-function clock generators)
- Supports an 8 kHz communications-clock input (vs General-purpose oscillator-only solutions)
- VCXO-based wander tracking (vs Fixed crystal oscillator references)
- Integrated synthesis and buffering in a 20-pin SOIC (vs Discrete oscillator and PLL implementations)
Design Notes
Use the manufacturer reference layout for the pullable crystal, loop-filter network, PLL supply decoupling, and clock outputs. The VCXO-based first PLL tracks signal wander through the crystal, so long crystal traces, nearby switching nodes, and discontinuous ground returns can degrade timing behavior. Keep sensitive timing nets short, provide a continuous ground reference beneath the device, and place decoupling capacitors at the pins specified by the Renesas application guidance.
Do not treat the listed 125 MHz input capability as permission to generate a 125 MHz output; the verified maximum output frequency is 51.84 MHz. Select the output from the 14-entry frequency table, calculate the required PLL ratio, and configure the associated buffer mode before release. A wrong ratio or loop-filter value can lead to unlock, excessive jitter, or timing margins that fail under system load.
Plan a 3.3 V supply that supports the selected PLL mode, output loading, and digital output drive without excessive supply ripple. Place the required bypass capacitors close to their associated pins and keep switching-regulator routing away from the crystal and loop-filter area. Because the device is intended to suppress input jitter, allowing switching noise onto the PLL supply would undermine the timing benefit for which the architecture is selected.
Confirm the 20-pin SOIC pin assignments and exposed thermal requirements from the official datasheet before schematic capture. The supplied search results establish package size but do not provide a verified pin-name list, so board-layout conversion based only on distributor summaries is unsafe. Also check whether the selected order suffix changes temperature grade, packing format, or lead-finish characteristics before releasing a production BOM.
Compliance Information
The supplied verified web data does not state RoHS, REACH, AEC-Q100, lead-free, halogen-free, or conflict-minerals status. No compliance claim has been inferred.
