Datasheet

AD5306/AD5316/AD5326
Rev. F | Page 21 of 24
AD5306/AD5316/AD5326 AS A DIGITALLY
PROGRAMMABLE WINDOW DETECTOR
A digitally programmable upper/lower limit detector using two
of the DACs in the AD5306/AD5316/AD5326 is shown in
Figure 39. The upper and lower limits for the test are loaded to
DACs A and B, which, in turn, set the limits on the CMP04. If
the signal at the V
IN
input is not within the programmed
window, an LED indicates the fail condition. Similarly, DAC C
and DAC D can be used for window detection on a second
V
IN
signal.
02066-039
V
DD
5V
GND
V
IN
PASS/FAIL
1/2
CMP04
1/6 74HC05
FAIL
PASS
1kΩ
0.1μF
SCL
SDA
SCL
DIN
1kΩ
V
REF
1
ADDITIONAL PINS OMITTED FOR CLARITY
10μF
1/2
AD5306/
AD5316/
AD5326
1
V
REF
A
V
REF
B
V
OUT
B
V
OUT
A
Figure 39. Window Detection
COARSE AND FINE ADJUSTMENT USING THE
AD5306/AD5316/AD5326
Two of the DACs in the AD5306/AD5316/AD5326 can be
paired together to form a coarse and fine adjustment function,
as shown in
Figure 40. DAC A is used to provide the coarse
adjustment while DAC B provides the fine adjustment. Varying
the ratio of R1 and R2 changes the relative effect of the coarse
and fine adjustments. With the resistor values and external
reference shown, the output amplifier has unity gain for the
DAC A output; therefore, the output range is 0 V to 2.5 V − 1
LSB. For DAC B, the amplifier has a gain of 7.6 × 10
−3
, giving
DAC B a range of 19 mV. Similarly, DAC C and DAC D can be
paired together for coarse and fine adjustment.
The circuit in
Figure 40 is shown with a 2.5 V reference, but
reference voltages up to V
DD
may be used. The op amps
indicated allow a rail-to-rail output swing.
02066-040
1μF
V
REF
A
V
DD
GND
V
OUT
B
0.1μF
10μF
VOUT
V
IN
GND
EXT
REF
AD820/
OP295
5V
R3
51.2kΩ
R4
390Ω
AD780/REF192
W
ITH V
DD
= 5V
V
OUT
A
R1
390Ω
R2
51.2kΩ
V
OUT
V
DD
= 5V
1/2
AD5306/
AD5316/
AD5326
V
REF
B
Figure 40. Coarse/Fine Adjustment