ADR395 AD [Analog Devices], ADR395 Datasheet - Page 29

• Manufacturer Part Number: ADR395
• Description: Complete Dual, 16-Bit, High Accuracy, Serial Input, Bipolar Voltage Output DACs
• Manufacturer: AD [Analog Devices]

Preliminary Technical Data
APPLICATIONS INFORMATION
TYPICAL OPERATING CIRCUIT
Figure 42 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. This leads to an overall savings
in both cost and board space.
In Figure 42, V
and V
Figure 42, AGNDA and AGNDB are connected to REFGND.
BIN/2sCOMP
Table 18. Some Precision References Recommended for Use with the AD5762R
Part No.
ADR435
ADR425
ADR02
ADR395
AD586
RSTOUT
RSTIN
SYNC
LDAC
SCLK
SDIN
SS
SDO
D0
D1
can operate with supplies from ±11.4 V to ±16.5 V. In
Initial Accuracy(mV Max)
±6
±6
±5
±6
±2.5
TEMP
DD
+5V
Figure 42. Typical Operating Circuit
and V
1
2
3
4
5
6
7
8
SCLK
SDO
CLR
LDAC
D0
D1
SYNC
SDIN
100nF
SS
10µF
are both connected to ±15 V, but V
32 31 30 29 28 27 26 25
9
+15V –15V
10µF
10 11 12 13 14 15 16
AD5762R
+5V
10µF
100nF
+15V –15V
Long-Term Drift (ppm Typ)
30
50
50
50
15
10µF
100nF
AGNDA
AGNDB
VOUTA
VOUTB
NC
NC
NC
NC
24
23
22
21
20
19
18
17
VOUTA
VOUTB
Rev. PrA | Page 29 of 33
DD
Temp Drift (ppm/°C Max)
3
3
3
25
10
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. Thought should be given to 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.
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 ad-
justment 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’s output voltage
affects INL, DNL, and TUE. A reference with a tight
temperature coefficient 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 needs to be considered.
Choosing a reference with as low an output noise voltage as
practical for the system resolution required is important.
Precision voltage references such as the ADR435 (XFET design)
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.
0.1 Hz to 10 Hz Noise (µV p-p Typ)
3.4
3.4
15
5
4
AD5762R