Test Circuits - Analog Devices EVAL-AD5142ADBZ User Manual

UG-472

TEST CIRCUITS

The EVAL-AD5142ADBZ and EVAL-MB-LV-SDZ incorporate
several test circuits to evaluate the performance of the AD5142A.
DAC
The digiPOT can be operated as a digital-to-analog converter
(DAC), as shown in Figure 2. Table 5 describes the options
available for the voltage references.
The output voltage is defined in Equation 1.
RDAC1
= − ×
V ( V V )
OUT A B
256
where:
RDAC1 is the code loaded in the RDAC1 register.
V is the voltage applied to the A terminal (A9 link).
A
V is the voltage applied to the B terminal (A10 link).
B
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
Table 5. DAC Voltage References
Terminal
A1
W1
(1)
B1
AC+
V
DD
2
VDD
V
DD
R34
A1
RDAC1
A1
W1
W1
BUF-W1
B1
B1
R35
BIAS
V
DD
2
VSS
V
SS
AGND
Figure 2. DAC
Rev. 0 | Page 4 of 20
Evaluation Board User Guide
A
Link Options Description
A9 AC+ Connects Terminal A1 to V
VDD Connects Terminal A1 to V
BUF-W1 Connects Terminal W1 to an
output buffer
A10 BIAS Connects Terminal B1 to V
VSS Connects Terminal B1 to V
AGND Connects Terminal B1 to
analog ground
VOUT1
and V in Equation 1.
B
/2
DD
DD
/2
DD
SS