ADRF6806

Data Sheet

Rev. B | Page 20 of 36

Register 6—VCO Control and Enables

With R6[2:0] set to 110, the VCO control and enables register is

programmed as shown in Figure 39.

VCO band selection is normally selected based on BANDCAL

calibration; however, the VCO band can be selected directly using

Register 6. The VCO BS SRC determines whether the BANDCAL

calibration determines the optimum VCO tuning band or if the

external SPI interface is used to select the VCO tuning band

based on the value of the VCO band select.

The VCO amplitude can be controlled through Register 6. The

VCO amplitude setting can be controlled between 0 and 31

decimal, with a default value of 24.

The internal VCO can be disabled using Register 6. The internal

VCO LDO can be disabled if an external clean 3.0 V supply is

available.

The internal charge pump can be disabled through Register 6.

Normally, the charge pump is enabled.

CHARGE

PUMP

ENABLE

3.3V

SWITCH

ENABLE

VCO

ENABLE

VCO

SWITCH

VCO

BS

CSR

VBSRC

0

1

VCO EN

VCO LDO

ENABLE

VCO AMPLITUDE

VCO BAND SELECT

CHARGE PUMP ENABLE

VCO BAND CAL AND SW SOURCE CONTROL

BAND CAL (DEFAULT)

VCO SW

0

1

VCO SWITCH CONTROL FROM SPI

REGULAR (DEFAULT)

BAND CAL

SPI

VCO ENABLE

DISABLE

ENABLE (DEFAULT)

DB22 DB21

DB20

DB19

DB18

DB17

DB16

DB15 DB14 DB13 DB12 DB11 DB10

DB9

DB8 DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0

CONTROL BITS

DB23

CPEN

L3EN

VCO EN VCO SW VC5 VC4 VC3 VC2 VC1 VC0 VBSRC VBS5 VBS4 VBS3 VBS2 VBS1 VBS0 C3(1) C2(1) C1(0)

LVEN

0

1

LVEN

VCO LDO ENABLE

DISABLE

ENABLE (DEFAULT)

0

1

L3EN 3.3V SWITCH ENABLE

DISABLE

ENABLE (DEFAULT)

0

1

CPEN

DISABLE

ENABLE (DEFAULT)

0

1

00

0

VC5

VC4

VC3

VC2

VC1

00

00

0

...

...

...

...

...

...

...

...

...

...

...

...

...

...

...

1

011

1

...

63

VCO AMPLITUDE

0

...

...

0

110

0

24 (RECOMMENDED)

0

111

1

VC0

0

...

...

...

1

0

1

47

VBS5 VBS4 VBS3 VBS2 VBS1

00000

...

...

...

...

...

...

...

...

...

...

VCO BAND SELECT

FROM SPI

0

...

...

10000

32 (DEFAULT)

11111

VBS0

0

...

...

0

1

63

...

...

...

...

...

00

10

0

...

0

...

8 (DEFAULT)

Figure 39. VCO Control and Enables (R6)