max5523euat Maxim Integrated Products, Inc., max5523euat Datasheet - Page 18

• Manufacturer Part Number: max5523euat
• Description: Dual, Ultra-low-power, 10-bit, Voltage-output Dacs
• Manufacturer: Maxim Integrated Products, Inc.

See the circuit in
configure the MAX5524/MAX5525 to bias a current-out-
put transducer. In
MAX5524/MAX5525 is a function of the voltage drop
across the transducer added to the voltage drop
across the feedback resistor R.
Figure
figuration with unity gain. Table 4 lists the unipolar out-
put codes.
The MAX5524 output can be configured for bipolar
operation as shown in
given by the following equation:
where N
binary input code. Table 5 shows the digital codes (off-
set binary) and the corresponding output voltage for
the circuit in
The MAX5524/MAX5525 have force-sense outputs,
which provide a connection directly to the inverting ter-
minal of the output op amp, yielding the most flexibility.
The advantage of the force-sense output is that specific
gains can be set externally for a given application. The
gain error for the MAX5524/MAX5525 is specified in a
unity-gain configuration (op-amp output and inverting ter-
minals connected), and additional gain error results from
external resistor tolerances. Another advantage of the
force-sense DAC is that it allows many useful circuits to
be created with only a few simple external components.
Dual, Ultra-Low-Power,
10-Bit, Voltage-Output DACs
Figure
18
REFIN
______________________________________________________________________________________
6. Unipolar Output Circuit
6 shows the MAX5524 in a unipolar output con-
A
V
represents the decimal value of the DAC’s
MAX5524
OUT_
Figure
DAC
= V
Figure
Figure
7.
REFIN
Current-Output Transducer
Configurable Output Gain
Figure
5 for an illustration of how to
x [(N
5, the output voltage of the
7. The output voltage is
A
Voltage Biasing a
- 512) / 512]
Unipolar Output
V
N
(0 TO 1023 DECIMAL).
FB_
OUT
A
Bipolar Output
IS THE DAC INPUT CODE
=
OUT_
V
REFIN
1024
N
A
An example of a custom fixed gain using the MAX5524/
MAX5525 force-sense output is shown in
this example, R1 and R2 set the gain for V
where N
input code.
See the circuit in
use the MAX5525 to bias a two-electrode potentiostat
on the input of an ADC.
Bypass the power supply with a 4.7µF capacitor in parallel
with a 0.1µF capacitor to GND. Minimize lengths to reduce
lead inductance. If noise becomes an issue, use shielding
and/or ferrite beads to increase isolation. For the thin QFN
package, connect the exposed pad to ground.
Table 4. Unipolar Code Table (Gain = +1)
Table 5. Bipolar Code Table (Gain = +1)
MSB
1111
1000
1000
0111
0000
0000
MSB
1111
1000
1000
0111
0000
0000
V
OUTA
DAC CONTENTS
DAC CONTENTS
A
= [(V
1111
0000
0000
1111
0000
0000
represents the numeric value of the DAC
1111
0000
0000
1111
0000
0000
REFIN
Figure
1100
0100
0000
1100
0100
0000
LSB
1100
0100
0000
1100
0100
0000
LSB
Self-Biased Two-Electrode
x N
Bypassing Considerations
Potentiostat Application
A
10 for an illustration of how to
) / 1024] x [1 + (R2 / R1)]
+V
-V
REF
Power Supply and
ANALOG OUTPUT
REF
+V
ANALOG OUTPUT
+V
+V
+V
+V
(512/1024) = +V
-V
REF
+V
-V
REF
REF
(512/512) = -V
REF
REF
REF
REF
REF
(1023/1024)
(513/1024)
(511/1024)
0V
(511/512)
(511/512)
0V
(1/1024)
(1/512)
(1/512)
OUTA
Figure
.
REF
REF
8. In
/2