DAC081C081 Datasheet, PDF (26/41 Pages) Texas Instruments – 8-Bit Micro Power Digital-to-Analog Converter

DAC081C081, DAC081C085
SNAS449E – FEBRUARY 2008 – REVISED JANUARY 2016
10 Power Supply Recommendations
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10.1 Using References as Power Supplies
While the simplicity of the DAC081C081 implies ease of use, it is important to recognize that the path from the
reference input (V_A for the DAC081C081 and V_REF for the DAC081C085) 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 DAC081C085, the supply pin (V_A) and V_REF can be
connected together and share the same supply voltage. Since the DAC081C081 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. Listed below are a few
reference and power supply options for the DAC081C081. When using the DAC081C081, it is important to treat
the analog supply (V_A) as the reference.
10.1.1 LM4132
The LM4132, with its 0.05% accuracy over temperature, is a good choice as a reference source for the
DAC081C081. The 4.096-V version is useful if a 0 to 4.095-V output range is desirable or acceptable. Bypassing
the LM4132 V_IN pin with a 0.1-µF capacitor and the V_OUT pin with a 2.2-µF capacitor will improve stability and
reduce output noise. The LM4132 comes in a space-saving 5-pin SOT23.
Input
Voltage
C1
0.1 PF
LM4132-4.1
C2
2.2 PF
C3
0.1 PF
V_A V_REF
DAC081C081/5 _{VOUT = 0V to 4.092V}
SDA
SCL
Figure 31. The LM4132 as a Power Supply
10.1.2 LM4050
Available with accuracy of 0.44%, the LM4050 shunt reference is also a good choice as a reference for the
DAC081C081. It is available in 4.096-V and 5-V versions and comes in a space-saving 3-pin SOT23.
Input
Voltage
R
V_Z
I_Z
LM4050-4.1
or
LM4050-5.0
I_DAC
0.47 PF
V_A V_REF
0.1 PF
DAC081C081/5 _{VOUT = 0V to 5V}
SDA
SCL
Figure 32. The LM4050 as a Power Supply
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