MAX1760 查看數據表（PDF） - Maxim Integrated

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MAX1760

0.8A, Low-Noise, 1MHz, Step-Up DC-DC Converter

Maxim Integrated 

0.8A, Low-Noise, 1MHz,

Step-Up DC-DC Converter

OUT

IC POWER

UNDERVOLTAGE LOCKOUT

ON

(MAX1760H)

ON

(MAX1760)

REF

GND

2.15V

ON

RDY

REFERENCE

1.25V

REF GND

CLK/SEL

FB

ISET

MAX1760

STARTUP

EN OSCILLATOR Q

CONTROLLER

D

EN

OSC

OSCILLATOR

1MHz

CLK/SEL

MODE

EN

OSC

MODE

FB

ISET

POUT

PCH

LX

NCH

PGND

Figure 1. Functional Diagram

Detailed Description

The MAX1760 is a highly efficient, low-noise power sup-

ply for portable RF and hand-held instruments. It com-

bines a boost switching regulator, N-channel power

MOSFET, P-channel synchronous rectifier, precision

reference, and shutdown control (Figure 1).

The DC-DC converter boosts a 1-cell to 3-cell battery

voltage input to a fixed 3.3V or adjustable voltage

between 2.5V and 5.5V. An external Schottky diode is

required for output voltages greater than 4V. The

MAX1760 guarantees startup with an input voltage as

low as 1.1V and remains operational down to an input

of just 0.7V. It is optimized for use in cellular phones

and other applications requiring low noise and low qui-

escent current for maximum battery life. It features

fixed-frequency operation at medium and heavy loads,

but at light loads, switches only as needed for optimum

efficiency. This device is also capable of constant-fre-

quency (1MHz), low-noise PWM operation at all load

currents, or frequency-synchronized PWM operation

when connected to an external clock. Table 1 lists

some typical outputs. Shutdown reduces quiescent cur-

rent to just 1µA. Figure 2 shows the standard applica-

tion circuit for the MAX1760.

VIN = 2.4V

3.3µH

33µF

ON

CLK/SEL

LX

0.22µF

MAX1760

POUT

ISET

REF

OUT

FB GND PGND

VOUT = 3.3V,

800mA

4.7Ω

100µF

0.68µF

Figure 2. Standard Application Circuit

Step-Up Converter

During DC-DC converter operation, the internal N-chan-

nel MOSFET switch turns on for the first part of each

cycle, allowing current to ramp up in the inductor and

store energy in a magnetic field. During the second

part of each cycle, the MOSFET turns off and inductor

current flows through the synchronous rectifier to the

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