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Monolithic Power Systems
Pin Description
Table 1: Pin Designators
#
Name Description
High-Side Gate Drive Boost Input. BS supplies the drive for the high-side n-channel MOSFET
1
BS
switch. Connect a 10nF 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 switches.
2
IN
Drive IN with a 4.75V to 28V power source. Bypass IN to GND with a suitably large capacitor
to eliminate noise on the input to the IC. See Input Capacitor section.
Power Switching Output. SW is the switching node that supplies power to the output.
3
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.
4
GND
Ground. (Note: Connect the exposed pad on backside to Pin 4).
Feedback Input. FB senses the output voltage to regulate that voltage. Drive FB with a
5
FB
resistive voltage divider from the output voltage. The feedback threshold is 1.222V. See
Setting the Output Voltage section.
Compensation Node. COMP is used to compensate the regulation control loop. Connect a
6
COMP
series RC network from COMP to GND to compensate the regulation control loop. In some
cases, an additional capacitor from COMP to GND is required. See Compensation section.
Enable Input. EN is a digital input that turns the regulator on or off. Drive EN high to turn on
the regulator, drive EN low to turn it off. An Under Voltage Lockout (UVLO) function can be
7
EN
implemented by the addition of a resistor divider from V
shutdown its needs to be less than 0.7V. For automatic startup, leave EN unconnected.
Soft Start Control Input. SS controls the soft start period. Connect a capacitor from SS to
8
SS
GND to set the soft-start period. A 0.1µF capacitor sets the soft-start period to 10ms. To
disable the soft-start feature, leave SS unconnected.
BS 1
IN
2
3
SW
GND
4
Exposed Pad on
Backside.
Connect to Pin 4.
MP1593
3A, 28V
Step Down Converter
PRELIMINARY
8
SS
7
EN
6
COMP
5
FB
to GND. For complete low current
IN
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