SC5506A Operating & Programming Manual
Rev 2.1.1
15
Setting the Device Standby Mode
DEVICE_STANDBY (0x15)
–
For each channel, writing 0x01 to this register will power-down the analog/RF
circuitry. Writing 0x00 to this register will enable the analog/RF circuitry and the channel will return to its
last programmed state.
Setting the Reference Clock
REFERENCE_MODE (0x16)
- This register sets the behavior of the reference clock section. Bit 1 enables (1)
or disables (0) the output reference signal, and Bit 0 enables (1) or disables (0) the device to phase-lock
to an external source. It is important that if the device is not intended to lock externally, the external
source connection should be removed from the “ref in” connector. Even with external locking disabled,
the presence of a large signal from the external source on the reference input terminal could potentially
modulate the internal references, causing a spur offset in the RF signal.
Writing to the User EEPROM
USER_EEPROM_WRITE (0x1B)
- There is an onboard 32 kilobyte EEPROM for the user to store data. User
data is sent one byte at a time and is contained in the last (least significant) byte of the three bytes of data
written to the register. The other two bytes contain the write address in the EEPROM. For example, to
write user data 0x22 into address 0x1F00 requires writing 0x1F0022 to this register.
Setting the Reference DAC Value
REFERENCE_DAC_SETTING (0x1D)
-
The frequency precision of the device’s 10 MHz TCXO is set by the
device internally and the factory calibrated unsigned 14 bit value is written to the reference DAC on
power-up from the EEPROM. The user may choose to write a different value to the reference DAC by
accessing this register for example, to correct for long-term accuracy drift.
Storing the Startup State
STORE_STARTUP_STATE (0x23)
–
Writing to this register will save the current device state as the new
default power on (startup) state. All data written to this register will be ignored as only the write command
is needed to initiate the save.
Setting the RF ALC DAC Value
SET_ALC_DAC_VALUE (0x24)
- Writing a 14 bit control word to the ALC DAC register adjusts output
amplitude. This is useful when the user wants to make minute adjustments to the power level.
