MP28248 – 3A, 4.2V-20V INPUT, FAST-TRANSIENT SYNCHRONOUS STEP-DOWN CONVERTER IN QFN12 (2X3mm)

MP28248 Rev 1.0

www.MonolithicPower.com

10

1/5/2012

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© 2012 MPS. All Rights Reserved.

BLOCK DIAGRAM

FREQ

OC

BST

VCC

UV Detect

Comparator

-

+

5V LDO

0.4V

ILIM

UV

OV

HS-FET

1MEG

LS-FET

RSEN

VCC

OV Detect

Comparator

+

-

1.0V

PWM

AGND

LOGIC

OFF

Timer

Current

Modulator

BSTREG

SOFT

START/STOP

Loop

Comparator

-

+

+

xS

xR

HS

Driver

Q

Current Sense

Amplifer

SW

LS

Driver

GND

EN

IN

REFERENCE

0.8V

START

FB

Refresh

Timer

SS

HS Ilimit

Comparator

-

+

ON

Timer

Over-Current

Timer

Figure 1: Functional Block Diagram