UG-473
Evaluation Board User Guide
Rev. 0 | Page 4 of 20
DIGITAL INTERFACE
The
EVAL-AD5141DBZ
can be configured as an I
2
C or SPI
digital interface, depending on the position in the A2 jumper
(see Table 4).
Table 4. Interface Selection
A2 Jumper Position
Digital Interface
A
SPI
B
I
2
C
If the part is configured in I
2
C mode, the A3 and A4 jumpers
select the I
2
C address (see Table 5).
Table 5. I
2
C Address Selection
A3 Jumper Position
A4 Jumper Position
Address
A
A
0101111
A
B
0100011
B
A
0101100
B
B
0100000
TEST CIRCUITS
The
EVAL-AD5141DBZ
and EVAL-MB-LV-SDZ incorporate
several test circuits to evaluate the performance of the
AD5141
.
DAC
The digiPOT can be operated as a digital-to-analog converter
(DAC), as shown in Figure 2. Table 6 and Figure 7 describe the
options available for the voltage references.
The output voltage is defined in Equation 1.
256
)
(
RDAC1
V
V
V
B
A
OUT
×
−
=
(1)
where:
RDAC1
is the code loaded in the RDAC1 register.
V
A
is the voltage applied to the A terminal (A9 link).
V
B
is the voltage applied to the B terminal (A10 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
A and B terminals and to recalculate V
A
and V
B
in Equation 1.
Table 6. DAC Voltage References Motherboard Links
Terminal
Link
Options
Description
A1
A9
AC+
Connects Terminal A1 to V
DD
/2
VDD
Connects Terminal A1 to V
DD
W1
BUF-W1
Connects Terminal W1 to an
output buffer
B1
A10
BIAS
Connects Terminal B1 to V
DD
/2
VSS
Connects Terminal B1 to V
SS
AGND
Connects Terminal B1 to
analog ground
Table 7. DAC Voltage References Daughter Board Links
Link
Options Description
A6
B
Connects Terminal A to A1
A7
B
Connects Terminal W to W1
A8
B
Connects Terminal B to B1
A1
IN
Closes feedback loop of second op amp
in the AD8618
1
1010-
002
VOUT1
R34
R35
A1
W1
RDAC
A
B
W
AC
AC+
AGND
BIAS
B1
VSS
V
SS
BUF-W1
AC_INPUT
1kHz
HPF
V
DD
2
V
DD
2
Figure 2. DAC
