Datasheet

Data Sheet AD5541/AD5542
Rev. F | Page 15 of 20
APPLICATIONS INFORMATION
OPTOCOUPLER INTERFACE
The digital inputs of the AD5541/AD5542 are Schmitt-triggered so
that they can accept slow transitions on the digital input lines.
This makes these parts ideal for industrial applications where it
may be necessary to isolate the DAC from the controller via
optocouplers. Figure 29 illustrates such an interface.
10kΩ
10µF
0.1µF
V
DD
V
OUT
V
DD
SCLK
POWER
10kΩ
V
DD
CS
CS
DIN
GND
SCLK
10kΩ
V
DD
DIN
5V
REGULATOR
AD5541/AD5542
07557-029
Figure 29. AD5541/AD5542 in an Optocoupler Interface
DECODING MULTIPLE AD5541/AD5542s
The
CS
pin of the AD5541/AD5542 can be used to select one of
a number of DACs. All devices receive the same serial clock and
serial data, but only one device receives the
CS
signal at any one
time. The DAC addressed is determined by the decoder. There is
some digital feedthrough from the digital input lines. Using a
burst clock minimizes the effects of digital feedthrough on the
analog signal channels.
Figure 30 shows a typical circuit.
AD5541/AD5542
CS
DIN
SCLK
V
OUT
AD5541/AD5542
CS
DIN
SCLK
V
OUT
AD5541/AD5542
CS
DIN
SCLK
V
OUT
AD5541/AD5542
CS
DIN
SCLK
V
OUT
V
DD
DGND
EN
CODED
ADDRESS
SCLK
DIN
ENABLE
DECODER
07557-030
Figure 30. Addressing Multiple AD5541/AD5542s