Analog Devices ADZS-21569-EZKIT, Руководство пользователя

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the board through software. The SoftConfig section of this manual serves as a reference to any user that intends to
modify an existing software example. If software provided by ADI is used, there should be little need to reference
this section.
NOTE: Care should be taken when changing SoftConfig settings not to create a conflict with interfaces. This is
especially true when connecting extender cards.
Overview of SoftConfig
In order to further clarify the use of electronic single FET switches and multi-channel bus switches, an example of
each is illustrated and compared to a traditional mechanical switching solution. This is a generic example that uses
similar FET and bus switch components that are on the board.
After this generic discussion there is a detailed explanation of the SoftConfig interface specific to the ADZS-21569-
EZKIT .
The Example of Individual FET Switches figure shows two individual FET switches (Pericom PI3A125CEX) with
reference designators
UA
and
UB
. Net names
ENABLE_A
and
ENABLE_B
control
UA
and
UB
. The default FET
switch enable settings in this example are controlled by resistors
RA
and
RB
which pull the enable pin 1 of
UA
and
UB
to ground (low). In a real example, these enable signals are controlled by the Microchip IO expander. The de-
fault pull-down resistors connects the signals
EXAMPLE_SIGNAL_A
and
EXAMPLE_SIGNAL_B
and also con-
nects signals
EXAMPLE_SIGNAL_C
and
EXAMPLE_SIGNAL_D
. To disconnect
EXAMPLE_SIGNAL_A
from
EXAMPLE_SIGNAL_B
, the Microchip IO expander is used to change
ENABLE_A
to a logic 1 through software
that interfaces with the Microchip. The same procedure for
ENABLE_B
disconnects
EXAMPLE_SIGNAL_C
from
EXAMPLE_SIGNAL_D
.
Figure 3-2:
Example of Individual FET Switches
Software-Controlled Switches (SoftConfig)
ADZS-21569-EZKIT Manual 3–3