The CDCEL824 is a modular PLL-based low-cost, high-performance, programmable clock
synthesizer, multiplier, and divider. It generates up to four output clocks from a single input
frequency. Each output can be programmed in-system for any clock frequency up to 201 MHz, using up
to two independent configurable PLLs.
The CDCEL824 has a separate output supply pins, VDDOUT, which are
The input accepts an external crystal or LVCMOS clock signal. In case of a crystal input,
an on-chip load capacitor is adequate for most applications. The value of the load capacitor is
programmable from 0 pF to 20 pF.
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 27-MHz reference input frequency, for example.
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 nonvolatile EEPROM programming for easy customization of the device
in the application. It is preset to a factory default configuration and can be reprogrammed to a
different application configuration before it goes onto the PCB or reprogrammed by in-system
programming. All device settings are programmable through the SDA/SCL bus, a 2-wire serial
Three free programmable control inputs, S0, S1, and S2, can be used to select different
frequencies, or other control features like outputs disable to low, outputs in high-impedance
state, power down, PLL bypass, and so forth.
The CDCx824 operates in a 1.8-V environment in a temperature range of –40°C to
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