Analog Devices EVAL-AD5142ADBZ User Manual page 5

Evaluation Board User Guide
AC Signal Attenuation
The RDAC can be used to attenuate an ac signal, which must be
provided externally using the AC_INPUT connector, as shown
in Figure 3.
Depending on the voltage supply rails and the dc offset voltage
of the ac signal, various configurations can be used as described
in Table 6.
The signal attenuation is defined in Equation 2.
= ×
Attenuatio n ( dB ) 20
where:
R is the wiper resistance.
W
R is the end-to-end resistance value.
AB
R is the resistor between the W1 and B1 terminals.
WB1
 
+
R R
 
WB1 W
log
 
R
 
AB
V
DD
1kHz
2
HPF
AC_INPUT
V
DD
2
V
SS
Figure 3. AC Signal Attenuator
Table 6. AC Signal Attenuation Link Options
Maximum
Voltage AC Signal
Supply Amplitude
Single V
DD
(2)
Dual V
DD
1 Recommended to ensure optimal total harmonic distortion (THD) performance.
AC+
AC
R34
A1
RDAC1
A1
W1
W1
BUF-W1
B1
B1
R35
BIAS
VSS
AGND
Rev. 0 | Page 5 of 20
Link Options
A9 AC+
AC
A10 BIAS
GND
/V A9 AC+
SS
AC
A10 GND
VSS
VOUT1
UG-472
Conditions
No dc offset voltage;
the ac signal is
outside the voltage
supply rails due to
the dc offset voltage;
or the dc offset
voltage ≠ V /2. 1
DD
All other conditions.
Use in conjunction
with the AC+ link.
All other conditions.
The ac signal is
outside the voltage
supply rails due to
the dc offset voltage;
the dc offset
voltage ≠ 0 V. 1
All other conditions.
Use in conjunction
with the AC+ link.
All other conditions.