LT3587
High Voltage Monolithic
Inverter and Dual Boost
FEATURES
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DESCRIPTION
The LT
®
3587 provides a one chip solution for applications
requiring two positive and one negative high voltage sup-
plies. The LT3587 input voltage range of 2.5V to 6V makes
it ideal for various battery-powered systems.
A single resistor programs each of the three output voltage
levels and the output current of Boost3. The intelligent soft-
start allows for sequential soft-start of the Boost1 output
followed by the negative output with a single capacitor.
Internal sequencing circuitry also disables the inverter until
the Boost1 output has reached 87% of its final value.
The LT3587 integrates all the power switches, soft-start,
and output-disconnect circuits into a small 3mm
×
3mm
QFN package. This high level of integration combined
with small external components makes the LT3587 ideal
for space constrained applications.
L,
LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
Ideal for CCD, LCD, LED Backlight and OLED
Applications
Easy Generation of 15V (50mA), –8V (100mA) and
20V (20mA) from a Li-Ion Cell
V
VIN
Range: 2.5V to 6V
Wide Output Ranges: Up to 32V for the Boosts and
Up to –32V for the Inverter
Output Disconnect for the Boost Channels
Boost3 Allows Voltage Programming and/or Current
Programming for a ‘One Wire Current Source’
Overload Fault Protection with Fault I/O Pin Indicator
Combined Soft-Start and Enable Pins
Small 20-Pin 3mm
×
3mm QFN Package
APPLICATIONS
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Digital Still and Video Cameras
Scanner and Display Systems
PDA, Cellular Phones and Handheld Computers
LED Backlight and OLED Display Drivers
CCD Imager Bias
General High Voltage Supply Bias
TYPICAL APPLICATION
Li-Ion Powered Supply for CCD Imager and Six White Backlight LEDs
V
VIN
2.5V TO 6V
1μF
2.2μF
SW3
CAP3
I
FB3
8.06k
GND
LT3587
EN/SS1
EN/SS3
FLT
SW2
2.2μF
V
VIN
2.5V TO 6V
15μH
15μH
22μF
CCD NEGATIVE
–8V, 100mA
3587 TA01a
10μH
15μH
90
VIN
SW1
CAP1
V
OUT1
FB1
10μF
CCD POSITIVE
15V, 50mA
EFFICIENCY (%)
1M
2.7pF
LED DRIVER
20mA, UP TO 6 LEDS
1M
6.8pF
Efficiency Curve
CDD
+
= 50mA
–
85 CDD = 100mA
LED = 20mA
80
75
70
65
60
55
50
0
0.5
1
NORMALIZED CURRENT
ALL CHANNELS
ENABLED
CDD
–
LED
POWER DISSIPATION
ALL CHANNELS
ENABLED
CDD
+
800
700
POWER DISSIPATION (mW)
600
500
400
300
200
100
0
1.5
3587 TA01b
V
OUT3
V
FB3
FB2
3587fc
1
LINER [ LINEAR TECHNOLOGY ]
