MP28258 – 3A, 4.2V-20V INPUT, FAST TRANSIENT SYNCHRONOUS STEP-DOWN CONVERTER IN QFN12 (2X3mm)

MP28258 Rev 1.14

www.MonolithicPower.com

8

9/25/2012

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© 2012 MPS. All Rights Reserved.

BLOCK DIAGRAM

START

-

+

+

-

+

SOFT

START/STOP

FREQ

VCC

5V LDO

ILIM

OC

Q

VCC

SW

GND

0

VCC

IN

BST

RSEN

LS

Driver

HS

Driver

LS_FET

HS_FET

PWM

LOGIC

xS

xR

Over-Current

Timer

Current Sense

Amplifer

Current

Modulator

UV

OV

UV Detect

Comparator

OV Detect

Comparator

OFF

Timer

ON

Timer

HS IIimit

Comparator

Loop

Comparator

EN

1.0V

0.8V

1MEG

0.4V

0

0

FB

PGOOD

Comparator

REFERENCE

PG

+

-

-

+

Figure 1—Function Block Diagram