DAC8550_16 Datasheet, PDF (16/31 Pages) Texas Instruments – 16-bit, Ultra-Low Glitch, Voltage Output Digital-To-Analog Converter

DAC8550
SLAS476F – MARCH 2006 – REVISED MARCH 2016
www.ti.com
Feature Description (continued)
7.3.1.1 Resistor String
The resistor string section is shown in Figure 47. It is simply a string of resistors, each of value R. The code
loaded into the DAC register determines at which node on the string the voltage is tapped off to be fed into the
output amplifier by closing one of the switches connecting the string to the amplifier. Monotonicity is ensured
because of the string resistor architecture.
7.3.1.2 Output Amplifier
The output buffer amplifier is capable of generating rail-to-rail output voltages with a range of 0 V to V_DD. It is
capable of driving a load of 2 kΩ in parallel with 1000 pF to GND. The source and sink capabilities of the output
amplifier can be seen in the Typical Characteristics. The slew rate is 1.8 V/μs with a full-scale setting time of 8 μs
with the output unloaded.
The inverting input of the output amplifier is brought out to the V_FB pin. This architecture allows for better
accuracy in critical applications by tying the V_FB point and the amplifier output together directly at the load. Other
signal conditioning circuitry may also be connected between these points for specific applications.
R
R
R
To Output
Amplifier
R
R
Figure 47. Resistor String
7.3.2 Power-On Reset
The DAC8550 contains a power-on reset circuit that controls the output voltage during power-up. On power-up,
the output voltages are set to midscale; they remain that way until a valid write sequence is made to the DAC.
The power-on reset is useful in applications where it is important to know the state of the output of the DAC while
it is in the process of powering up.
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