AD5762R Analog Devices, AD5762R Datasheet - Page 28

• Manufacturer Part Number: AD5762R
• Description: Complete Dual, 16-Bit, High Accuracy, Serial Input, Bipolar Voltage Output DAC
• Manufacturer: Analog Devices

Specifications of AD5762R

• Resolution (bits): 16bit
• Dac Update Rate: 84.6kSPS
• Dac Settling Time: 8µs
• Max Pos Supply (v): +16.5V
• Single-supply: No
• Dac Type: Voltage Out
• Dac Input Format: Ser,SPI

AD5762R
APPLICATIONS INFORMATION
TYPICAL OPERATING CIRCUIT
Figure 43 shows the typical operating circuit for the AD5762R.
The only external components needed for this precision 16-bit
DAC are decoupling capacitors on the supply pins and reference
inputs, and an optional short-circuit current setting resistor.
Because the AD5762R incorporates a voltage reference and
reference buffers, it eliminates the need for an external bipolar
reference and associated buffers, resulting in an overall savings
in both cost and board space.
In Figure 43, AV
AV
In Figure 43, AGNDA and AGNDB are connected to REFGND.
Precision Voltage Reference Selection
To achieve the optimum performance from the AD5762R over
its full operating temperature range, an external voltage reference
must be used. Care must be taken in the selection of a precision
voltage reference. The voltage applied to the reference input is
used to provide a buffered positive and negative reference for the
DAC cores. Therefore, any error in the voltage reference is
reflected in the outputs of the device.
There are four possible sources of error to consider when choosing
a voltage reference for high accuracy applications: initial accuracy,
temperature coefficient of the output voltage, long term drift,
and output voltage noise.
Table 20. Some Precision References Recommended for Use with the AD5762R
Part No.
ADR435
ADR425
ADR02
ADR395
AD586
DD
and AV
SS
can operate with supplies from ±11.4 V to ±16.5 V.
DD
Initial Accuracy
(mV Maximum)
±6
±6
±5
±6
±2.5
and AV
SS
are both connected to ±15 V, but
Long-Term Drift
(ppm Typical)
30
50
50
50
15
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Initial accuracy error on the output voltage of an external refer-
ence could lead to a full-scale error in the DAC. Therefore, to
minimize these errors, a reference with low initial accuracy error
specification is preferred. Choosing a reference with an output
trim adjustment, such as the ADR425, allows a system designer
to trim system errors out by setting the reference voltage to a
voltage other than the nominal. The trim adjustment can also
be used at temperature to trim out any error.
Long-term drift is a measure of how much the reference output
voltage drifts over time. A reference with a tight long-term drift
specification ensures that the overall solution remains relatively
stable over its entire lifetime.
The temperature coefficient of a reference output voltage affects
INL, DNL, and TUE. A reference with a tight temperature coeffi-
cient specification should be chosen to reduce the dependence of
the DAC output voltage on ambient conditions.
In high accuracy applications, which have a relatively low noise
budget, reference output voltage noise must be considered. It is
important to choose a reference with as low an output noise
voltage as practical for the system resolution that is required.
Precision voltage references such as the
produce low output noise in the 0.1 Hz to 10 Hz region. However,
as the circuit bandwidth increases, filtering the output of the
reference may be required to minimize the output noise.
Temperature Drift
(ppm/°C Maximum)
3
3
3
25
10
0.1 Hz to 10 Hz Noise
(μV p-p Typical)
3.5
3.4
10
5
4
ADR435
Data Sheet
(XFET® design)