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© 2011 Exar Corporation 4/16 Rev. 1.0.0
USING THE EVALUATION BOARD
INPUT VOLTAGE CONFIGURATION
The XRP7714EVB-DEMO-1 Board has several
different input voltage options. The Input
voltage components are rated at 35V. The
power components have been optimized for a
12V input rail. When running the board at an
input voltage other than 12V, use
PowerArchitect
TM
to evaluate the system
performance.
Single Wide Range, Input Voltage Rail
Both the XRP7714EVB-DEMO-1 and the
XRP7714EVB-DEMO-2P ship from the factory
configured for a single wide range input. The
Input voltage range is from 5.5V to 25V.
Single 5V Voltage Rail
Installing a zero ohm resistor into position R28
connects VIN to VCCA. This allows operation
down to 4.5V, but restricts the maximum input
voltage to 5.5V.
Dual Voltage Rail Operation
The XRP7714EVB-DEMO-x boards can be
configured to operate from two separate rails.
The following modifications must be made:
Remove 0 ohm resistors R2 and R13
Connect power for the XRP7714 between
pins VIN and GND
Connect channel power between pins VIN1
and GND
I
2
C INTERFACE
The XRP77XX family of controllers employs a
standard I2C interface. Pull-ups for the I2C
signals are not included on the demo board. If
using the demo board with something other
than the XRP77xxEVB-XCM, verify that the
SDA and SCL lines are pulled up.
Channel Design and Limitations
Channel 1 is designed to provide an output
voltage from 3.3V to 5.0V. The default voltage
is 3.3V.
Channel 2 is designed to provide an output
voltage from 1.8V to 2.5V. The default voltage
is 2.5V.
Channel 3 is designed to provide an output
voltage from 1.5V to 1.8V. The default
voltage is 1.8V.
Channel 4 is designed to provide an output
voltage from .9 to 1.2V. The default voltage is
1.0V. The Tantalum output capacitor is has a
4V rating. If modifying the channel 3 design,
do not exceed four volts unless the C45 is
replaced.
ENABLE PIN
The ENABLE pin connects to an RC network
This delays turn on of the device. It is pulled
up to AVDD with a 100K resistor and to
ground through a .01uFd capacitor. It appears
on pin 9 of connector CON5. This pin can be
used to turn on or turn off the device.
BOARD DIFFERENCES
The XRP7714EVB-DEMO-1 board is 2” x 2” and
does not have the facility for a power
connector.
The XRP7714EVB-DEMO-2 board is 2” x 2.5”
and comes from the factory with wired for
Single 5V operation. The Power Jack has been
removed from the board. Supplying more than
5V to the board will damage the XRP7714.
The XRP7714EVB-DEMO-2P board is 2” x 2.5”
and comes from the factory wired for a single
wide range input. The P denotes that a power
connector is installed for connection to a
power supply of the customers choosing. The
Center lead of the input connector is positive.
Operating the Evaluation Board
Note: The XRP7714EVB-DEMO-2, is designed
to be powered from the USB voltage that is
supplied to from the host PC. No additional
power connections are required to
demonstrate basic board functionality. If
connecting the board to an external power
source, Caution, Do not exceed 5.5V on the
chip, or it will be damaged.
Make sure that the board is configured for the
power supply(s) that you are using. Refer to
the Input Voltage Configuration section if you