LT3487
Boost and Inverting
Switching Regulator
for CCD Bias
U
DESCRIPTIO
FEATURES
ThG LT®3487 duaꢀ chaeeGꢀ swiꢃchieg ꢂGguꢀaꢃꢄꢂ gGeGꢂaꢃGs
ꢆꢄsiꢃivG aed eGgaꢃivG ꢄuꢃꢆuꢃs ꢅꢄꢂ biasieg CCD iAagGꢂs.
ThG dGvicG dGꢀivGꢂs uꢆ ꢃꢄ –8V aꢃ 90Aꢇ aed 15V aꢃ 45Aꢇ
ꢅꢂꢄA a ꢀiꢃhiuA-iꢄe cGꢀꢀ, ꢆꢂꢄvidieg bias ꢅꢄꢂ Aaey ꢆꢄꢆuꢀaꢂ
CCD iAagGꢂs. ThG bꢄꢄsꢃ ꢂGguꢀaꢃꢄꢂ iecꢄꢂꢆꢄꢂaꢃGs ꢄuꢃꢆuꢃ
discꢄeeGcꢃ ꢃGcheꢄꢀꢄgy ꢃꢄ GꢀiAieaꢃG ꢃhG DC cuꢂꢂGeꢃ ꢆaꢃh
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Generates 15V at 45mA, –8V at 90mA from a
Li-Ion Cell
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Output Disconnect
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Sequencing: Positive Output Reaches Regulation
Before Negative Channel Begins Switching
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Internal Schottky Diodes
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ꢅꢂꢄA V ꢃꢄ ꢃhG ꢄuꢃꢆuꢃ ꢀꢄad ꢃhaꢃ is ꢆꢂGsGeꢃ ie sꢃaedaꢂd
2MHz Constant Switching Frequency
IN
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bꢄꢄsꢃ cꢄefiguꢂaꢃiꢄes. ThG 2MHz swiꢃchieg ꢅꢂGquGecy
aꢀꢀꢄws CCD sꢄꢀuꢃiꢄes usieg ꢃiey, ꢀꢄw ꢆꢂꢄfiꢀG caꢆaciꢃꢄꢂs
aed ieducꢃꢄꢂs aed gGeGꢂaꢃGs ꢀꢄw eꢄisG ꢄuꢃꢆuꢃs ꢃhaꢃ aꢂG
Gasy ꢃꢄ fiꢀꢃGꢂ. Schꢄꢃꢃky diꢄdGs aꢂG ieꢃGꢂeaꢀ aed ꢃhG ꢄuꢃꢆuꢃ
vꢄꢀꢃagGs aꢂG sGꢃ wiꢃh ꢄeG ꢂGsisꢃꢄꢂ ꢆGꢂ chaeeGꢀ, ꢂGducieg
ꢃhG GxꢃGꢂeaꢀ cꢄAꢆꢄeGeꢃ cꢄueꢃ.
Requires Only One Resistor per Channel to Set
Output Voltages
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V ±aegG: 2.3V ꢃꢄ 16V
IN
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■
■
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Ouꢃꢆuꢃ VꢄꢀꢃagG Uꢆ ꢃꢄ 28V
Shꢄꢂꢃ-Ciꢂcuiꢃ ±ꢄbusꢃ
Caꢆaciꢃꢄꢂ PꢂꢄgꢂaAAabꢀG Sꢄꢅꢃ-Sꢃaꢂꢃ
SGꢆaꢂaꢃG V Pie ꢇꢀꢀꢄws SGꢆaꢂaꢃG SꢄuꢂcGs ꢅꢄꢂ
BꢇT
IeꢃGꢀꢀigGeꢃ sꢄꢅꢃ-sꢃaꢂꢃ aꢀꢀꢄws sGquGeꢃiaꢀ sꢄꢅꢃ-sꢃaꢂꢃ ꢄꢅ ꢃhG ꢃwꢄ
chaeeGꢀswiꢃhasiegꢀGcaꢆaciꢃꢄꢂ.ThGsꢄꢅꢃ-sꢃaꢂꢃissGquGecGd
such ꢃhaꢃ ꢃhG ꢄuꢃꢆuꢃ ꢂaAꢆ ꢄꢅ ꢃhG eGgaꢃivG chaeeGꢀ bGgies
aꢅꢃGꢂꢃhGꢂaAꢆꢄꢅꢃhGꢆꢄsiꢃivGchaeeGꢀ. IeꢃGꢂeaꢀsGquGecieg
ciꢂcuiꢃꢂyaꢀsꢄdisabꢀGsꢃhGeGgaꢃivGchaeeGꢀueꢃiꢀꢃhGꢆꢄsiꢃivG
chaeeGꢀ has ꢂGachGd 87% ꢄꢅ iꢃs fieaꢀ vaꢀuG, Gesuꢂieg ꢃhaꢃ
ꢃhG suA ꢄꢅ ꢃhG ꢃwꢄ ꢄuꢃꢆuꢃs is aꢀways ꢆꢄsiꢃivG.
PꢄwGꢂ aed Cꢄeꢃꢂꢄꢀ Ciꢂcuiꢃꢂy
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ꢇvaiꢀabꢀG ie 10-LUGad (3AA × 3AA) DFN PackagG
APPLICATIO S
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CCD Bias
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TFT LCD Bias
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OLED Bias
ThG LT3487 is avaiꢀabꢀG ie a 10-ꢆie 3AA × 3AA DFN
ꢆackagG.
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±±aiꢀ ꢁGeGꢂaꢃiꢄe ꢅꢄꢂ Oꢆ ꢇAꢆs
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
U
TYPICAL APPLICATIO
Conversion Efficiency
15µH
10µH
80
POS CHANNEL AT CAP
75
2.2µF
SWN
V
SWP
CAP
BAT
V
IN
3V TO 12V
70
V
POS CHANNEL
IN
65
AT V
POS
1µF
549k
100nF
LT3487
NEG CHANNEL
60
55
DN
FBP
47pF
4.7µF
15µH
50
45
40
V
NEG
FBN
–8V
324k
RUN/SS
V
POS
90mA
15V
RUN/SS
V
POS
V
= 3.6V
IN
45mA
GND
22µF
100nF
20
40
LOAD CURRENT (mA)
80
0
100
60
3487 TA01a
3487 TA01b
3487f
1