Datasheet

UG-348 EVAL-AD5162SDZ User Guide
Rev. 0 | Page 4 of 16
TEST CIRCUITS
The EVA L-AD5162SDZ incorporates several test circuits to
evaluate the AD5162 performance.
DAC
RDAC1 can be operated as a digital-to-analog converter (DAC),
as shown in Figure 2.
Figure 2. DAC
Table 4 shows the options available for the voltage references.
Table 4. DAC Voltage References
Terminal Link Options Description
A1 A20 AC + DC
Connects Terminal A1 to
(V
DD
− V
SS
)/2.
VDD Connects Terminal A1 to V
DD
.
W1 BUF_W1
Connects Terminal W1 to an
output buffer.
B1 A21 DC
Connects Terminal B1 to
(V
DD
− V
SS
)/2.
GND
Connects Terminal B1 to
analog ground.
The output voltage is defined in Equation 1.
256
)(
WB1
B1
A1
OUT
R
VVV ×−=
(1)
where:
R
WB1
is the resistor between the W1 and B1 terminals.
V
A1
is the voltage applied to the A1 terminal (A20 link).
V
B1
is the voltage applied to the B1 terminal (A21 link).
However, by using the R34 and R35 external resistors, the user
can reduce the voltage of the voltage references. In this case, use
the A1 and B1 test points to measure the voltage applied to the
A0 and B0 terminals and recalculate V
A0
and V
B0
in Equation 1.
AC Signal Attenuation
RDAC1 can be used to attenuate an ac signal, which must be
provided externally using the AC_INPUT connector, as shown
in Figure 3.
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 5.
Table 5. AC Signal Attenuation Link Options
Link Options Conditions
A20 AC + DC No dc offset voltage.
AC signal is outside the voltage supply rails
due to the dc offset voltage.
DC offset voltage ≠ V
DD
/2.
1
AC All other conditions.
A21 DC Use in conjunction with ac + dc link.
GND All other conditions.
1
Recommended to ensure optimal total harmonic distortion (THD) performance.
The signal attenuation is defined in Equation 2.








+
×=
−− ENDTOEND
WWB1
R
RR
nAttenuatio log20)dB(
(2)
where:
R
WB1
is the resistor between the W1 and B1 terminals.
R
W
is the wiper resistance.
R
END-TO-END
is the end-to-end resistance value.
In addition, R36 can be used to achieve a pseudologarithmic
attenuation. To do so, adjust the R36 resistor until a desirable
transfer function is found.
W1_BUF
A1
RDAC1
AC + DC
VDD
A1
B1
BUF_W1
GND
DC
2
V
DD
– V
SS
V
DD
2
V
DD
– V
SS
R34
R35
W1
W1
B1
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W1_BUF
A1
RDAC1
AC + DC
AC_INPUT
AC
A1
B1
BUF_W1
GND
2
V
DD
– V
SS
R34
R35
W1
W1
B1
1µF
R36
DC
2
V
DD
– V
SS
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