Datasheet

DIN
SCLK
SYNC
V
OUT
0.1 PF
+
10 PF
+
-
R
1
R
2
+5V
R
3
(= R
1
)
R
A
R
B
Load
I
O
LMV710
V
REF
DAC088S085
DAC088S085
www.ti.com SNAS424C –AUGUST 2007–REVISED MARCH 2013
Table 5. Some Rail-to-Rail Amplifiers
AMP PKGS Typ V
OS
Typ I
SUPPLY
LMP7701 SOT-23 ±37 µV 0.79 mA
LMV841 SOT-23 −17 µV 1.11 mA
LMC7111 SOT-23 900 µV 25 µA
LM7301 SOT-23 30 µV 620 µA
LM8261 SOT-23 700 µV 1 mA
VARIABLE CURRENT SOURCE OUTPUT
The DAC088S085 is a voltage output DAC but can be easily converted to a current output with the addition of an
opamp. In Figure 37, one of the channels of the DAC088S085 is converted to a variable current source capable
of sourcing up to 40mA.
Figure 37. Variable Current Source
The output current of this circuit (I
O
) for any DAC code is found to be
I
O
= (V
REF
x (D / 256) x (R
2
) / (R
1
x R
B
) (8)
where D is the input code in decimal form and R
2
= R
A
+ R
B
.
APPLICATION CIRCUITS
The following figures are examples of the DAC088S085 in typical application circuits. These circuits are basic
and will generally require modification for specific circumstances.
Industrial Application
Figure 38 shows the DAC088S085 controlling several different circuits in an industrial setting. Channel A is
shown providing the reference voltage to the ADC081S625, one of Texas Instruments general purpose Analog-
to-Digital Converters (ADCs). The reference for the ADC121S625 may be set to any voltage from 0.2V to 5.5V,
providing the widest dynamic range possible. Typically, the ADC121S625 will be monitoring a sensor and would
benefit from the ADC's reference voltage being adjustable. Channel B is providing the drive or supply voltage for
a sensor. By having the sensor supply voltage adjustable, the output of the sensor can be optimized to the input
level of the ADC monitoring it. Channel C is defined to adjust the offset or gain of an amplifier stage in the
system. Channel D is configured with an opamp to provide an adjustable current source. Being able to convert
one of the eight channels of the DAC088S085 to a current output eliminates the need for a separate current
output DAC to be added to the circuit. Channel E, in conjunction with an opamp, provides a bipolar output swing
for devices requiring control voltages that are centered around ground. Channel F and G are used to set the
upper and lower limits for a range detector. Channel H is reserved for providing voltage control or acting as a
voltage setpoint.
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