Datasheet

LM4132-4.1
DAC101C081/5
SDA
SCL
V
OUT
= 0V to 4.092V
C1
0.1 PF
C2
2.2 PF
Input
Voltage
V
REF
C3
0.1 PF
V
A
DAC101C081, DAC101C081Q, DAC101C085
SNVS801A –APRIL 2012–REVISED MARCH 2013 www.ti.com
APPLICATIONS INFORMATION
USING REFERENCES AS POWER SUPPLIES
While the simplicity of the DAC101C081 implies ease of use, it is important to recognize that the path from the
reference input (V
A
for the DAC101C081 & V
REF
for the DAC101C085) to V
OUT
will have essentially zero Power
Supply Rejection Ratio (PSRR). Therefore, it is necessary to provide a noise-free supply voltage to the
reference. In order to use the full dynamic range of the DAC101C085, the supply pin (V
A
) and V
REF
can be
connected together and share the same supply voltage. Since the DAC101C081 consumes very little power, a
reference source may be used as the supply voltage.
(2)
The advantages of using a reference source over a
voltage regulator are accuracy and stability. Some low noise regulators can also be used. Listed below are a few
reference and power supply options for the DAC101C081. When using the DAC101C081, it is important to treat
the analog supply (V
A
) as the reference.
LM4132
The LM4132, with its 0.05% accuracy over temperature, is a good choice as a reference source for the
DAC101C081. The 4.096V version is useful if a 0 to 4.095V output range is desirable or acceptable. Bypassing
the LM4132 V
IN
pin with a 0.1µF capacitor and the V
OUT
pin with a 2.2µF capacitor will improve stability and
reduce output noise. The LM4132 comes in a space-saving 5-pin SOT-23.
Figure 30. The LM4132 as a Power Supply
(2) To ensure accuracy, it is required that V
A
and V
REF
be well bypassed.
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