MP28252 – SYNCHRONOUS STEP-DOWN CONVERTER WITH INTERNAL MOSFETS

MP28252 Rev. 1.1

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4

12/25/2013

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PIN FUNCTIONS

Pin #

Name

Description

1

IN

Supply Voltage. The MP28252 operates from a +4.5V to +21V input rail. C1 is

needed to decouple the input rail. Use wide PCB trace to make the connection.

2, 3, 4, 5

SW

Switch Output. Use wide PCB trace to make the connection.

6

BST

Bootstrap. A capacitor connected between SW and BS pins is required to form a

floating supply across the high-side switch driver.

7

EN/SYNC

EN=1 to enable the chip. External clock can be applied to EN pin for changing

switching frequency. For automatic start-up, connect EN pin to VIN by proper EN

resistor divider as Figure 2 shows.

8

FB

Feedback. An external resistor divider from the output to GND, tapped to the FB

pin, sets the output voltage. To prevent current limit run away during a short

circuit fault condition the frequency fold-back comparator lowers the oscillator

frequency when the FB voltage is below 500mV.

9

PG

Power Good Output. The output of this pin is low if the output voltage is 15% less

than the normal value; otherwise it is an open drain.

10

VCC

Bias Supply. Decouple with 0.1μF~0.22μF cap. And the capacitance should be

no more than 0.22μF

11, 12, 13, 14

GND

System Ground. This pin is the reference ground of the regulated output voltage.

For this reason care must be taken in PCB layout. Suggested to be connected to

GND with copper and vias.

Exposed Pad

Exposed pad has no internal electrical connection, and make sure exposed pad

is connected to GND through a large copper area in PCB layout.