XRP7664-65-74-75
2A/3A 18V Synchronous Step-Down Regulator, Constant frequency
(XRP7664-65), Light-Load efficiency (XRP7674-75)
© 2014 Exar Corporation
3/8
Rev. 2.0.0
USING THE EVALUATION BOARD
I
NITIAL
S
ETUP
Set the input supply to 12V and connect it to
VIN and GND connectors on the left side of the
evaluation board. Connect the load to the
VOUT and GND connectors at the right side of
the board. Check to make sure that jumper J1
is set to the left side (position marked
EN=VIN). The board will power up and
regulate the output at 3.3V upon turning on
the input supply. The XRP76XX should provide
nominal efficiency equal to figure 4 of the
datasheet.
J
UMPER
J1
FUNCTION
Jumper J1 can be used to either connect EN to
VIN or allow an independent logic-level control
signal to be applied to EN. The board is
supplied from EXAR with jumper set at left-
side (position marked EN=VIN). This allows for
automatic startup of the XRP76XX regulator
when VIN is applied.
SETTING THE OUTPUT VOLTAGE
Use an external resistor divider to set the
output voltage. Program the output voltage
from:
1
2
0.925
1
Where:
R1 is the resistor between V
OUT
and FB
R2 is the resistor between FB and GND
(nominally 10kΩ)
0.925V is the nominal feedback voltage.
