ADF5902

Data Sheet

Rev. 0 | Page 26 of 39

DB31 DB30 DB29 DB28 DB27 DB26 DB25 DB24 DB23 DB22 DB21 DB20 DB19 DB18 DB17 DB16 DB15 DB14 DB13 DB12 DB11 DB10 DB9 DB8 DB7 DB6 DB5 DB4 DB3 DB2

DB1

DB0

00

00

00

0

1

0

1

C4(1) C3(1) C2(0) C1(0)

CONTROL

BITS

RESERVED

C5(0)

CHARGE PUMP

CURRENT

CC3

CC2

CC1

CC0

CTRI

0

0

0

000

0

0

0

0

5.1kΩ

00

00

0.28

00

01

0.56

00

10

0.84

00

11

1.12

01

00

1.40

01

01

1.68

01

10

1.96

01

11

2.24

10

00

2.52

10

01

2.80

10

10

3.08

10

11

3.36

11

00

3.64

11

01

3.92

11

10

4.20

11

11

4.48

CTRI

CP

TRISTATE

0

DISABLED

1

ENABLED

CC3

CC2

CC1

CC0

0

0

RESERVED

Figure 37. Register 12 (R12)

REGISTER 12

Control Bits

With Bits[C5:C1] set to 01100, Register R12 is programmed.

Figure 37 shows the input data format for programming this

register.

Reserved

Bits[DB31:DB21] and Bit DB16 are reserved and must be set as

shown in Figure 37.

Charge Pump Current Setting

Bits[DB20:DB17] set the charge pump current (see Figure 37). Set

these bits to the charge pump current that the loop filter is

designed with. The best practice is to design the loop filter for a

charge pump current of 2.24 mA or 2.52 mA and then use the

programmable charge pump current to adjust the frequency

response. See the Reference Doubler section for information on

setting the charge pump current when the doubler is enabled.

Charge Pump Tristate

When Bit DB15 is set to 1, the charge pump is placed in tristate

mode. For normal charge pump operation, set this bit to 0.