AD9520-2SLASHPCBZ datasheet(58/84 Pages) AD

58 / 84 page

AD9520-2

Rev. 0 | Page 58 of 84

EEPROM OPERATIONS

The AD9520 contains an internal EEPROM (nonvolatile memory).

The EEPROM can be programmed by users to create and store

a user-defined register setting file when the power is off. This

setting file can be used for power-up and chip reset as a default

setting. The EEPROM size is 512 bytes.

During the data transfer process, the write and read registers via

the serial port are generally not available except for one readback

To determine the data transfer state through the serial port in

SPI mode, users can read the value of STATUS_EEPROM (1 =

in process and 0 = completed).

In I2C mode, the user can address the AD9520 slave port with

the external I2C master (send an address byte to the AD9520). If

the AD9520 responds with a no acknowledge bit, the data transfer

process is not done. If the AD9520 responds with an acknowledge

bit, the data transfer process is completed. The user can monitor

the STATUS_EEPROM register or program the STATUS pin to

monitor the status of the data transfer.

WRITING TO THE EEPROM

The EEPROM cannot be programmed directly through the serial

port interface. To program the EEPROM and store a register

setting file, do the following:

Program the AD9520 registers to the desired circuit state. If

the user wants the PLL to lock automatically after power-up,

the VCO calibration now bit (0x018[0]) must be set to 1.

This allows VCO calibration to start automatically after

must be present during VCO calibration.

Program the EEPROM buffer registers, if necessary (see

the Programming the EEPROM Buffer Segment section).

This is only necessary if users want to use the EEPROM to

control the default setting of some (but not all) of the

AD9520 registers, or if they want to control the register

setting update sequence during power-up or chip reset.

Set the enable EEPROM write bit (0xB02[0]) to 1 to enable

the EEPROM.

Set the REG2EEPROM bit (0xB03[0]) to 1.

Set the IO_UPDATE bit (0x232[0]) to 1, which starts the

process of writing data into the EEPROM to create the

EEPROM setting file. This enables the AD9520 EEPROM

controller to transfer the current register values, as well as

the memory address and instruction bytes from the EEPROM

buffer segment, into the EEPROM. After the write process

is completed, the internal controller sets 0xB03[0]

(REG2EEPROM) back to 0.

The readback register, STATUS_EEPROM (0xB00[0]),

is used to indicate the data transfer status between the

EEPROM and the control registers (0 = done/inactive;

1 = in process/active). At the beginning of the data transfer,

STATUS_EEPROM is set to 1 by the EEPROM controller

and cleared to 0 at the end of the data transfer. The user

can access STATUS_EEPROM through the STATUS pin

when the STATUS pin is programmed to monitor

STATUS_EEPROM. Alternatively, the user can monitor

the STATUS_EEPROM bit.

After the data transfer process is done (0xB00[0] = 0), set

the enable EEPROM write register (0xB02[0]) to 0 to

disable writing to the EEPROM.

To verify that the data transfer has completed correctly, the user

can verify that 0xB01[0] = 0. A value of 1 in this register indicates a

data transfer error.

READING FROM THE EEPROM

The following reset-related events can start the process of

restoring the settings stored in EEPROM to control registers.

When the EEPROM pin is set high, do any of the following:

Power-up the AD9520.

Perform a hardware chip reset by pulling the RESET pin

low and then releasing RESET.

Set the self-clearing soft reset bit (0x000[5]) to 1.

When the EEPROM pin is set low, set the self-clearing

Soft_EEPROM bit (0xB02[1]) to 1. The AD9520 then starts to

read the EEPROM and loads the values into the AD9520.

If the EEPROM pin is low during reset or power-up, the

EEPROM is not active, and the AD9520 default values are

loaded instead.

When using the EEPROM to automatically load the AD9520

(0x018[0]) must be set to 1 when the register values are written

to the EEPROM. This allows VCO calibration to start

automatically after register loading. A valid input reference

signal must be present during VCO calibration.

To verify that the data transfer has completed correctly, the user

can verify that 0xB01[0] = 0. A value of 1 in this register indicates a

data transfer error.

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