CDCE937

CDCEL937

SLAS564F – AUGUST 2007 – REVISED MARCH 2010

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APPLICATION INFORMATION

CONTROL TERMINAL SETTING

The CDCE937/CDCEL937 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

Control

PLL1 Setting

PLL2 Setting

PLL3 Setting

Y1 Setting

Bits

PLL

Output

PLL

Output

PLL

Output

Output Y1 and

Control

SSC

SSC

SSC

Frequency

Y2/Y3

Frequency

Y4/Y5

Frequency

Y6/Y7

Power-Down

Function

Selection

Selection

Selection

Selection

Selection

Selection

Selection

Selection

Selection

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): CDCE937 CDCEL937