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参数资料
| 型号： | SP7685EB |
| 厂商： | Exar Corporation |
| 文件页数： | 4/12页 |
| 文件大小： | 0K |
| 描述： | EVAL BOARD FOR SP7665 |
| 标准包装： | 1 |
| 系列： | * |
FUNCTIONAL DIAGRAM
{ }
RSET 6
RSET BLOCK
+
-
RSET
R SET
R SET REF= x 14 μ A
5
BG REF
+
- 1.26V
RSET REF
RESISTOR
TAPS
1
MUX
2x1
50mV 0 s
FB REF
FB 7
SGND 8
+
FB
COM P
-
FB COMP
ONE
SHOT
CLK
COUNTER
32 COUNT
CLR
SET
DOMINANT
S
0
R
FLASH 4
FLASH=1, S=1, RSET REF
EN 5
FLASH=0, S=0, 50mV
VIN 1
MODE SWITCH
0 =1X
1=2X
135C ON
THERMAL FAULT
145C OFF
2.4MH Z
OVER TEMP COMP
CLK
CHARGE
PUMP
SWITCHES
C1
C2
VOUT
CLK
PGND
THEORY OF OPERATION
The SP7685 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 SP7685 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.
The SP7685 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 200 μ s,
and then SP7685 goes through a soft-start
mode designed to reduce inrush current.
The SP7685 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
SP7685 auto detects a dropout condition,
which is when the FB pin is below the
regulation point for more than 32 cycles of
the internal clock, the SP7685 automati-
cally switches to the 2X mode. The SP7685
remains in the 2X mode until one of four
things happens: 1) the enable pin EN has
been toggled, 2) the Flash pin has changed
from high to low, 3) V IN is cycled or, 4) a
thermal fault occurs.
The 2X mode is the charge pump mode
where the output can be pumped as high as
two times the input voltage, provided the
output does not exceed the maximum volt-
age for the SP7685, which is internally
limited to about 5.5V. In the 2X mode, as in
the 1X mode, the output current is regulated
by the voltage at the FB pin.
Date: 6/20/06 Rev T
SP7685, 1.2A Buck/BoostCharge Pump LED Driver
4
? 2006 Sipex Corporation
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相关代理商/技术参数 |
参数描述 |
|---|---|
| SP7685ER | 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:Evaluation Board Manual |
| SP7685ER-L | 功能描述:LED照明驱动器 1.2A Bck/Bst Charge Pump LED Driver RoHS:否 制造商:STMicroelectronics 输入电压:11.5 V to 23 V 工作频率: 最大电源电流:1.7 mA 输出电流: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:SO-16N |
| SP7685ER-L/TR | 功能描述:LED照明驱动器 1.2A BUCK/BOOST LED DRVR RoHS:否 制造商:STMicroelectronics 输入电压:11.5 V to 23 V 工作频率: 最大电源电流:1.7 mA 输出电流: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:SO-16N |
| SP7686 | 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:Constant Current Flash Driver in DFN 2mm x 3mm |
| SP7686A | 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:Constant Current Flash Driver in DFN 2mm x 3mm |
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