DC590B Datasheet, PDF (9/13 Pages) Linear Technology – USB SERIAL CONTROLLER

APPENDIX A
APPENDIX A: DC590A CONNECTIONS AND SCHEMATIC
This section shows the schematic and connec-
tions to DC590A, which DC590B replaces. The
only functional difference between DC590A and
DC590B is that the digital signals on DC590B can
be adjusted from 2.7 to 5V, where the DC590A is
5V only.
DC590B also offers improved isolation, as all 14
conductors on the 14 pin interface header are iso-
lated from the PC’s ground.
Figure 3 shows how to connect an external supply
to the isolated side of the controller and the board
under evaluation. After disabling the switching
supply by placing JP1 in the OFF position, apply
7V–9V between the GND and V+ posts. These
posts are the in, out, and ground terminals of an
LT1761 LDO regulator. The demonstration circuit
under evaluation may draw up to 100mA from
V_CC.
7V
REGULATED
SUPPLY
DEMONSTRATION
CIRCUIT
UNDER
EVALUATION
14-CONDUCTOR
RIBBON
CABLE
USB CABLE
TO HOST PC
Figure 3. Connecting an external supply to the isolated side of the controller
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