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CDCE813-Q1

SNAS705 – JANUARY 2017

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Copyright © 2017, Texas Instruments Incorporated

9.3 Feature Description

9.3.1 Control Terminal Configuration

The CDCE813-Q1 device 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 functions:

•

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

BITS

PLL1 SETTING

Y1 SETTING

Control function

PLL frequency

selection

SSC selection

Output Y2 and Y3

selection

Output Y1 and power-down selection

(1)

Center and down-spread, Frequency0, Frequency1, State0, and State1 are user-definable in PLL1

configuration register.

SSCx [3 BITS]

CENTER

DOWN

SSC SELECTION (CENTER AND 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%

(1)

Frequency0 and Frequency1 can be any frequency within the

FSx

FUNCTION

0

Frequency 0

1

Frequency 1

(1)

State0 or State1 selection is valid for both outputs of the

corresponding PLL module and can be power down, Hi-Z state, low,

or active.

Y2, Y3

FUNCTION

0

State 0

1

State 1