CDCE937是TI公司的一款扩频时钟产品，CDCE937是具有 2.5V 或 3.3V LVCMOS 输出的可编程 3-PLL VCXO 时钟合成器，本页介绍了CDCE937的产品说明、应用、特性等，并给出了与CDCE937相关的TI元器件型号供参考。
CDCE937 - 具有 2.5V 或 3.3V LVCMOS 输出的可编程 3-PLL VCXO 时钟合成器 - 扩频时钟 - 时钟发生器 - TI公司（Texas Instruments，德州仪器）
The CDCE937 and CDCEL937 are modular PLL-based low cost, high-performance, programmable clock synthesizers, multipliers and dividers. They generate up to 7 output clocks from a single input frequency. Each output can be programmed in-system for any clock frequency up to 230MHz, using up to three independent configurable PLLs.
The CDCx937 has separate output supply pins, VDDOUT, which is 1.8V for CDCEL937 and to 2.5V to 3.3V for CDCE937.
The input accepts an external crystal or LVCMOS clock signal. If an external crystal is used, an on-chip load capacitor is adequate for most applications. The value of the load capacitor is programmable from 0 to 20pF. Additionally, an on-chip VCXO is selectable which allows synchronization of the output frequency to an external control signal, that is, PWM signal.
The deep M/N divider ratio allows the generation of zero ppm audio/video, networking (WLAN, BlueTooth, Ethernet, GPS) or Interface (USB, IEEE1394, Memory Stick) clocks from a reference input frequency such as 27MHz.
All PLLs supports SSC (Spread-Spectrum Clocking). SSC can be Center-Spread or Down-Spread clocking which is a common technique to reduce electro-magnetic interference (EMI).
Based on the PLL frequency and the divider settings, the internal loop filter components are automatically adjusted to achieve high stability and optimized jitter transfer characteristic of each PLL.
The device supports non-volatile EEPROM programming for ease-customized application. It is preset to a factory default configuration (see the Default Device Configuration section). It can be reprogrammed to a different application configuration before PCB assembly, or reprogrammed by in-system programming. All device settings are programmable through SDA/SCL bus, a 2-wire serial interface.
Three programmable control inputs, S0, S1 and S2, can be used to control various aspects of operation including frequency selection changing the SSC parameters to lower EMI, PLL bypass, power down, and choosing between low level or 3-state for output-disable function.
The CDCx937 operates in 1.8V environment. It is characterized for operation from –40°C to 85°C.
- Member of Programmable Clock Generator Family
- CDCE913/CDCEL913: 1-PLL, 3 Outputs
- CDCE925/CDCEL925: 2-PLL, 5 Outputs
- CDCE937/CDCEL937: 3-PLL, 7 Outputs
- CDCE949/CDCEL949: 4-PLL, 9 Outputs
- In-System Programmability and EEPROM
- Serial Programmable Volatile Register
- Nonvolatile EEPROM to Store Customer Setting
- Flexible Input Clocking Concept
- External Crystal: 8 MHz to 32 MHz
- On-Chip VCXO: Pull Range ±150 ppm
- Single-Ended LVCMOS up to 160 MHz
- Selectable Output Frequency up to 230 MHz
- Low-Noise PLL Core
- Integrated PLL Loop Filter Components
- Low Period Jitter (Typ 60 ps)
- Separate Output Supply Pins
- CDCE937: 3.3 V and 2.5 V
- CDCEL937: 1.8 V
- 1.8-V Device Power Supply
- Flexible Clock Driver
- Three User-Definable Control Inputs [S0/S1/S2] e.g., SSC Selection, Frequency Switching, Output Enable or Power Down
- Generates Highly Accurate Clocks for Video, Audio, USB, IEEE1394, RFID, Bluetooth™, WLAN, Ethernet™, and GPS
- Generates Common Clock Frequencies Used With TI DaVinci™, OMAP™, DSPs
- Programmable SSC Modulation
- Enables 0-PPM Clock Generation
- Wide Temperature Range –40° C to 85° C
- Packaged in TSSOP
- Development and Programming Kit for Easy PLL Design and Programming (TI Pro-Clock™)
- APPLICATIONS
- D-TV, HD-TV, STB, IP-STB, DVD-Player, DVD-Recorder, Printer
DaVinci, OMAP, Pro-Clock are trademarks of Texas Instruments. Bluetooth is a trademark of Bluetooth SIG. Ethernet is a trademark of Xerox Corporattion.
