MP2116 –2A, 6V, 100% DUTY CYCLE SYNCHROOUS STEP-DOWN CONVERTER WITH 0.5A LDO

MP2116 Rev.1.0

www.MonolithicPower.com

9

1/17/2013

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OPERATION

IN1

FB1

FB2

GND

IN2

OUT2

PWROK

SW1

+

+

--

PWMCMP

PWM

OSC

+

--

EAMP1

ICS

0.6V

FB1/2

0.66V

OUT_Hi

EAO2

OUT_Lo

BIAS

&

VOLTAGE

REFERENCE

1.25MHz

OSCILLATOR

IAMP

10X

CURRENT

SENSE

AMP

DH

DL

+

--

MAIN

SWITCH

(PCH)

SYNCHRONOUS

RECTIFIER

(NCH)

+

--

POWER ON RESET

WINDOW

COMPARATORS

NO

GOOD

--

+

0.54V

--

+

Figure1―MP2116 Functional Block Diagramm

The MP2116 is a 1.25MHz current mode 2A

synchronous step-down switcher plus a low input

0.5A low dropout (LDO) linear regulator (see

Figure1). The MP2116 is optimized for low

voltage, Li-Ion battery powered applications

where high efficiency and small size are critical.

The MP2116 uses an external resistor divider to

set both the switcher and LDO output voltage

from 0.6V to 6V.

2A Synchronous Step-Down Switcher

The switcher integrates both a main switch and a

synchronous

rectifier,

which

provides

high

efficiency and eliminates an external Schottky

diode.

The duty cycle D of a step-down switcher is

defined as:

%

100

V

V

%

100

f

T

D

IN

OUT

OSC

ON

×

≈

×

×

=

the oscillator frequency (1.25MHz).