2
Figure 4 shows the preferred way to connect a CMOS
MDAC for a 0 to +10V output. This approach is less
expensive and provides better accuracy than the other ap-
proaches shown below.
The circuit shown in Figure 5 is commonly used to get a
0 to +10V output with a CMOS MDAC. The disadvantage
with this circuit is that it requires an extra op amp and
pair of precision resistors for each DAC. Also, settling
time increases because two amplifiers must settle in the
signal path. For good settling time, both amplifiers must be
fast settling. Then settling time increases by the square-
root-of-the-sum-of-the-squares of settling time for each
amplifier.
The circuit shown in Figure 6 can also be used to get a 0
to +10V output from a CMOS MDAC. The problem with
this circuit is nonlinearity due to code-dependent voltage
across the switches within the DAC. Using a 2.5V reference
and gain at the output, as shown, mitigates this error, but
you still need a pair of precision resistors for each DAC.
The appropriate use for this circuit is in +5V single-supply
applications. With a 2.5V reference and a unity-gain, single-
supply buffer, the output will be 0 to +2.5V.
FIGURE 4. Precision 0V to +10V Output DAC.
Figure 3 shows an improved filter and a provision for output
voltage adjustment. The 20k
pot can be used for fine
adjustments or to increase the output to –10.24V for 10mV
per 10-bit LSB—ideal in many binary DAC applications.
The improved filter:
1. Provides low output impedance at high frequency for
driving dynamic loads,
2. Improves noise filtering, and
3. Drives large capacitive loads—see AB-003.
The information provided herein is believed to be reliable; however, BURR-BROWN assumes no responsibility for inaccuracies or omissions. BURR-BROWN assumes
no responsibility for the use of this information, and all use of such information shall be entirely at the user’s own risk. Prices and specifications are subject to change
without notice. No patent rights or licenses to any of the circuits described herein are implied or granted to any third party. BURR-BROWN does not authorize or warrant
any BURR-BROWN product for use in life support devices and/or systems.
FIGURE 5. Another 0V to +10V Output DAC.
V+
+2.5V
Reference
+2.5V
Com
10k
0.01%
+V
S
V
REF
DAC7541A
Out 1
R
FB
0 to +10V
Out
Bit 1–Bit 12
0.01%
30k
FIGURE 6. Single Supply 0V to +10V.
V+
+10V
Reference
+10V
Com
10k
+V
S
V
REF
DAC7541A
Out 1
R
FB
0 to +10V
Out
Bit 1–Bit 12
0–1mA
10k
0.01%
10k
0.01%
V+
–10V
Reference
–10V
Com
10k
+V
S
V
REF
DAC7541A
Out 1
R
FB
0 to +10V
Out
Bit 1–Bit 12
0–1mA