MAX1776 查看數據表（PDF） - Maxim Integrated

零件编号

产品描述 (功能)

比赛名单

MAX1776

24V, 600mA Internal Switch, 100% Duty Cycle, Step-Down Converter

Maxim Integrated 

24V, 600mA Internal Switch, 100% Duty Cycle,

Step-Down Converter

D

CIN

SHDN

ILIM

ILIM

SET

ILIM2

QR

S

MAXIMUM

ON-TIME

DELAY

MINIIMUM

OFF-TIME

DELAY

Figure 2. Simplified Functional Diagram

LX WAVEFORM, CIRCUIT 1

VIN = 15V, ILOAD = 500mA

1A

IL

0

10V

VLX

0

VOUT

50mV/div

2µs/div

Figure 3. Discontinuous-Conduction Operation

MAX1776

LX

L1

D1

OUTPUT

COUT

OUT

FB

100mV

VSET

1.25V

GND

Input-Output (Dropout) Voltage

A step-down converter’s minimum input-to-output volt-

age differential (dropout voltage) determines the lowest

usable supply voltage. In battery-powered systems,

this limits the useful end-of-life battery voltage. To maxi-

mize battery life, the MAX1776 operates with duty

cycles up to 100%, which minimizes the dropout volt-

age and eliminates switching losses while in dropout.

When the supply voltage approaches the output volt-

age, the P-channel MOSFET remains on continuously to

supply the load.

Dropout voltage is defined as the difference between

the input and output voltages when the input is low

enough for the output to drop out of regulation. For a

step-down converter with 100% duty cycle, dropout

depends on the MOSFET drain-to-source on-resistance

and inductor series resistance; therefore, it is propor-

tional to the load current:

VDROPOUT = IOUT ✕ (RDS(ON) + RINDUCTOR)

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