Datasheet

AD9524 Data Sheet
Rev. D | Page 34 of 56
EEPROM OPERATIONS
The AD9524 contains an internal EEPROM (nonvolatile memory).
The EEPROM can be programmed by the user 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. Descriptions of the EEPROM registers
that control EEPROM operation can be found in Table 58 and
Table 59.
During the data transfer process, the write and read registers are
generally not available via the serial port, except for one readback
bit: Status_EEPROM (Register 0xB00, Bit 0).
To determine the data transfer state through the serial port in
SPI mode, users can read the value of the Status_EEPROM bit
(1 = data transfer in process and 0 = data transfer complete).
In IC mode, the user can address the AD9524 slave port with
the external IC master (send an address byte to the AD9524). If
the AD9524 responds with a no acknowledge bit, the data transfer
was not received. If the AD9524 responds with an acknowledge bit,
the data transfer process is complete. The user can monitor the
Status_EEPROM bit or use Register 0x232, Bit 4 to program
the STATUS0 pin to monitor the status of the data transfer (see
Table 55).
To transfer all 512 bytes to the EEPROM, it takes approximately
46 ms. To transfer the contents of the EEPROM to the active
register, it takes approximately 40 ms.
RESET
, a hard reset (an asynchronous hard reset is executed by
briefly pulling
RESET
low), restores the chip either to the setting
stored in EEPROM (the EEPROM pin = 1) or to the on-chip
setting (the EEPROM pin = 0). A hard reset also executes a SYNC
operation, which brings the outputs into phase alignment
according to the default settings. When EEPROM is inactive (the
EEPROM pin = 0), it takes ~2 µs for the outputs to begin
toggling after
RESET
is issued. When EEPROM is active (the
EEPROM pin = 1), it takes ~40 ms for the outputs to toggle after
RESET
is brought high.
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, follow these steps:
1. Program the AD9524 registers to the desired circuit state.
If the user wants PLL2 to lock automatically after power-up,
the calibrate VCO bit (Bit 1, Register 0x0F3) must be set to 1.
This allows VCO calibration to start automatically after
register loading. Note that a valid input reference signal
must be present during VCO calibration.
2. Set the IO_Update bit (Bit 0, Register 0x234) to 1.
3. Program the EEPROM buffer registers, if necessary (see
the Programming the EEPROM Buffer Segment section).
This step is necessary only if users want to use the EEPROM
to control the default settings of some (but not all) of the
AD9524 registers, or if they want to control the register
setting update sequence during power-up or chip reset.
4. Set the enable EEPROM write bit (Bit 0, Register 0xB02)
to 1 to enable the EEPROM.
5. Set the REG2EEPROM bit (Bit 0, Register 0xB03) to 1. This
starts the process of writing data into the EEPROM to create
the EEPROM setting file. This enables the 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 bit REG2EEPROM
back to 0.
Bit 0 of the Status_EEPROM register (Register 0xB00) is used
to indicate the data transfer status between the EEPROM and
the control registers (1 = data transfer in process, and 0 = data
transfer complete). At the beginning of the data transfer, the
Status_EEPROM bit 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 via the STATUS0 pin when the STATUS0
pin is programmed to monitor the Status_EEPROM bit.
Alternatively, the user can monitor the Status_EEPROM bit
directly.
6. When the data transfer is complete (Status_EEPROM = 0),
set the enable EEPROM write bit (Bit 0 in Register 0xB02)
to 1. Clearing the enable EEPROM write bit to 0 disables
writing to the EEPROM.
To ensure that the data transfer has completed correctly, verify
that the EEPROM data error bit (Bit 0 in Register 0xB01) = 0.
A value of 1 in this bit indicates a data transfer error.
READING FROM THE EEPROM
The following reset-related events can start the process of
restoring the settings stored in the EEPROM to the control
registers. When the EEPROM_SEL pin is set high, do any of
the following to initiate an EEPROM read:
 Power up the AD9524.
 Perform a hardware chip reset by pulling the
RESET
pin
low and then releasing
RESET
.
 Set the self-clearing soft reset bit (Bit 5, Register 0x000) to 1.
When the EEPROM_SEL pin is set low, set the self-clearing
Soft_EEPROM bit (Bit 1, Register 0xB02) to 1. The AD9524 then
starts to read the EEPROM and loads the values into the AD9524
registers. If the EEPROM_SEL pin is low during reset or power-up,
the EEPROM is not active, and the AD9524 default values are
loaded instead.
When using the EEPROM to automatically load the AD9524
register values and lock the PLL, the calibrate VCO bit (Bit 1,
Register 0x0F3) 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.