Datasheet

LM4050-4.1
or
LM4050-5.0
DAC121S101
DIN
SCLK
SYNC
V
OUT
= 0V to 5V
0.47 PF
Input
Voltage
R
V
Z
LM4130-4.1
DAC121S101
DIN
SCLK
SYNC
V
OUT
= 0V to 4.095V
C1
0.1 PF
C2
2.2 PF
Input
Voltage
MICROWIRE
DEVICE
DAC121S101
CS
SK
SO
SCLK
DIN
SYNC
DAC121S101
SNAS265I –JUNE 2005–REVISED MARCH 2013 www.ti.com
Figure 40. Microwire Interface
USING REFERENCES AS POWER SUPPLIES
Recall the need for a quiet supply source for devices that use their power supply voltage as a reference voltage.
Since the DAC121S101 consumes very little power, a reference source may be used as the supply voltage. The
advantages of using a reference source over a voltage regulator are accuracy and stability. Some low noise
regulators can also be used for the power supply of the DAC121S101. Listed below are a few power supply
options for the DAC121S101.
LM4130
The LM4130 reference, with its 0.05% accuracy over temperature, is a good choice as a power source for the
DAC121S101. Its primary disadvantage is the lack of 3V and 5V versions. However, the 4.096V version is useful
if a 0 to 4.095V output range is desirable or acceptable. Bypassing the LM4130 VIN pin with a 0.1µF capacitor
and the VOUT pin with a 2.2µF capacitor will improve stability and reduce output noise. The LM4130 comes in a
space-saving 5-pin SOT23.
Figure 41. The LM4130 as a power supply
LM4050
Available with accuracy of 0.44%, the LM4050 shunt reference is also a good choice as a power regulator for the
DAC121S101. It does not come in a 3 Volt version, but 4.096V and 5V versions are available. It comes in a
space-saving 3-pin SOT23.
Figure 42. The LM4050 as a power supply
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