2.4

CHARGE PUMP CONTROL WORD (CP_WORD)

MSB

LSB

AUX_CP_GAIN

MAIN_CP_GAIN

AUX_PD_POL

MAIN_PD_POL

BIT

LOCATION

FUNCTION

0

1

AUX_CP_GAIN

MAIN_R[17]

Aux Charge Pump Current Gain

LOW

HIGH

MAIN_CP_GAIN

MAIN_R[16]

Main Charge Pump Current Gain

LOW

HIGH

AUX_PD_POL

MAIN_R[15]

Aux Phase Detector Polarity

Negative

Positive

MAIN_PD_POL

MAIN_R[14]

Main Phase Detector Polarity

Negative

Positive

AUX_CP_GAIN (MAIN_R[17]) and MAIN_CP_GAIN (MAIN_R[16]) are used to select charge pump current magnitude either low

gain mode (160 µA typ) or high gain mode (1600 µA typ)

AUX_ PD_POL (MAIN_R[15]) and MAIN_ PD_POL (MAIN_R[14]) are respectively set to one when Aux or Main VCO

characteristics are positive as in (1) below. When VCO frequency decreases with increasing control voltage (2) PD_POL should

set to zero.

2.4.1

VCO Characteristics

10012914

2.4.2

Phase Comparator and Internal Charge Pump Characteristics

(AUX_PD_POL/MAIN_PD_POL = 1)

10012915

Note 15: fr is phase detector input from reference counter. fp is phase detector input from programmable N counter.

Phase difference detection range: - 2

π to+2pπ.

The minimum width pump up and pump down current pulses occur at the CPo pin when the loop is locked.

2.5

F

FoLD

Fo/LD OUTPUT STATE

32

1

0

AUX_R[17]

AUX_R[16]

AUX_R[15]

AUX_R[14]

0

0

0

0

“0”

0

0

0

1

“1”

0

0

1

X

Main Lock Detect

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