AD9574: Ethernet/Gigabit Ethernet Clock Generator Data Sheet (Rev. B)9/1/2014737 K
Features and Benefits
- Redundant input reference clock capability
- Reference monitoring function
- Fully integrated VCO/PLL core
- Jitter (rms)
- 0.234 ps rms jitter (10 kHz to 10 MHz) at 156.25 MHz
- 0.243 ps rms jitter (12 kHz to 20 MHz) at 156.25 MHz
- Input frequency: 19.44 MHz or 25 MHz
- Preset frequency translations
- Using a 19.44 MHz input reference
- 19.44 MHz, 38.88 MHz, 77.76 MHz, 155.52 MHz
- Using a 25 MHz input reference
- 25 MHz, 33.33 MHz, 50 MHz, 66.67 MHz, 80 MHz, 100 MHz, 125 MHz, 133.3 MHz, 156.25 MHz, 160 MHz, 312.5 MHz
- Using a 19.44 MHz input reference
- Output drive formats: HSTL, LVDS, HCSL, and 1.8 V and 3.3 V CMOS
- Integrated loop filter (requires a single external capacitor)
- 2 copies of reference clock output
- Device configuration via strapping pins (PPRx)
- Space-saving 7 mm × 7 mm 48-lead LFCSP
- 3.3 V operation
The AD9574 provides a multiple output clock generator function comprising a dedicated phase-locked loop (PLL) core optimized for Ethernet and gigabit Ethernet line card applications. The integer-N PLL design is based on the Analog Devices, Inc., proven portfolio of high performance, low jitter frequency synthesizers to maximize network performance. The AD9574 also benefits other applications requiring low phase noise and jitter performance.
Configuring the AD9574 for a particular application requires only the connection of external pull-up or pull-down resistors to the appropriate pin program reader pins (PPRx). These pins provide control of the internal dividers for establishing the desired frequency translations, clock output functionality, and input reference functionality. Connecting an external 19.44 MHz or 25 MHz oscillator to one or both of the REF0_P/REF0_N or REF1_P/REF1_N reference inputs results in a set of output frequencies prescribed by the PPRx pins. Connecting a stable clock source (8 kHz/10 MHz/19.44 MHz/25 MHz/38.88 MHz) to the monitor clock input enables the optional monitor circuit providing quality of service (QoS) status for REF0 or REF1.
The PLL section consists of a low noise phase frequency detector (PFD), a precision charge pump (CP), a partially integrated loop filter (LF), a low phase noise voltage controlled oscillator (VCO), and feedback and output dividers. The divider values depend on the PPRx pins. The integrated loop filter requires only a single external capacitor connected to the LF pin.
The AD9574 is packaged in a 48-lead 7 mm × 7 mm LFCSP, requiring only a single 3.3 V supply. The operating temperature range is −40°C to +85°C.
- Ethernet line cards, switches, and routers
- SATA and PCI express
- Low jitter, low phase noise clock generation
Product Lifecycle Recommended for New Designs
This product has been released to the market. The data sheet contains all final specifications and operating conditions. For new designs, ADI recommends utilization of these products.
Evaluation Kits (1)
The AD9574 evaluation board is a compact, easy-to-use platform for evaluating all features of the AD9574 clock generator.
Features & Benefits
Contact the Factory for Availability.
- Simple power connection using 6 V wall adapter and on-board switching and LDO voltage regulator.
Regulator easily bypassed for power measurements
- 12 ac-coupled SMA output connectors
- SMA input connections for:
2 single-ended reference input
Reference Monitor clock input
- On-board provisions for two 25 MHz OCXOs, providing reference input signals
- On-board PLL loop filter
- Easy access to digital I/O and diagnostic signals via I/O header
- Status LEDs for diagnostic signals
- On-board shunt/jumper blocks for configuration of pin programmable functions
Documentation & Resources
AD9574 Evaluation Board User Guide2/8/2021WIKI
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