MAX8607 データシートの表示（PDF） - Maxim Integrated

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MAX8607

1MHz PWM Boost Converter for 1.5A White LED Camera Flash

Maxim Integrated 

1MHz PWM Boost Converter for 1.5A

White LED Camera Flash

LX

PGND

COMP

1MHz

CLOCK

REF

FORCED-PWM

BOOST CONTROL

OUT

OUTS

FEEDBACK

SELECT

1.25V

EN1

EN2

FLSH

MOV

GND

SHUTDOWN AND

MODE CONTROL

MAX8607

LDO

REGULATOR

LED

LGND

Figure 1. Functional Diagram

Detailed Description

Boost Converter

The MAX8607 includes a fixed-frequency, PWM boost

converter that supplies the LED current. The output

voltage is adaptively controlled to provide adequate

headroom with varying LED forward voltage. The boost

converter switches an internal power MOSFET and syn-

chronous rectifier at a constant 1MHz frequency with

varying duty cycle up to 75% to maintain constant LED

current over the 2.7V to 5.5V input range. Internal spe-

cial circuits prevent any unwanted subharmonic switch-

ing in the critical buck/boost region.

LDO Current Regulator (LED)

A low-dropout (LDO) linear current regulator from LED

to LGND sinks current from the external LED’s cathode

terminal. The LED current is regulated to a user-pro-

grammable level. In movie mode, the current into LED

is regulated to 1200 times the current set by the MOV

resistor (RMOV). In flash mode, the current into LED is

regulated to 5000 times the current set by the FLSH

resistor (RFLSH). In disco mode, the current into LED is

regulated to 80mA.

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