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ADF4107BRUZ View Datasheet(PDF) - Analog Devices

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Description
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ADF4107BRUZ
ADI
Analog Devices ADI
ADF4107BRUZ Datasheet PDF : 20 Pages
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Data Sheet
INTERFACING
The ADF4107 has a simple SPI®-compatible serial interface for
writing to the device. CLK, DATA, and LE control the data
transfer. When LE (latch enable) goes high, the 24 bits that have
been clocked into the input register on each rising edge of CLK
are transferred to the appropriate latch. See Figure 2 for the
timing diagram and Table 5 for the latch truth table.
The maximum allowable serial clock rate is 20 MHz. This
means that the maximum update rate possible for the device is
833 kHz or one update every 1.2 µs. This is certainly more than
adequate for systems that have typical lock times in hundreds of
microseconds.
ADuC812 Interface
Figure 28 shows the interface between the ADF4107 and the
ADuC812 MicroConverter®. Since the ADuC812 is based on an
8051 core, this interface can be used with any 8051-based
microcontroller. The MicroConverter is set up for SPI master
mode with CPHA = 0. To initiate the operation, the I/O port
driving LE is brought low. Each latch of the ADF4107 needs a
24-bit word. This is accomplished by writing three 8-bit bytes
from the MicroConverter to the device. When the third byte
has been written, the LE input should be brought high to
complete the transfer.
On first applying power to the ADF4107, it needs four writes
(one each to the initialization latch, function latch, R counter
latch, and N counter latch) for the output to become active.
I/O port lines on the ADuC812 are also used to control power-
down (CE input) and to detect lock (MUXOUT configured as
lock detect and polled by the port input).
When operating in the mode described, the maximum
SCLOCK rate of the ADuC812 is 4 MHz. This means that the
maximum rate at which the output frequency can be changed is
166 kHz.
SCLOCK
MOSI
ADuC812
I/O PORTS
CLK
DATA
LE ADF4107
CE
MUXOUT
(LOCK DETECT)
Figure 28. ADuC812 to ADF4107 Interface
ADF4107
ADSP-2181 Interface
Figure 29 shows the interface between the ADF4107 and the
ADSP21xx digital signal processor. The ADF4107 needs a
24-bit serial word for each latch write. The easiest way to
accomplish this using the ADSP-21xx family is to use the
autobuffered transmit mode of operation with alternate
framing. This provides a means for transmitting an entire block
of serial data before an interrupt is generated. Set up the word
length for 8 bits and use three memory locations for each 24-bit
word. To program each 24-bit latch, store the three 8-bit bytes,
enable the autobuffered mode, and then write to the transmit
register of the DSP. This last operation initiates the autobuffer
transfer.
SCLOCK
DT
ADSP-21xx TFS
I/O FLAGS
CLK
DATA
LE ADF4107
CE
MUXOUT
(LOCK DETECT)
Figure 29. ADSP-21xx to ADF4107 Interface
PCB DESIGN GUIDELINES FOR CHIP SCALE
PACKAGE
The lands on the chip scale package (CP-20-6) are rectangular.
The printed circuit board pad for these should be 0.1 mm
longer than the package land length and 0.05 mm wider than
the package land width. The land should be centered on the
pad. This ensures that the solder joint size is maximized. The
bottom of the chip scale package has a central thermal pad.
The thermal pad on the printed circuit board should be at least
as large as this exposed pad. On the printed circuit board, there
should be a clearance of at least 0.25 mm between the thermal
pad and the inner edges of the pad pattern. This ensures that
shorting is avoided.
Thermal vias may be used on the printed circuit board thermal
pad to improve thermal performance of the package. If vias are
used, they should be incorporated in the thermal pad at 1.2 mm
pitch grid. The via diameter should be between 0.3 mm and
0.33 mm and the via barrel should be plated with 1 oz. copper
to plug the via.
The user should connect the printed circuit board thermal pad
to AGND.
Rev. D | Page 19 of 20
 

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