max5290beudt Maxim Integrated Products, Inc., max5290beudt Datasheet - Page 30

• Manufacturer Part Number: max5290beudt
• Description: Buffered, Fast-settling, Dual, 12-/10-/8-bit, Voltage-output Dacs
• Manufacturer: Maxim Integrated Products, Inc.

Buffered, Fast-Settling, Dual, 12-/10-/8-Bit,
Voltage-Output DACs
Figure 7 shows the unity gain of the MAX5290 in a
unipolar output configuration. Table 24 lists the unipolar
output codes.
The MAX5290 outputs can be configured for bipolar
operation, as shown in Figure 8. The output voltage is
given by the following equation:
where CODE represents the numeric value of the
DAC’s binary input code (0 to 4095 decimal). Table 25
shows digital codes and the corresponding output volt-
age for the Figure 8 circuit.
Table 25. Bipolar Code Table (Gain = +1)
Figure 8. Bipolar Output Circuit
30
REF
MSB
1111
1000
1000
0111
0000
0000
______________________________________________________________________________________
DAC CONTENTS
V
MAX5290
OUT_
1111
0000
0000
1111
0000
0000
DAC_
Applications Information
= V
1111
0001
0000
1111
0001
0000
LSB
REF
x (CODE - 2048) / 2048
-V
REF
10kΩ
+V
ANALOG OUTPUT
-V
+V
+V
REF
(2048 / 2048) = -V
REF
Unipolar Output
OUT_
REF
REF
Bipolar Output
(2047 / 2048)
(2047 / 2048)
10kΩ
(1 / 2048)
(1 / 2048)
0
V+
V-
REF
V
OUT_
The MAX5291/MAX5293/MAX5295 have force-sense out-
puts, which provide a connection directly to the inverting
terminal 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 MAX5291/MAX5293/MAX5295 is speci-
fied in a unity-gain configuration (op-amp output and
inverting terminals connected) and additional gain error
results from external resistor tolerances. The force-sense
DACs allow many useful circuits to be created with only a
few simple external components.
An example of a custom, fixed gain using the
MAX5291’s force-sense output is shown in Figure 9. In
this example, the external reference is set to 1.25V, and
the gain is set to +1.1V/V with external discrete resis-
tors to provide an approximate 0 to 1.375V DAC output
voltage range.
where CODE represents the numeric value of the
DAC’s binary input code (0 to 4095 decimal).
In this example, if R2 = 12kΩ and R1 = 10kΩ, set the
gain = 1.1V/V:
Figure 9. Configurable Output Gain
V
OUT_
REF
V
OUT_
= [(0.5 x V
MAX5291
DAC_
= [(0.5 x 1.25V x CODE) / 4096] x 2.2
REF
x CODE) / 4096] x [1 + (R2 / R1)]
Configurable Output Gain
FB_
OUT_
R2 = 12kΩ
0.1%
25ppm
R1 = 10kΩ
0.1%
25ppm