Datasheet
AD5063
Rev. C | Page 16 of 20
APPLICATIONS
Table 7. Recommended Precision References for the AD5063
Part No.
Initial
Accuracy
(mV max)
Temperature Drift
(ppm/°C max)
CHOOSING A REFERENCE FOR THE AD5063
To achieve optimum performance of the AD5063, thought
should be given to the choice of a precision voltage reference.
The AD5063 has one reference input, V
REF
. The voltage on the
reference input is used to supply the positive input to the DAC;
therefore, any error in the reference is reflected in the DAC.
0.1 Hz to 10 Hz
Noise (μV p-p typ)
ADR435 ±2 3 (R-8) 8
ADR425 ±2 3 (R-8) 3.4
ADR02 ±3 3 (R-8)
10
ADR02 ±3 3 (SC-70)
10
There are four possible sources of error when choosing a voltage
reference for high accuracy applications: initial accuracy, ppm
drift, long-term drift, and output voltage noise. Initial accuracy
on the output voltage of the DAC leads to a full-scale error in the
DAC. To minimize these errors, a reference with high initial
accuracy is preferred. Also, choosing a reference with an output
trim adjustment, such as the ADR423, allows a system designer to
trim out system errors by setting a reference voltage to a voltage
other than the nominal. The trim adjustment can also be used at
any point within the operating temperature range to trim out error.
ADR395 ±5 9 (TSOT-23) 8
BIPOLAR OPERATION USING THE AD5063
The AD5063 has been designed for single-supply operation, but
a bipolar output range is also possible by using the circuit shown
in Figure 37. This circuit yields an output voltage range of ±4.096 V.
Rail-to-rail operation at the amplifier output is achievable using
AD8675/AD8031/AD8032 or an OP196.
The output voltage for any input code can be calculated as
Because the supply current required by the AD5063 is extremely
low, the parts are ideal for low supply applications. The ADR395
voltage reference is recommended; it requires less than 100 μA of
quiescent current and can, therefore, drive multiple DACs in one
system, if required. It also provides very good noise performance
at 8 μV p-p in the 0.1 Hz to 10 Hz range.
⎥
⎦
⎤
⎢
⎣
⎡
⎟
⎠
⎞
⎜
⎝
⎛
×−
⎟
⎠
⎞
⎜
⎝
⎛
+
×
⎟
⎠
⎞
⎜
⎝
⎛
×=
R1
R2
V
R1
R2R1D
VV
DDDD
O
536,65
where D represents the input code in decimal (0 to 65,536).
With V
REF
= 5 V, R1 = R2 = 30 kΩ
AD5063
3-WIRE
SERIAL
INTERFACE
SYNC
SCLK
DIN
7V
5V
V
OUT
= 0V TO 5V
ADR395
04766-036
V5
65536
10
−
⎟
⎠
⎞
⎜
⎝
⎛
×
=
D
V
O
This is an output voltage range of ±5 V, with 0x0000 corresponding
to a −5 V output and 0xFFFF corresponding to a +5 V output.
04766-037
AD5063
DACGND
VV
REF
DD
OUT
SCLK
DIN
SYNC
+5V
+4.096
V
EXTERNAL
OP A
MP
BIPOLAR
OUTPUT
10
µ
F
SERIAL
INTERFACE
0.1
µ
F
0.1
µ
F
INV
R
INV
+5V
–5V
R
FB
R
FB
AGND
+
Figure 36. ADR395 as a Reference to AD5063
Long-term drift is a measure of how much the reference drifts
over time. A reference with a tight long-term drift specification
ensures that the overall solution remains relatively stable during
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 temperature dependence of the DAC output voltage
on ambient conditions.
Figure 37. Bipolar Operation
In high accuracy applications, which have a relatively low
tolerance for noise, reference output voltage noise needs to be
considered. It is important to choose a reference with as low an
output noise voltage as practical for the system noise resolution
required. Precision voltage references, such as the ADR435,
produce low output noise in the 0.1 Hz to 10 Hz region. Exam-
ples of some recommended precision references for use as the
supply to the AD5063 are shown in Table 7.