The package of AX3484 is SOP-8L-EP; the pin assignment is given by:
( Top View )
High-Side Gate Drive Boost Input. BS supplies the drive for the high-side N-Channel
BS MOSFET switch. Connect a 0.01μF or greater capacitor from SW to BS to power the
high side switch.
Power Input. IN supplies the power to the IC, as well as the step-down converter
IN switches. Drive IN with a 4.75V to 23V power source. Bypass IN to GND with a suitably
large capacitor to eliminate noise on the input to the IC. See Input Capacitor.
Power Switching Output. SW is the switching node that supplies power to the output.
SW Connect the output LC filter from SW to the output load. Note that a capacitor is required
from SW to BS to power the high-side switch.
Feedback Input. FB senses the output voltage to regulate that voltage. Drive FB with a
FB resistive voltage divider from the output voltage. The feedback threshold is 0.925V. See
Setting the Output Voltage.
Compensation Node. COMP is used to compensate the regulation control loop. Connect
a series RC
GND to compensate the regulation control loop. In
from COMP to GND is required. See Compensation
Enable Input. EN is a digital input that turns the regulator on or off. Drive EN high to turn
EN on the regulator, drive it low to turn it off. Pull up with 100kΩ resistor for automatic
Soft-Start Control Input. SS controls the soft start period. Connect a capacitor from SS to
SS GND to set the soft-start period. A 0.1μF capacitor sets the soft-start period to 15ms. To
disable the soft-start feature, leave SS unconnected.
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Rev.1.1 Sep.05, 2011