MK2745-21S - 80MHz DVD/MPEG Clock Synthesizer | Renesas
MPN： MK2745-21S ✗ 停產MK2745-21S 概覽
A clock synthesizer is a timing-control IC that uses a phase-locked loop to establish an output clock from a stable reference. In the electronics hierarchy, the MK2745-21S is a clock/frequency synthesizer, a clock-and-timing IC, and a power-management-adjacent system-timing component. Its purpose is to distribute related clock signals accurately within a multimedia or consumer-electronics system, reducing the number of separate oscillators and clock-generation circuits required on the printed circuit board.
Key features include an 80 MHz maximum output frequency, an analog PLL architecture, CMOS output logic, and support for either a crystal or external clock input. The 27 MHz reference arrangement is particularly relevant to DVD and MPEG-2 equipment, where several audio and processor-related clocks must share a common reference. According to the Renesas manufacturer datasheet, the device is positioned as a low-cost, low-jitter, high-performance clock synthesizer for these applications.
Technically, the analog PLL multiplies or divides the reference frequency to develop the required output-clock relationships. Because the reference source and generated outputs are phase-related, the part is intended to provide coherent timing across multiple audio and processor domains. The available specifications identify one PLL circuit, clock or crystal input, and a maximum frequency of 80 MHz. Detailed jitter, output-accuracy, voltage, and temperature limits are not available in the supplied verification excerpts and should be confirmed in the manufacturer datasheet before precision-timing design sign-off.
Typical applications include DVD players, MPEG-2-based multimedia systems, set-top equipment, audio processing platforms, and other embedded products requiring a 27 MHz reference and derived clocks. In these systems, the MK2745-21S can replace separate oscillator and divider arrangements where its supported output set and electrical limits satisfy the design. The benefit is centralized clock management, while the tradeoff is dependence on correct reference configuration, output-enable sequencing, board-level return paths, and stable supply voltage.
The primary design consideration is to verify every generated frequency and logic level against the exact system timing tree. Layout should provide a short, clean 27 MHz reference path, a controlled crystal or clock source, and low-impedance ground connections. Decoupling and unused-pin handling must follow the manufacturer datasheet, because incorrect implementation can add reference noise or create unintended clock activity even when the nominal output frequencies are correct.
This page consolidates the verified manufacturer and distributor information, documents missing electrical details without guessing, compares the available same-family Renesas option, and provides application-specific design guidance. It is intended to support component identification, sourcing, and preliminary engineering evaluation while clearly separating confirmed specifications from parameters that still require datasheet review.
直接替換替代品，適用於 MK2745-21S — 相同封裝，腳位對腳位相容。需重新設計 PCB 的不同封裝零件不列入。
MK2745-21SLF
✅ 直接替換聯絡詢價
查看資料表 →MK2745-21S 規格
| Device Type | Clock/Frequency Synthesizer IC |
| Maximum Frequency | 80 MHz |
| PLL | Yes, analog PLL |
| Number of Circuits | 1 PLL circuit |
| Input Type | Clock or crystal |
| Fundamental Reference Frequency | 27 MHz |
| Output Logic | CMOS |
| Input-to-Output Ratio | 2:5 |
| 封裝 | 16-SOIC, 0.154 inch (3.90 mm) width |
| 安裝類型 | Surface mount |
| Supply Voltage Range | 3 V to 5.5 V |
| Differential Input | Not specified |
| Differential Output | Not specified |
MK2745-21S 16-soic, 0.154 inch (3.90 mm) width 腳位配置指南
MK2745-21S（16-soic, 0.154 inch (3.90 mm) width 封裝）的腳位配置。 腳位編號、功能與連接圖定義於製造商資料手冊中。請參閱該手冊以取得確切的封裝尺寸與焊接指引。
無詳細腳位定義資料： MK2745-21S.
請參閱 資料表 以查看完整腳位配置。
典型應用
MK2745-21S 適用於 6 應用s: DVD Player Timing System, MPEG-2 Multimedia Processor Clocks, DVD Audio Clock Distribution, Set-Top Media Processing Platform, Audio-Video Clocking Subsystem, Embedded Consumer Media Processor.
DVD Player Timing System
The MK2745-21S fits a DVD player timing architecture because the Renesas manufacturer datasheet identifies it as a clock synthesizer for DVD systems and accepts a 27 MHz crystal or clock reference. Its analog PLL can generate a coordinated collection of audio, processor, and divided-clock outputs from that reference. This centralizes timing generation and reduces the number of independent oscillator and divider blocks. The 80 MHz maximum output frequency provides headroom for processor-related clocking. Before final schematic release, verify every required frequency, duty cycle, jitter limit, and output-enable state against the full manufacturer datasheet.
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MPEG-2 Multimedia Processor Clocks
The MK2745-21S is suitable for MPEG-2-based multimedia equipment that needs processor and peripheral clocks referenced to a common 27 MHz source. The device accepts either a fundamental-mode crystal or an external clock and uses an analog PLL to derive multiple outputs, including a processor clock and a processor clock divided by two. This relationship is useful when several functional blocks must remain phase-related. The principal engineering benefit is fewer separate timing components, while the tradeoff is that every enabled output must satisfy the device's exact frequency, jitter, and CMOS loading requirements.
推薦
DVD Audio Clock Distribution
The MK2745-21S can support audio-clock generation in a DVD or MPEG-2 system because the Renesas manufacturer datasheet specifically identifies multiple audio output clocks among its synthesized outputs. Operating these clocks from the same 27 MHz reference as the processor timing can simplify the system's master clock arrangement and reduce inter-clock skew risk. The part's CMOS outputs and 80 MHz maximum frequency are confirmed. Exact audio-rate generation, output jitter, duty-cycle limits, and allowable capacitive loading must be verified in the manufacturer datasheet before using the device in a precision audio path.
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Set-Top Media Processing Platform
The MK2745-21S is appropriate for a set-top or media platform that distributes several related clocks from a 27 MHz reference. Its one-PLL architecture, multiple audio and processor outputs, and 16-SOIC surface-mount package provide a compact clock-generation solution for MPEG-2-based equipment. Using one synthesizer can reduce component count and clock-routing complexity compared with multiple discrete sources. The board should provide a short reference path, compliant output loading, and correct sequencing. Jitter and output-accuracy limits are not present in the supplied excerpts and remain design-review items.
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Audio-Video Clocking Subsystem
The MK2745-21S can serve an audio-video subsystem that requires processor, divided-processor, audio, and reference clocks to share a stable source. Its 27 MHz crystal-or-clock input and analog PLL establish the timing relationships, while the confirmed CMOS output type supports conventional digital clock distribution. This can make the subsystem easier to control than independent free-running oscillators. The key performance trade-off is consolidation: designers must verify that no enabled output introduces unacceptable jitter, skew, or edge distortion into the critical audio or video path.
推薦
Embedded Consumer Media Processor
The MK2745-21S fits an embedded consumer-media design that uses a 27 MHz reference and requires multiple derived clocks in a compact surface-mount implementation. The 16-SOIC package is easy to route with conventional PCB techniques, and the device's 80 MHz maximum frequency accommodates processor-related clock outputs described in the manufacturer documentation. Designers should compare its verified output set with the processor's required clock tree before committing to it. Exact supply-current, startup, output-enable, and temperature constraints are not stated in the supplied verification excerpts and must be obtained from the datasheet.
推薦
推薦產品摘要
工程參考資料，適用於 MK2745-21S — 比較、設計指引及合規資訊。
選型指南
與替代品比較
| 參數 | 本產品 | MK2745-21SLF |
|---|---|---|
| Package | 16-SOIC (0.154", 3.90mm Width) | 16-SOIC (0.154", 3.90mm Width) |
| Brand | Renesas Electronics | Renesas Electronics |
| Device Type | Clock/Frequency Synthesizer IC | Clock/Frequency Synthesizer IC |
| Maximum Frequency | 80 MHz | 80 MHz |
| PLL | Yes, analog PLL | Yes |
| Input Type | Clock or crystal | Clock or crystal |
| Output Logic | CMOS | CMOS |
| Supply Voltage Range | 3 V to 5.5 V | 3 V to 5.5 V |
主要差異化特點
- Purpose-built MPEG-2 clock generation (對比MK2745-21SLF)
- Common-reference timing consolidation (對比Discrete oscillator-and-divider implementation)
- Verified 16-SOIC package continuity (對比MK2745-21SLF)
設計說明
Keep the 27 MHz crystal or clock input path short and place any required crystal, load capacitance, and damping network close to the device according to the Renesas datasheet. Provide a continuous ground reference and avoid routing the reference signal adjacent to noisy switching nodes. Because the supplied excerpts confirm a 27 MHz fundamental reference but do not provide the complete reference-network values, use the manufacturer layout and component-selection guidance rather than generic crystal values.
Treat every enabled clock output as a timing signal whose edge quality, loading, and enabled state must be verified against the destination device. The verified output logic is CMOS and the maximum supported frequency is 80 MHz, but the supplied data does not specify rise time, fall time, jitter, or capacitive-load limits. Confirm those parameters in the full datasheet and use short, properly referenced routes for high-frequency processor-related outputs.
The MK2745-21SLF listing confirms a 3 V to 5.5 V supply range for that closely related option, but the supplied excerpts do not provide the MK2745-21S supply-current limits or decoupling values. Place the manufacturer-recommended bypass capacitors at the supply and ground pins, verify startup current, and ensure the source impedance can support the PLL and all enabled outputs. Confirm the exact MK2745-21S voltage and current limits before schematic release.
Do not infer that every clock mentioned for the MK2745-21 family is simultaneously available or enabled in the S orderable variant. The manufacturer description lists multiple audio and processor-related outputs, but the supplied excerpts omit the complete pin and enable tables. Confirm signal names, frequencies, output-enable polarity, unused-pin treatment, and test modes from the official datasheet. A correct package fit alone is insufficient to approve a second-source substitution.
合規資訊
The supplied verified excerpts do not provide explicit RoHS, REACH, AEC-Q100, lead-free, halogen-free, or conflict-minerals statements for MK2745-21S.
