Datasheet

AD9601
Rev. 0 | Page 21 of 32
HARDWARE INTERFACE
The pins described in Table 8 comprise the physical interface
between the user’s programming device and the serial port of
the AD9601. All serial pins are inputs, which is an open-drain
output and should be tied to an external pull-up or pull-down
resistor (suggested value of 10 kΩ).
This interface is flexible enough to be controlled by either
PROMS or PIC microcontrollers as well. This provides the user
with an alternate method to program the ADC other than a SPI
controller.
If the user chooses not to use the SPI interface, some pins serve
a dual function and are associated with a specific function when
strapped externally to AVDD or ground during device power-
on. The
Configuration Without the SPI section describes the
strappable functions supported on the AD9601.
CONFIGURATION WITHOUT THE SPI
In applications that do not interface to the SPI control registers,
the SPI SDIO/DCS and SPI SCLK/DFS pins can alternately
serve as standalone CMOS-compatible control pins. When the
device is powered up, it is assumed that the user intends to use
the pins as static control lines for the duty cycle stabilizer. In
this mode, the SPI CSB chip select should be connected to
ground, which disables the serial port interface.
Table 9. Mode Selection
Mnemonic
External
Voltage
Configuration
AVDD Duty cycle stabilizer enabled SPI SDIO/DCS
AGND Duty cycle stabilizer disabled
AVDD Twos complement enabled SPI SCLK/DFS
AGND Offset binary enabled
DON’T CARE
DON’T CAREDON’T CARE
DON’T CARE
SDIO
SCLK
CSB
t
S
t
DH
t
HI
t
CLK
t
LO
t
DS
t
H
R/W W1 W0 A12 A11 A10 A9 A8 A7
D5 D4 D3 D2 D1 D0
07100-019
Figure 44. Serial Port Interface Timing Diagram