CS2000-CP

32

DS761F1

8.7.2

AUX PLL Lock Output Configuration (AuxLockCfg)

When the AUX_OUT pin is configured as a lock indicator (AuxOutSrc[1:0] = 11), this bit configures the

AUX_OUT driver to either push-pull or open drain. It also determines the polarity of the lock signal. If

AUX_OUT is configured as a clock output, the state of this bit is disregarded.

Note:

AUX_OUT is an unlock indicator, signalling an error condition when the PLL is unlocked. There-

fore, the pin polarity is defined relative to the unlock condition.

8.7.3

Reference Clock Input Divider (RefClkDiv[1:0])

Selects the input divider for the timing reference clock.

8.8

Function Configuration 2 (Address 17h)

8.8.1

Enable PLL Clock Output on Unlock (ClkOutUnl)

Defines the state of the PLL output during the PLL unlock condition.

8.8.2

Low-Frequency Ratio Configuration (LFRatioCfg)

Determines how to interpret the currently indexed 32-bit User Defined Ratio when the dynamic ratio based

Hybrid PLL Mode is selected (either manually or automatically, see section 5.3.5 on page 21).

Note:

When the static ratio based Frequency Synthesizer Mode is selected (either manually or auto-

matically), the currently indexed User Defined Ratio will always be interpreted as a 12.20 fixed point value,

regardless of the state of this bit.

AuxLockCfg

AUX_OUT Driver Configuration

0

Push-Pull, Active High (output ‘high’ for unlocked condition, ‘low’ for locked condition).

1

Open Drain, Active Low (output ‘low’ for unlocked condition, high-Z for locked condition).

Application:

“Auxiliary Output” on page 23

RefClkDiv[1:0]

Reference Clock Input Divider

REF_CLK Frequency Range

00

÷4.

32 MHz to 56 MHz (50 MHz with XTI)

01

÷ 2.

16 MHz to 28 MHz

10

÷ 1.

8 MHz to 14 MHz

11

Reserved.

Application:

“Internal Timing Reference Clock Divider” on page 14

76543210

Reserved

Reserved

Reserved

ClkOutUnl

LFRatioCfg

Reserved

Reserved

Reserved

ClkOutUnl

Clock Output Enable Status

0

Clock outputs are driven ‘low’ when PLL is unlocked.

1

Clock outputs are always enabled (results in unpredictable output when PLL is unlocked).

Application:

“PLL Clock Output” on page 23

LFRatioCfg

Ratio Bit Encoding Interpretation when Input Clock Source is CLK_IN

0

20.12 - High Multiplier.

1

12.20 - High Accuracy.

Application:

“User Defined Ratio (RUD), Hybrid PLL Mode” on page 19