MP2233 – SYNCHRONOUS, STEP-DOWN CONVERTER WITH INTERNAL MOSFETS

MP2233 Rev. 1.01

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8

12/6/2012

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PIN FUNCTIONS

Package

Pin #

Name

Description

1

SS

Soft-Start. Connect an external capacitor to program the soft-start time for the switch-

mode regulator.

2

IN

Supply Voltage. The IN pin supplies power for the internal MOSFET and regulator. The

MP2233 operates from a +4.5V to +16V input rail. Requires a low-ESR, and low-

inductance capacitor (C1) to decouple the input rail. Place the input capacitor very close

to this pin and connect it with wide PCB traces and multiple vias.

3

SW

through the high-side switch during the PWM duty cycle ON-time. The inductor current

drives the SW pin negative during the OFF-time. The ON-resistance of the low-side

switch and the internal body diode fixes the negative voltage. Connect using wide PCB

traces and multiple vias.

4

GND

System Ground. The regulated output voltage reference ground. Connect with copper

and vias.

5

BST

Bootstrap. Connect a capacitor between SW and BST pins to form a floating supply

across the high-side switch driver.

6

EN/SYNC

Enable. EN=high to enable the MP2233. Apply an external clock to change the switching

7

VCC

Internal 5V LDO Output. Powers the driver and control circuits. Decouple with 0.1μF-to-

0.22μF capacitor. Avoid capacitor values greater than 0.22μF.

8

FB

Feedback. Connect to the tap of an external resistor divider from the output to GND to set

the output voltage. The comparator lowers the oscillator frequency linearly with FB

voltage. For best results, place the resistor divider as close to the FB pin as possible.

Avoid placing vias on the FB traces.