Datasheet

AD9577 Data Sheet
Rev. 0 | Page 40 of 44
DEFAULT FREQUENCY MAP AND OUTPUT
FORMATS
The power-up operation (without I
2
C programming) of the
AD9577 is represented by a default frequency map and output
formats (see Table 31).
Table 31. Default Parameter Values, f
PFD
= 25 MHz
Parameter Value Notes
PLL1
f
OUT0
= 156.25 MHz,
f
OUT1
= 125 MHz
Na 80 + 20 = 100
V0 4
D0 4
V1 4
D1 5
FORMAT1 000 OUT0/OUT1 are LVPECL
SyncCh01 0
PLL2
f
OUT2
= 100 MHz,
f
OUT3
= 33.333 MHz
Nb 80 + 16 = 96
FRAC 0
MOD 0
PD_SDM 1
Bleed 0
V2 4
D2 6
V3 4
D3 18
FORMAT2 000 OUT2/OUT3 are LVPECL
SyncCh23 0
SSCG
FracStep 0
NumSteps 0
CkDiv 0
Control
EnI2C 0
NewAcq 0
PDCH0 0
PDCH1 0
PDCH2 0
PDCH3 0
PDRefOut 0
PDPLL1 0
PDPLL2 0
R 0
Parameter Value Notes
Margining
These parameters are
applied only when the
MARGIN pin = high
PLL1
f
OUT0
= 156.25 MHz,
f
OUT1
= 125 MHz
Na 80 + 20 = 100
V0 4
D0 4
V1 4
D1 5
f
OUT0
156.25 MHz
f
OUT1
125 MHz
PLL2
f
OUT2
= 212.5 MHz,
f
OUT3
= 106.25 MHz
Nb 80 + 22 = 102
FRAC 0
MOD 0
V2 2
D2 6
V3 4
D3 6
I
2
C INTERFACE OPERATION
The AD9577 is programmed by a 2-wire, I
2
C-compatible serial bus
driving multiple peripherals. Two inputs, serial data (SDA) and
serial clock (SCL), carry information between any devices
connected to the bus. Each slave device is recognized by a unique
address. The slave address consists of the 7 MSBs of an 8-bit
word. The 7-bit slave address of the AD9577 is 1000000. The LSB
of the word sets either a read or write operation (see Figure 44).
Logic 1 corresponds to a read operation, and Logic 0
corresponds to a write operation.
To control the device on the bus, do the following protocol.
First, the master initiates a data transfer by establishing a start
condition, defined by a high-to-low transition on SDA while
SCL remains high, which indicates that an address/data stream
follows. All peripherals respond to the start condition and shift
the next eight bits (the 7-bit address and the R/
W
bit). The bits
are transferred from MSB to LSB. The peripheral that recognizes
the transmitted address responds by pulling the data line low
during the ninth clock pulse, which is known as the acknowledge
bit. All other devices withdraw from the bus at this point and
maintain an idle condition. The idle condition is where the device
monitors the SDA and SCL lines waiting for the start condition
and correct transmitted address. The R/
W
bit determines the
direction of the data. Logic 0 on the LSB of the first byte means
that the master writes information to the peripheral, and Logic 1
on the LSB of the first byte means that the master reads
information from the peripheral.