ADF4368 datasheet(24/54 Pages) AD

24 / 54 page

Data Sheet

ADF4368

APPLICATIONS INFORMATION

analog.com

Rev. 0 | 24 of 54

a. Set the SDO_ACTIVE and CMOS_OV bits to a desired

state for future readback operations.

b. Program all register addresses in descending order,

REG0053 to REG0010. There are several required re-

served register field settings provided in Table 19 that are

required for proper device operation.

4. The ADF4368 remains in power-down mode until the PD_ALL

bit is programmed to 0. After PD_ALL is disabled, wait at least

10 μs for the VCO calibration circuitry and other circuit blocks to

settle before starting a VCO calibration.

5. A write to REG0010 starts a VCO autocalibration. At this point,

the device is fully operational and new frequencies can be

programmed as often as desired. The following steps are infor-

mation for PD_ALL and CE pin.

6. Setting PD_ALL to 1 power down the ADF4368, retaining the

latest programmed SPI settings and full SPI programming capa-

bility.

7. If only the state of PD_ALL was modified in Step 6, setting

PD_ALL to 0 returns the ADF4368 to the frequency program-

med in Step 5. After a 10 μs wait, all circuit blocks are

completely powered up internally. This 10 μs wait does not

include the frequency settling time associated with the loop filter

bandwidth.

8. Toggling the CE pin level causes the ADF4368 to return to

full power-down mode and return the SPI registers to the POR

state (see Step 2 and Step 3).

Programming Procedure

There are two different methods to power up the ADF4368. The

most commonly used method provided in the Standard Power-Up

and Initialization Sequence, Automatic VCO Calibration section is

mandatory on the initial device power-up.

The method provided in the Fast Power-Up and Initialization, Man-

ually Programmed VCO Calibration Settings (Optional) section is an

optional power-up procedure after the initial power-up.

Standard Power-Up and Initialization

Sequence, Automatic VCO Calibration

The following standard power-up and initialization sequence is the

recommended procedure to power up and program the ADF4368:

1. Follow Step 1 through Step 5 in the Power-Up and Initialization

Sequence section.

2. It is optional to monitor the status of the VCO calibration bits,

ADC_BUSY and FSM_BUSY. A VCO calibration is completed

when ADC_BUSY transitions from high to low, followed by

FSM_BUSY transitioning from high to low. Typical automatic

VCO calibration times range from 3 ms to 9 ms.

3. After the VCO calibration is complete, disable the VCO

calibration clocks by setting EN_DRCLK = EN_DNCLK =

EN_ADC_CLK = 0. Disabling the VCO calibration clocks re-

duces unwanted spurious content.

4. The PLL is locked when the lock detector sets the LKDET pin

and the LOCKED bit high.

5. When changing the frequency, do the following steps:

a. Program only the modified registers in the descending or-

der.

b. Write REG0010 to start a new VCO autocalibration as the

final step whether it is modified or not.

Fast Power-Up and Initialization, Manually

Programmed VCO Calibration Settings

(Optional)

The purpose of the fast power-up and initialization method is to

avoid the automatic VCO calibration time, which is typically 3 ms

to 9 ms. For fixed clock frequency converter applications, automatic

VCO calibration times are typically acceptable. For fast frequency

hopping applications, much shorter lock time is needed.

The following list provides the steps to record the VCO calibration

results on the initial power-up and then to manually program VCO

calibration settings on subsequent power ups:

1. On initial power up, follow the procedure in the Standard Pow-

er-Up and Initialization Sequence, Automatic VCO Calibration

section.

2. Record calibration results from the VCO_CORE, VCO_BAND,

and VCO_BIAS bit fields for each target frequency and store

the recorded results in memory. Note that each unique device

and frequency combination generates different VCO_CORE,

VCO_BAND, and VCO_BIAS values.

3. Subsequent power-up and initialization sequences (see the

Power-Up and Initialization Sequence section) can bypass the

automatic VCO calibration procedure by programming the over-

ride (O_VCO_CORE, O_VCO_BAND, and O_VCO_BIAS) and

manual (M_VCO_CORE, M_VCO_BAND, and M_VCO_BIAS)

VCO bits with the register settings provided in Table 18. All

other bit fields are programmed as usual.

4. When changing the frequency, program only the modified regis-

ters in descending order.

Table 18. Manually Programmed VCO Calibration Settings

Bit Fields

Value

EN_AUTOCAL

0x0

EN_DRCLK

0x0

EN_DNCLK

0x0

EN_ADC_CLK

0x0

O_VCO_CORE

0x1

O_VCO_BAND

0x1

O_VCO_BIAS

0x1

M_VCO_CORE

Program with recorded values

M_VCO_BAND

Program with recorded values

M_VCO_BIAS

Program with recorded values

ADF4368 Datasheet(PDF) 24 Page - Analog Devices

ADF4368 Datasheet(HTML) 24 Page - Analog Devices

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54

Datasheet Download

Link URL