SY87729LHY - 365MHz Fractional-N Clock Synthesizer | Microchip
MPN: SY87729LHY ✓ Hoạt độngSY87729LHY Tóm tắt
A fractional-N synthesizer is a clock and timing IC that synthesizes programmable frequencies from a stable reference. Its hierarchy is fractional-N synthesizer > PLL-based clock generator > clock synthesizer > clock and timing IC > semiconductor. This technology is particularly useful when a system needs a precise communications reference without relying on a separate crystal oscillator for every output frequency. Differential PECL outputs provide complementary signals suited to high-speed digital clocking and optical-transponder systems.
The SY87729LHY operates from a 3.3V supply and synthesizes frequencies from 10MHz to 365MHz using a single reference source. The verified search material specifically describes a 27MHz reference input and a maximum output of 365MHz. It generates the correct differential PECL reference required by the Micrel SY87721L combined clock-and-data-recovery and clock-multiplier-unit device, whose associated data rate range extends from 10Mbps to 2.7Gbps.
Fractional-N synthesis permits accurate generation of transport-related reference frequencies with or without forward-error correction. This is valuable in systems requiring standards-compliant downstream data units even when the associated upstream interface produces no signal. Exact phase-noise, jitter, reference-input, output-frequency, and divider specifications are not included in the supplied excerpts and must be confirmed in the manufacturer datasheet before final timing-budget approval.
Typical uses include optical transponders, SONET-compatible transport equipment, Ethernet-compatible clocking systems, and other communications links driven by the SY87721L. In these applications, the synthesizer establishes the local reference required by the downstream CDR/CMU, while the 365MHz upper output range provides headroom for demanding clock rates. Board-level signal integrity and differential clock routing remain essential because high-speed edge quality is not determined by output frequency alone.
Designers should place the input, output, and bypass connections as shown in the manufacturer application guidance, maintain short return paths, and use controlled-impedance routing for differential PECL pairs. The exposed pad should be connected to the ground plane according to the datasheet thermal and layout instructions. Because detailed termination and decoupling values were not supplied here, those values must be taken directly from the SY87729L manufacturer datasheet rather than inferred.
This product summary combines verified manufacturer and distributor information, pricing available as of 2026-10-28, same-family replacement information, and practical guidance for evaluating the SY87729LHY. It highlights where verified data is complete and marks unresolved electrical, environmental, pin-level, and lifecycle details rather than presenting unsupported assumptions as specifications.
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Các biến thể trong loạt này
Các mẫu cùng loạt có thể lắp đặt dễ dàng tương thích với SY87729LHY (cùng hình factor và footprint) — khác nhau ở Package.
SY87729LHI
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SY87729LHY Thông số kỹ thuật
| Device Type | Fractional-N frequency synthesizer and clock synthesizer |
| Điện áp cung cấp | 3.3 V |
| Supply Voltage Range | 3.15 V to 3.45 V |
| Output Frequency Range | 10 MHz to 365 MHz |
| Reference Input Frequency | 27 MHz |
| Output Logic | Differential PECL |
| Architecture | Rate-independent fractional-N synthesizer |
| Số lượng chân | 32 pins |
| Hộp | 32-pin TQFP with exposed pad |
| Kiểu lắp đặt | Surface mount |
| Compatible Clock and Data Recovery Device | SY87721L |
| Associated Data Rate Range | 10 Mbps to 2.7 Gbps |
| RoHS Compliance | unknown |
| REACH Compliance | unknown |
| AEC-Q100 Qualification | not_applicable |
Hướng dẫn cấu hình chân SY87729LHY 32-pin tqfp with exposed pad
Cấu hình chân cho SY87729LHY (32-pin tqfp with exposed pad gói). Số thứ tự chân, chức năng và sơ đồ kết nối được xác định trong tài liệu thông số kỹ thuật của nhà sản xuất. Tham khảo nó để biết footprint và hướng dẫn hàn chính xác.
Không có dữ liệu chân cụ thể sẵn có cho SY87729LHY.
Tham khảo: tài liệu kỹ thuật cho cấu hình chân đầy đủ.
Ứng dụng tiêu biểu
SY87729LHY phù hợp cho 6 Áp dụngs: Optical Transponder Timing, SONET-Compatible Transport Systems, Ethernet-Compatible Clocking, High-Speed Backplane Clocking, Clock Multiplier and CDR Support, Instrumentation Clock Reference.
Optical Transponder Timing
The SY87729LHY fits optical transponder timing because it generates an exactly correct reference for standards-compliant downstream protocol data units, even when the upstream interface produces no signal. Its fractional-N architecture uses a 27MHz reference to produce differential PECL outputs across 10MHz to 365MHz. This is useful where the transponder must maintain a valid local reference independent of incoming traffic. The principal design check is the complete communications timing budget, including reference jitter, PECL termination, and the exact protocol frequency required by the associated CDR/CMU.
Được đề xuất
SONET-Compatible Transport Systems
The SY87729LHY is suitable for transport-clock subsystems that require a programmable, standards-compliant reference derived from one oscillator. Its 3.3V operation and 10MHz-to-365MHz synthesis range cover the clocking role described for the SY87721L in communications equipment. Using one synthesized differential PECL reference can simplify clock distribution compared with maintaining multiple unrelated oscillators. Designers must still verify the required transport rate, jitter contribution, reference accuracy, and whether forward-error correction changes the synthesized frequency requirement.
Được đề xuất
Ethernet-Compatible Clocking
The SY87729LHY can provide the differential reference clock required by communications clocking chains based on the SY87721L. Its fractional-N synthesis supports exact generation of transport-related frequencies from a single 27MHz source, while the 365MHz maximum output provides substantial range for high-rate designs. In an Ethernet-oriented subsystem, the device may simplify the relationship between an external reference and a downstream CDR/CMU. Before deployment, verify the required line rate, recovery range, jitter budget, and implementation standards supported by the complete transceiver architecture.
Được đề xuất
High-Speed Backplane Clocking
The SY87729LHY is applicable where a board requires a locally generated differential PECL reference for high-speed digital timing. A 27MHz reference can be synthesized into outputs spanning 10MHz to 365MHz, providing flexibility across multiple communication modes within the same design. Differential routing helps correlate the two clock edges when the receiver is appropriately terminated and the PCB meets impedance requirements. The design must account for insertion loss, skew between the differential pair, return loss, and reference-jitter accumulation; those detailed values were not present in the supplied excerpts.
Được đề xuất
Clock Multiplier and CDR Support
The SY87729LHY was designed to generate the reference frequency used by the SY87721L combined clock-and-data-recovery and clock-multiplier-unit device. That relationship makes it suitable for systems operating from 10Mbps to 2.7Gbps when the downstream architecture uses this Micrel timing chain. The synthesizer separates reference generation from clock multiplication and recovery, allowing the reference to remain correct even during upstream signal absence. Board-level validation should confirm lock range, loop bandwidth, jitter transfer, and startup behavior for the selected SY87721L configuration.
Được đề xuất
Instrumentation Clock Reference
The SY87729LHY can serve as a programmable clock source in laboratory or industrial instrumentation that requires multiple derived frequencies from a common 27MHz reference. Its 10MHz-to-365MHz fractional-N output range provides flexibility for driving compatible timing and communications blocks, while the differential PECL interface can offer useful noise and edge behavior on a controlled board. The principal limitations are that exact output-divider settings, channel configuration, jitter, and output-drive specifications must be taken from the manufacturer datasheet rather than inferred from the output-frequency range.
Được đề xuất
Tóm tắt các sản phẩm được đề xuất
Dữ liệu tham khảo kỹ thuật cho SY87729LHY — so sánh, hướng dẫn thiết kế và thông tin tuân thủ.
Hướng dẫn chọn lựa
So sánh với các sản phẩm thay thế
| Tham số | Sản phẩm này | SY87729LHI |
|---|---|---|
| Package | 32-pin TQFP with exposed pad | TQFP - same package and terminal compatibility |
| Brand | Microchip Technology | Microchip Technology |
| Device Function | 3.3V fractional-N frequency synthesizer | Fractional-N clock synthesizer with consistent main performance characteristics |
| Drop-In Compatibility | Primary ordering target | Compatible according to supplied cross-reference evidence |
Bảo phân biệt quan trọng
- Integrated fractional-N synthesis for communications references (vsSY87729LHI)
- Exact reference generation during upstream signal absence (vsSY87729LHI)
- Broad synthesized output range from one reference (vsSY87729LHI)
Ghi chú thiết kế
Route each differential PECL output as a tightly coupled impedance-controlled pair with a continuous reference plane beneath it. Minimize stubs, vias, and unnecessary branch loads because discontinuities can degrade edge quality and return loss. The supplied sources do not specify the required characteristic impedance, so the PCB stackup and interface standard must be established from the manufacturer datasheet and receiver requirements rather than assumed.
Follow the manufacturer’s recommended supply decoupling and exposed-pad grounding arrangement. The verified operating range is 3.15V to 3.45V, so routing and transient margins should be evaluated across that full range rather than only at nominal 3.3V. Place bypass capacitors close to the supply pins and provide a low-impedance ground return to control supply noise, although exact capacitance values are not present in the supplied excerpts.
Build a complete jitter budget that includes the 27MHz reference, the fractional-N synthesizer, the SY87721L clock-and-data-recovery path, and the downstream receiver. Verify differential skew and termination against the complete communications system because a 365MHz output capability alone does not guarantee compliance with a specific protocol. Request the manufacturer’s phase-noise and output-jitter curves before defining the final timing margin.
Do not treat SY87729LHY-TR as a distinct functional upgrade merely because it appears in cross-reference results; the supplied evidence indicates the same core device with a different ordering or shipping configuration. Likewise, do not assume SY87729LHI is qualified for every SY87729LHY application without checking temperature grade, screening, and approved-part requirements. These suffix distinctions can affect procurement even when the footprint is unchanged.
Thông tin tuân thủ
The supplied verified web excerpts do not state RoHS, REACH, AEC-Q100, lead-free, halogen-free, or conflict-minerals status. The SY87729L is a communications clock-generation IC rather than an automotive-qualified device, so AEC-Q100 is marked not applicable; all other unsupported compliance claims remain unknown.
