Texas Instruments BUF20800, User Manual

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V
OUT
=
V V
1024
REFH REFL
-
?
Decimal Value of Code + V
REFL
V
OUT
=
15 0
1024
-
?
68 + 0 =
1020
1024
= 0.996
BUF20800/20820EVM Software Overview
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5.2.2 Measuring the Power Supply
You must measure the power supply (V
S
) with respect to the GND on the BUF20800/20820EVM board
and enter it in the V
SUP
field located in the top section of the software interface, as shown in Figure 18 .
Figure 18. Measuring and Entering Power-Supply Voltage
The voltage out of each DAC is calculated according to the V
REFH
and the V
REFL
scaled values entered.
These values exist as a window for maximum and minimum levels that the voltage can achieve. These
maximum and minimum levels are then multiplied by the decimal code to determine the DAC voltage. The
calculation is performed according to
Equation 3 .
(3)
For example, changing the value in the channel 6 cell, with V
REFH
and V
REFL
connected internally,
immediately changes the output of channel 6 to 0.996V.
Example: Channel 6: Code 44 (hexadecimal) = 68 (decimal)
5.2.3 Read DAC Button
By pressing the Read DAC button in the BUF20800/20820EVM software, all of the BUF20800/20820
DAC/V
COM
registers are read to obtain the respective current register contents. Once the read procedure is
complete, all of the corresponding text boxes are updated to show the current values present in the
DAC/V
COM
registers.
20 BUF20800/20820EVM User Guide and Software Tutorial SBOU100 – April 2011
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