SP6686ER-L/TR 查看數據表（PDF） - Signal Processing Technologies

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SP6686ER-L/TR

400mA Buck/Boost Charge Pump LED Driver

Signal Processing Technologies 

FUNCTIONAL DIAGRAM

RSET 6

RSET

RSET BLOCK

+

-

{ } 1.26V

V= RSET x11.2kohms

RSET REF

BG REF

+

-

1.26V

RESISTOR

TAPS

50mV

1 MUX

2x1

0s

FB REF

FB 7

+

FB

- COM P

SGN 8

CLK

FB COMP

COUNTER

32 COUNT

CLR

ONE

SHOT

FLASH 4

FLASH=1, S=1, RSET REF

FLASH=0, S=0, 50mV

EN 5

VIN 1

135C ON

145C OFF

THERMAL FAULT

OVER TEMP COMP

2.4MHZ

CLK

MODE SWITCH

0 =1X

1=2X

CHARGE

PUMP

SWITCHES

C1

C2

VOUT

CLK

SET

DOMINANT

S

0

R

PGND

The SP6686 is a charge pump regulator

designed for converting a Li-Ion battery

voltage of 2.7V to 4.2V to drive a white LED

used in digital still camera Flash and Torch

applications. The SP6686 has two modes

of operation which are pin selectable for

either Flash or Torch. Flash mode is usually

used with a pulse of about 200 to 300

milliseconds to generate a high intensity

Flash. Torch can be used continuously at a

lower output current than Flash and is often

used for several seconds in a digital still

camera “movie” mode.

THEORY OF OPERATION

The SP6686 also has two modes of opera-

tion to control the output current, the 1X

mode and 2X mode. Operation begins after

the enable pin EN receives a logic high, the

bandgap reference wakes up after 200µsec,

and then SP6686 goes through a soft-start

mode designed to reduce inrush current.

The SP6686 starts in the 1X mode, which

acts like a linear regulator to control the

output current by continuously monitoring

the feedback pin FB. In 1X mode, if the

SP6686 auto detects a dropout condition,

which is when the FB pin is below the

Date: 03/10/06

SP6686 400mA, Buck/Boost Charge Pump LED Driver

8

© Copyright 2006 Sipex Corporation

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