SY87739LHY - 729MHz Fractional-N Synthesizer | Microchip
料号： SY87739LHY ✓ 量产中SY87739LHY 概述
A fractional-N synthesizer is a phase-locked-loop timing device that derives an output frequency from a stable reference clock using programmable division ratios. The SY87739LHY belongs to the fractional-N synthesizer hierarchy, PLL-based clock generator family, and broader clock and timing IC category. Its protocol-transparent architecture allows a system to synthesize common data-transport reference rates without using a separate dedicated clock generator for every standard.
The primary features include operation from a 3.3V supply, a 27MHz reference input, and output coverage extending to 729MHz. Two tandem PLL circuits provide the frequency synthesis functions: a modified fractional-N stage produces rational-ratio frequencies, while a second integer-ratio stage can adjust the resulting output. Differential PECL outputs are suited to high-speed optical, serial, and telecommunications systems requiring a low-noise clock reference.
The device can generate exact reference frequencies used by common transport protocols, including configurations with or without forward error correction. The first PLL supports protocol rates except those containing FEC or digital-wrapper overhead, while the second PLL provides an additional output adjustment stage. This architecture offers design flexibility while preserving a single-reference-clock implementation, reducing the number of separate oscillator and divider chains required in a communication line card.
Typical applications include Ethernet and Fibre Channel line interfaces, SONET/SDH/ATM transponders, optical communication modules, network timing subsystems, and high-speed serial backplanes. The 729MHz upper limit supports demanding serial links, while the 10MHz lower limit permits synthesis of lower-rate references for adjacent digital circuitry.
PCB implementation should preserve short, impedance-controlled routes for the differential PECL clock outputs and provide a continuous ground reference beneath the exposed pad. Input and output return paths should avoid shared-current coupling with switching supplies. Decoupling capacitors should be placed directly across the device supply pins according to the manufacturer layout guidance, while the exposed pad requires thermal vias and adequate copper area.
This page combines the manufacturer description with package, protocol, frequency, and sourcing details while separating engineering guidance from basic catalog data. It also identifies the verified pin-compatible family options and the unresolved qualification details that should be confirmed before production substitution.
直接替换替代料： SY87739LHY ——相同封装，引脚兼容。需要 PCB 改动的不同封装料号已排除。
本系列中的变体
可与以下型号直接替换的同系列型号： SY87739LHY （相同外形与封装尺寸） ——差异在于 Package, Product Type.
SY87739LHI
✅ 直接替换联系询价
查看数据手册 →SY87739LHY-TR
✅ 直接替换📋 参考替代料（不在目录中）
SY87739LHY 规格参数
| Product Type | Protocol-transparent fractional-N clock synthesizer |
| 电源电压 | 3.3 V |
| Reference Input Frequency | 27 MHz |
| Output Frequency Range | 10 MHz to 729 MHz |
| Maximum Output Frequency | 729 MHz |
| Minimum Output Frequency | 10 MHz |
| 输出配置 | Differential PECL |
| Number of Clock Outputs | 1 output |
| PLL Architecture | 2 tandem PLL stages |
| Synthesis Method | Fractional-N and integer-ratio frequency synthesis |
| Protocol Support | Ethernet, Fibre Channel, SONET, SDH, and ATM reference frequencies |
| FEC Handling | Supported through the second PLL architecture |
| 封装 | 32-pin TQFP with exposed pad, 7 mm x 7 mm |
| 安装类型 | Surface mount |
SY87739LHY 32-pin tqfp with exposed pad, 7 mm x 7 mm 引脚配置指南
SY87739LHY（32-pin tqfp with exposed pad, 7 mm x 7 mm 封装）的引脚配置。 引脚编号、功能和连接图在制造商数据手册中定义。请参阅该手册以了解确切的封装尺寸和焊接指南。
暂无详细引脚数据： SY87739LHY.
请参阅 数据手册 以查看完整引脚配置。
典型应用
SY87739LHY 适用于 6 应用s: Fibre Channel Optical Interfaces, Ethernet Line-Card Clocking, SONET and SDH Transponders, Optical Communication Modules, High-Speed Serial Backplanes, Network Timing Subsystems.
Fibre Channel Optical Interfaces
The SY87739LHY is appropriate for Fibre Channel timing subsystems because its fractional-N architecture generates protocol-relevant reference frequencies from a single 27MHz source and delivers them as differential PECL. The 10MHz-to-729MHz range covers low-rate references through high-speed serial-interface clocks. Two tandem PLL stages provide additional rational-ratio adjustment for rates that cannot be handled by the first stage alone, including configurations affected by FEC or digital-wrapper overhead. This architecture can simplify the clock tree in an optical line card by reducing separate oscillators and divider chains. The design must still be validated against the channel's jitter budget, reference-output amplitude, and propagation requirements.
推荐
Ethernet Line-Card Clocking
The SY87739LHY supports Ethernet line-card clock generation where a single 27MHz reference must support several related data rates. Its protocol-transparent fractional-N method generates rational-ratio clock outputs, and the second PLL stage supplies additional output adjustment where protocol overhead complicates the desired ratio. Differential PECL output is suited to high-speed serializer and transceiver circuitry requiring short, controlled clock links. The synthesizer can reduce board area compared with multiple dedicated oscillator-and-divider chains. Before deployment, verify the exact Ethernet variant, required reference frequency, jitter limit, and whether the transceiver expects PECL or another differential logic standard.
推荐
SONET and SDH Transponders
The SY87739LHY is well suited to SONET, SDH, and ATM transport equipment because the manufacturer identifies these protocols among the frequencies supported by the device. It synthesizes differential PECL clocks up to 729MHz from one 27MHz oscillator, allowing a transponder clock tree to cover both low-rate references and high-speed line rates. The first fractional-N PLL handles rational-ratio generation, while the second P/Q synthesizer extends adjustment for complex protocol cases. This can reduce the number of independent clock sources and simplify synchronization across transmit and receive paths. Final qualification should include jitter, cycle-to-cycle noise, output duty-cycle, and loss-of-reference behavior for the specific transport standard.
推荐
Optical Communication Modules
The SY87739LHY fits optical communication modules requiring a compact, programmable clock source for a high-speed serializer or transceiver. Its differential PECL output reaches 729MHz, while the 10MHz lower limit allows the same device to support slower local references. Deriving multiple related frequencies from one 27MHz source can improve board-area efficiency and reduce clock-distribution complexity in dense optical assemblies. The protocol-transparent fractional-N method is particularly useful where the module must support several data rates or internal divider ratios. Designers should confirm PECL compatibility at the destination device, provide compliant termination, and use short matched routing to limit deterministic jitter.
推荐
High-Speed Serial Backplanes
The SY87739LHY can provide a programmable reference for high-speed serial backplane and data-conversion subsystems that need frequencies derived from a stable 27MHz clock. The wide 10MHz-to-729MHz synthesis range supports both system references and high-speed communication clocks, while differential PECL provides a common interface for many older high-speed logic families. The fractional-N approach offers finer frequency selection than a fixed integer divider and can consolidate multiple clock requirements into one IC. Engineering validation should compare the synthesizer's jitter and spur performance with the complete receiver and transmitter budget. PCB routing also requires controlled differential impedance and a low-impedance return path beneath the clock pair.
推荐
Network Timing Subsystems
The SY87739LHY is useful in network timing subsystems where multiple derived frequencies are required for synchronization, interface, and monitoring blocks. A single 27MHz reference can feed the fractional-N architecture to generate outputs from 10MHz to 729MHz, avoiding several independent oscillators and their associated calibration paths. The protocol-transparent feature allows standard transport frequencies to be produced without a dedicated generator for every rate. Differential PECL outputs suit equipment built around high-speed ECL-family interfaces. The design must account for reference-jitter multiplication, loop filtering, output buffer delay, and synchronization across the clock tree. Environmental and compliance requirements should be confirmed for the finished network equipment.
推荐
推荐产品汇总
工程参考数据： SY87739LHY ——对比、设计指导和合规信息。
选型指南
与替代料对比
| 参数 | 本产品 | SY87739LHI | SY87739LHY-TR |
|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 32-TQFP with exposed pad (7x7 mm) | 32-TQFP with exposed pad (7x7 mm) | 32-TQFP with exposed pad (7x7 mm) |
| Product Type | Protocol-transparent fractional-N clock synthesizer | Fractional-N clock synthesizer | Protocol-transparent fractional-N clock synthesizer |
| Supply Voltage | 3.3 V | 3.3 V | 3.3 V |
| Reference Input | 27 MHz | 27 MHz | 27 MHz |
| Output Frequency Range | 10 MHz to 729 MHz | 10 MHz to 729 MHz | 10 MHz to 729 MHz |
| Output Type | Differential PECL | Differential PECL | Differential PECL |
| Number of Outputs | 1 output | 1 output | 1 output |
| PLL Architecture | 2 tandem PLL stages | 2 tandem PLL stages | 2 tandem PLL stages |
关键差异点
- Broad programmable frequency coverage from one reference （对比 SY87739LHI)
- Direct production packaging alternative （对比 SY87739LHY-TR)
- Two-stage synthesis for complex protocol rates （对比 SY87739LHI)
设计说明
Place the 27MHz reference network and decoupling capacitors close to the relevant SY87739LHY pins, following the manufacturer layout pattern. Route differential PECL outputs as short impedance-controlled pairs with uninterrupted reference planes. Avoid routing clock traces beneath noisy power converters or adjacent to high-current switching nodes because deterministic coupling can increase jitter even when the PLL is operating correctly.
The exposed pad must be connected to ground with multiple thermal vias and continuous copper rather than treated as an unused terminal. Keep thermal-via placement consistent with the manufacturer's footprint while avoiding via stubs on sensitive differential clock traces. Although the synthesizer is not a high-power regulator, reliable pad heat removal helps maintain stable performance across the device's intended operating range.
Use the manufacturer's differential PECL termination and interface recommendations at the receiving device and confirm the board's differential impedance against the actual trace geometry. Keep the reference clock path short and preserve controlled return paths beneath both clock conductors. Validate eye margin, deterministic jitter, and spurious content at the actual receiver because a clean synthesis ratio alone does not guarantee signal integrity.
Do not select a replacement solely because it covers 10MHz to 729MHz. The replacement must also use a 27MHz reference, provide differential PECL at the same pins, share the 32-TQFP exposed-pad footprint, and accept the same programming scheme. For SY87739LHI, confirm temperature grade and qualification; for SY87739LHY-TR, confirm that reel packaging matches the assembly process.
合规信息
No explicit RoHS, REACH, AEC-Q100, lead-free, halogen-free, or conflict-minerals status was identified for this exact MPN. Confirm current declarations with Microchip before production release.
