MAX1763(2001) 데이터 시트보기 (PDF) - Maxim Integrated

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MAX1763
(Rev.:2001)

1.5A, Low-Noise, 1MHz, Step-Up DC-DC Converter

Maxim Integrated 

1.5A, Low-Noise, 1MHz, Step-Up

DC-DC Converter

OUT

ONA

ONB

REF

GND

CLK/SEL

FB

ISET

AIN

IC POWER

2.15V

UNDERVOLTAGE LOCKOUT

1.25V

ON

RDY

REFERENCE

REF

DUAL

MODE/

FB

CONTROLLER

POUT

STARTUP

EN OSCILLATOR Q

D

Q

P

LX

EN

1MHz

OSCILLATOR

EN

OSC

Q

N

MODE

FB ISET

PGND

0.938V

GAIN

BLOCK

MAX1763

AO

N

Figure 1. Functional Diagram

Table 1. Typical Available Output Current

NUMBER

OF CELLS

INPUT

VOLTAGE

(V)

OUTPUT

VOLTAGE

(V)

OUTPUT

CURRENT

(mA)

1 NiCd/NiMH

1.2

3.3

675

2.4

2 NiCd/NiMH

2.4

3.3

1500

5.0

950

1 Li+

2.7 (min)

3.3

1300

1 Li+

2.7 (min)

5.0

1100

3 NiCd/NiMH

3.6

5.0

1600

noise spectrum. See Table 1 for typical available output

current.

In its normal mode of operation (CLK/SEL = low), the

MAX1763 offers fixed-frequency PWM operation

through most of its load range. At light loads (less than

25% of full load), the device automatically optimizes

efficiency by switching only as needed to supply the

load. Shutdown reduces quiescent current to just 1µA.

Figure 2 shows the standard application circuit for the

MAX1763. (An external Schottky diode is needed for

output voltages greater than 4V, or to assist low-voltage

startup.)

C3

0.22µF

VIN

0.7V TO 5.5V

L1

1.5µH

CLK/SEL

LX

ONA

POUT

MAX1763

ONB

OUT

AIN

ISET

REF

PGND

AO

FB

GND

C1

47µF

MBR0520L

D1

R5

4.7Ω

OUT

3.3V

C4

2 x 100µF

C2

1.0µF

NOTE: HEAVY LINES INDICATE HIGH-CURRENT PATHS.

Figure 2. PFM/PWM Automode Connection

Additional features include synchronous rectification for

high efficiency and increased battery life, and a gain

block that can be used to build a linear regulator using

an external P-channel MOSFET pass device. This gain

_______________________________________________________________________________________ 9

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