DC590B Datasheet, PDF (4/13 Pages) Linear Technology – USB SERIAL CONTROLLER

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 590B
USB SERIAL CONTROLLER FOR LINEAR TECHNOLOGY QUICKEVAL™ DEMO BOARDS
CONNECTIONS TO THE DC590B
Figure 2 shows the connections to the DC590B. In
most cases DC590B and the demonstration circuit
under evaluation can operate from available USB
power, and thus require nothing more than a USB
connection to the host PC and a ribbon connect-
ing DC590B to the demo circuit under evaluation.
DC590B offers several other power options, de-
scribed below.
Isolated Supply Options
An LT3439 low-noise switching power supply pro-
vides isolated power to the demonstration circuit
under evaluation and to the isolation circuitry. This
is adequate in many cases, however an external
power supply is recommended to reduce the load
on the host computer’s USB port or to reduce
power supply noise in the circuit under test.
and an external supply between 2.7 and 5V must
be applied to the VCCA turret post.
The +5V turret is the digital supply for the isolated
portion of DC590B. Do not draw current from this
point
LED Indicators
Two LED indicators are provided. The “ISO PWR”
LED is lit when either the onboard switching
power supply is running or external power is ap-
plied to the isolated side of the board.
The “COMMAND” LED indicates that a command
has been sent to the board by the host PC and is
waiting to be executed. The LED may not appear
to be blinking in some cases, as the duty cycle
may be very short.
The LT3439 switching power supply is enabled by
default but may be disabled by moving jumper
JP5 (ISO, to the left) to the OFF position. This al-
lows the isolated side of the board and the dem-
onstration circuit under evaluation to be powered
separately. This is recommended when testing
precision components such as high resolution
ADCs and DACs. After moving JP5 ISO to the
OFF position, apply a clean, regulated power sup-
ply from 7v to 10V to the V+ and AGND turret
posts.
Isolated Digital Supply
The signal levels on the digital interface are de-
termined by the VCCA voltage. The onboard regu-
lator can be set to 5V, 3.3V, 2.7V by installing JP6
in the appropriate position (remove jumper for
2.7V.) Selecting EXT shuts the regulator down,
Jumper Summary
Some jumpers on the DC590 board are for future
use and MUST be left in the default positions.
JP1 – PROG – Microcontroller in-circuit program-
ming header, do NOT install jumper, make no con-
nections.
JP2 – MODE – do NOT install jumper, make no
connections.
JP3 – Watchdog enable - do NOT install jumper,
make no connections.
JP4 – EE – Jumper MUST be in the EN position.
JP5 – SW (right-hand side) MUST be in the ON
position. ISO (left-hand side) controls the isolated
supply. See Connections section.
JP6 – VCCA control. See Connections section.
4