EVAL-AD5764REBZ View Datasheet(PDF) - Analog Devices
Part Name
Description
MFG CO.
EVAL-AD5764REBZ
Analog Devices
'EVAL-AD5764REBZ' PDF : 32 Pages View PDF
AD5764R
Preliminary Technical Data
APPLICATIONS INFORMATION
TYPICAL OPERATING CIRCUIT
Figure 39 shows the typical operating circuit for the AD5764R.
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 AD5764R 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 39, VDD and VSS are both connected to ±15 V, but VDD
and VSS can operate with supplies from ±11.4 V to ±16.5 V. In
Figure 39, AGNDA is connected to REFGND.
+15V –15V
10µF
100nF
10µF
100nF
BIN/2sCOMP
SYNC
SCLK
SDIN
SDO
LDAC
D0
D1
TEMP
+5V
32 31 30 29 28 27 26 25
1 SYNC
2 SCLK
3 SDIN
4 SDO
5 CLR
6 LDAC
7 D0
8 D1
AD5764R
AGNDA 24
VOUTA 23
VOUTB 22
AGNDB 21
AGNDC 20
VOUTC 19
VOUTD 18
AGNDD 17
VOUTA
VOUTB
VOUTC
VOUTD
RSTOUT
RSTIN
9 10 11 12 13 14 15 16
10µF
100nF
10µF
+5V
+15V –15V
Figure 39. Typical Operating Circuit
Precision Voltage Reference Selection
To achieve the optimum performance from the AD5764R 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 AD5764R has two
reference inputs, REFAB and REFCD. The voltages applied to
the reference inputs are 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.
Table 18. Some Precision References Recommended for Use with the AD5764R
Part No. Initial Accuracy(mV Max) Long-Term Drift (ppm Typ) Temp Drift (ppm/°C Max)
ADR435 ±6
30
3
ADR425 ±6
50
3
ADR02 ±5
50
3
ADR395 ±6
50
25
AD586 ±2.5
15
10
0.1 Hz to 10 Hz Noise (μV p-p Typ)
3.4
3.4
15
5
4
Rev. PrA | Page 28 of 32
Share Link: 