CDCE925

CDCEL925

SCAS847F – JULY 2007 – REVISED MARCH 2010

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APPLICATION INFORMATION

CONTROL TERMINAL SETTING

The CDCE925/CDCEL925 has three user-definable control terminals (S0, S1, and S2) which allow external

control of device settings. They can be programmed to any of the following setting:

•

Spread spectrum clocking selection

→ spread type and spread amount selection

•

Frequency selection

→ switching between any of two user-defined frequencies

•

Output state selection

→ output configuration and power down control

The user can predefine up to eight different control settings. Table 1 and Table 2 explain these settings.

Table 1. Control Terminal Definition

External

PLL1 Setting

PLL2 Setting

Y1 Setting

Control Bits

Control

PLL Frequency

SSC

Output Y2/Y3

PLL Frequency

SSC

Output Y4/Y5

Output Y1 and

Function

Selection

Selection

Selection

Selection

Selection

Selection

Power-Down Selection

SSC SELECTION (CENTER/DOWN)

SSCx [3-Bits]

Center

Down

0

0

0

0% (off)

0% (off)

0

0

1

±0.25%

–0.25%

0

1

0

±0.5%

–0.5%

0

1

1

±0.75%

–0.75%

1

0

0

±1.0%

–1.0%

1

0

1

±1.25%

–1.25%

1

1

0

±1.5%

–1.5%

1

1

1

±2.0%

–2.0%

FSx

FUNCTION

0

Frequency0

1

Frequency1

YxYx

FUNCTION

0

State0

1

State1

(1)

Center/Down-Spread, Frequency0/1 and State0/1 are user-definable in PLLx Configuration Register;

(2)

(3)

State0/1 selection is valid for both outputs of the corresponding PLL module and can be power down,

3-state, low or active

Y1 SELECTION

Y1

FUNCTION

0

State 0

1

State 1

(1)

State0 and State1 are user definable in Generic Configuration

Register and can be power down, 3-state, low, or active.

10

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Product Folder Link(s): CDCE925 CDCEL925