Datasheet

UG-324 Evaluation Board User Guide
Rev. 0 | Page 4 of 8
TEST CIRCUITS
The E VA L-AD5116EBZ incorporates several test circuits to
evaluate the AD5116 performance.
DAC
The AD5116 can be operated as a digital-to-analog converter
(DAC), as shown in Figure 2.
10202-002
BUF-W
750Ω
12Ω
V
DD
AC
DC
GND
AC
R9
W
A
B
A
W
B
R8
V
DD
2
V
DD
2
VOUT
Figure 2. DAC
Table 3 shows the options available for the voltage references.
Table 3. DAC Voltage References
Terminal Link Options Description
A
LK1
AC
Connects Terminal A to V
DD
/2
DC Connects Terminal A to V
DD
W BUF-W Connects Terminal W to an
output buffer
B LK6 AC Connects Terminal B to V
DD
/2
GND Connects Terminal B to
analog ground
The output voltage is defined in Equation 1.
256
)(
RDAC
VVV
B
A
OUT
×−=
(1)
where:
RDAC is the code loaded in the RDAC register.
V
A
is the voltage applied to Terminal A (LK1 link).
V
B
is the voltage applied to Terminal B (LK6 link).
However, by using the R8 and R9 external resistors, the user can
reduce the voltage of the voltage references. In this case, use the
A and B test points to measure the voltage applied to the A and
B terminals and recalculate V
A
and V
B
in Equation 1.
AC Signal Attenuation
The AD5116 can be used to attenuate an ac signal, which must
be provided externally using the AC_INPUT connector, as
shown in Figure 3.
10202-003
BUF-W
750Ω
f
C
= 200Hz
12Ω
VOUT
AC
AC_INPUT
GND
AC
R9
R7
W
A
B
A
W
B
R8
V
DD
2
V
DD
2
HPF
Figure 3. AC Signal Attenuator
Depending on the voltage supply rails and the dc offset voltage
of the ac signal, various configurations can be used as described
in Table 4.
Table 4. AC Signal Attenuation Link Options
Terminal Link Options Description
A LK1 AC Remove dc voltage and biased
the signal to V
DD
/2
W BUF-W Connects Terminal W to an
output buffer
B LK6 AC1 Connects Terminal B to V
DD
/2
GND Connects Terminal B to analog
ground
1
Recommended to ensure optimal total harmonic distortion (THD) performance.
The signal attenuation is defined in Equation 2.






×≈
128
log20)dB(
RDAC
nAttenuatio
(2)
where:
RDAC is the code loaded in the RDAC register.
In addition, R7 can be used to achieve an exponential attenua-
tion. To do so, adjust the R7 resistor until a desirable transfer
function is found, typically value is around 1.6 kΩ for a 10 kΩ
potentiometer.