Rainbow Electronics MAX5133 - Manual (Page 16)

MAX5132/MAX5133
+5V/+3V, 13-Bit, Serial, Force/Sense DACs
with 10ppm/°C Internal Reference
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where NB is the numeric value of the DAC’s binary
input code, V
REF is the voltage of the internal (or exter-
nal) precision reference, and G is the overall gain. The
application circuit in Figure 10 uses a low-cost op amp
(MAX4162) external to the MAX5132/MAX5133.
Together with the MAX5132/MAX5133, this circuit offers
an overall gain of 2V/V. Table 6 lists example codes for
bipolar output voltages.
Reset (RSTVAL) and
Clear (
C CLLR R) Functions
The MAX5132/MAX5133 DACs feature a clear pin
(CLR), which resets the output to a certain value,
depending upon how RSTVAL is set. RSTVAL = DGND
selects an output of 0, and RSTVAL = V
DD selects a
midscale output when CLR is pulled low.
The CLR pin has a minimum input resistance of 40k
Ω
in
series with a diode to the supply voltage (V DD ). If the
digital voltage is higher than the supply voltage for the
part, a small input current may flow, but this current will
be limited to (V
CLR - V DD - 0.5V) / 40k
Ω
.
Note: Clearing the DAC will also cause the part to exit
software shutdown (PD = 0).
Daisy-Chaining Devices
Any number of MAX5132/MAX5133s may be daisy-
chained simply by connecting the serial data output pin
(DOUT) of one device to the serial data input pin (DIN)
of the following device in the chain (Figure 11).
Another configuration (Figure 12) allows several
MAX5132/MAX5133 DACs to share one common DIN
signal line. In this configuration, the data bus is com-
mon to all devices; data is not shifted through a daisy
chain. However, more I/O lines are required in this con-
figuration because each IC needs a dedicated CS line.
MAX5132
MAX5133
DAC
GAIN = 2 V/V
REF
FB
OUT
DGND AGND
+5V/+3V
V DD
50k
50k
Figure 9. Unipolar Output Circuit Using Internal (+1.25V/+2.5V)
or External Reference. With external reference, pull REFADJ
to V
DD .
Figure 10. Unity-Gain Bipolar Output Circuit Using Internal
(+1.25V/+2.5V) or External Reference. With external reference,
pull REFADJ to V
DD .
AGND DGND
MAX5132
MAX5133
DAC
REF
FB
OUT
50k 50k
V-
V+
V DD
V OUT
+5V/+3V
MAX4162
TO OTHER
SERIAL DEVICES
MAX5132
MAX5133
DIN
SCLK
CS
MAX5132
MAX5133 MAX5132
MAX5133
DIN DOUT DOUT DOUT
SCLK
CS
I II III
DIN
SCLK
CS
Figure 11. Daisy-Chaining Multiple Devices with the Digital I/Os DIN/DOUT