DAC121S101_15 Datasheet, PDF (17/37 Pages) Texas Instruments – 12-Bit Micro Power, RRO Digital-to-Analog Converter

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Feature Description (continued)
V_A
R
R
R
DAC121S101, DAC121S101-Q1
SNAS265J – JUNE 2005 – REVISED SEPTEMBER 2015
To Output Amplifier
R
R
Figure 34. DAC Resistor String
8.3.3 Output Amplifier
The output buffer amplifier is a rail-to-rail type, providing an output voltage range of 0 V to V_A. All amplifiers, even
rail-to-rail types, exhibit a loss of linearity as the output approaches the supply rails (0 V and V_A, in this case). For
this reason, linearity is specified over less than the full output range of the DAC. The output capabilities of the
amplifier are described in the Electrical Characteristics.
8.4 Device Functional Modes
8.4.1 Power-On Reset
The power-on reset circuit controls the output voltage during power-up. Upon application of power the DAC
register is filled with zeros and the output voltage is 0 V and remains there until a valid write sequence is made to
the DAC.
8.4.2 Power-Down Modes
The DAC121S101 has four modes of operation. These modes are set with two bits (DB13 and DB12) in the
control register.
DB13
0
0
1
1
DB12
0
1
0
1
Table 1. Modes of Operation
OPERATING MODE
Normal Operation
Power-Down with 1kΩ to GND
Power-Down with 100kΩ to GND
Power-Down with Hi-Z
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