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DESCRIPTION (CONTINUED)

CDCE906

SCAS814H – NOVEMBER 2005 – REVISED DECEMBER 2007

To achieve an independent output frequency the reference divider M and the feedback divider N for each PLL

can be set to values from 1 up to 511 for the M-Divider and from 1 up to 4095 for the N-Divider. The PLL-VCO

(voltage controlled oscillator) frequency than is routed to the free programmable output switching matrix to any of

the six outputs. The switching matrix includes an additional 7-bit post-divider (1-to-127) and an inverting logic for

each output.

The deep M/N divider ratio allows the generation of zero ppm clocks from any reference input frequency (e.g., a

27 MHz).

The CDCE906 includes three PLLs of those one supports SSC (spread-spectrum clocking). PLL1, PLL2, and

PLL3 are designed for frequencies up to 167 MHz and optimized for zero-ppm applications with wide divider

factors.

PLL2 also supports center-spread and down-spread spectrum clocking (SSC). This is a common technique to

reduce electro-magnetic interference. Also, the slew-rate controllable (SRC) output edges minimize EMI noise.

Based on the PLL frequency and the divider settings, the internal loop filter components will be automatically

adjusted to achieve high stability and optimized jitter transfer characteristic of the PLL.

The device supports non-volatile EEPROM programming for easy-customized application. It is preprogrammed

with a factory default configuration (see Figure 13) and can be reprogrammed to a different application

configuration before it goes onto the PCB or reprogrammed by in-system programming. A different device setting

is programmed via the serial SMBus interface.

Two free programmable inputs, S0 and S1, can be used to control for each application the most demanding logic

control settings (outputs disable to low, outputs 3-state, power down, PLL bypass, etc).

supplies can be 2.3 V to 3.6 V. At output voltages lower than 3.3 V, the output drive current is limited.

The CDCE906 is characterized for operation from 0

°C to 70°C.

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