AD9520-0 Datasheet, PDF (80/84 Pages) Analog Devices – 12 LVPECL/24 CMOS Output Clock Generator with Integrated 2.8 GHz VCO

AD9520-0
Table 57. System
Reg.
Addr
(Hex) Bit(s) Name
230 [3] Disable power-on SYNC
230 [2] Power-down SYNC
230 [1] Power-down distribution reference
230 [0] Soft SYNC
Description
Power-on SYNC mode. Used to disable the antiruntpulse circuitry.
[3] = 0; enable the antiruntpulse circuitry (default).
[3] = 1; disable the antiruntpulse circuitry.
Powers down the SYNC function.
[2] = 0; normal operation of the SYNC function (default).
[2] = 1; power-down SYNC circuitry.
Powers down the reference for the distribution section.
[1] = 0; normal operation of the reference for the distribution section (default).
[1] = 1; powers down the reference for the distribution section.
The soft SYNC bit works the same as the SYNC pin, except that the polarity of the bit
is reversed; that is, a high level forces selected channels into a predetermined static
state, and a 1-to-0 transition triggers a SYNC.
[0] = 0; same as SYNC high.
[0] = 1; same as SYNC low.
Table 58. Update All Registers
Reg.
Addr
(Hex) Bit(s) Name
Description
232 [0] IO_UPDATE This bit must be set to 1 to transfer the contents of the buffer registers into the active registers. This happens
on the next SCLK rising edge. This bit is self-clearing; that is, it does not have to be set back to 0.
[0] = 1 (self-clearing); update all active registers to the contents of the buffer registers.
Table 59. EEPROM Buffer Segment
Reg.
Addr
(Hex) Bit(s) Name
Description
A00 to
A16
EEPROM Buffer
Segment Register 1
to EEPROM Buffer
Segment Register 23
The EEPROM buffer segment section stores the starting address and number of bytes that are to be
stored and read back to and from the EEPROM. Because the AD9520 register space is noncontiguous,
the EEPROM controller needs to know the starting address and number of bytes in the AD9520 register
space to store and retrieve from the EEPROM. In addition, there are special instructions for the EEPROM
controller, operational codes (that is, IO_UPDATE and end-of-data) that are also stored in the EEPROM
buffer segment. The on-chip default setting of the EEPROM buffer segment registers is designed such
that all registers are transferred to/from the EEPROM, and an IO_UPDATE is issued after transfer. See the
Programming the EEPROM Buffer Segment section for more information.
Rev. 0 | Page 80 of 84