LTC3527/LTC3527-1
Dual 800mA/400mA,
1.2MHz/2.2MHz Synchronous
Step-Up DC/DC Converters
DESCRIPTION
FEATURES
The LTC®3527/LTC3527-1 are dual high efficiency,
step-up DC/DC converters in a space saving 16-lead 3mm
× 3mm QFN package. Battery life is maximized with a
700mV start-up voltage and operation down to 500mV
once started. The SHDN and PGOOD pins enable the
converters to be sequenced or started together.
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Dual Synchronous Step-Up DC/DC Converters
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Delivers 3.3V at 200mA/100mA from one Alkaline/
NiMH Cell, or 3.3V at 400mA/200mA from Two Cells
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V Start-Up Voltage: 700mV
IN
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0.5V to 5V V Range after Start-Up
IN
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1.6V to 5.25V V
Range
OUT
■
■
■
■
■
■
■
■
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Output Disconnect in Shutdown
TheLTC3527/LTC3527-1limitinrushcurrentduring start-
up. Selectable 1.2MHz or 2.2MHz operation provides a
choice between the highest efficiency or smallest solu-
tion footprint. The current mode PWM design is internally
compensated reducing external parts count. Burst Mode
operationorfixedfrequencyoperationisselectableviathe
MODEpin.Anti-ringcircuitryreducesEMIindiscontinuous
mode. This device also features thermal shutdown.
V > V
Operation
IN
OUT
1.2MHz or 2.2MHz Operation
Up to 94% Efficiency
12µA Quiescent Current in Burst Mode® Operation
Inrush Current Limiting and Soft-Start
Internal Synchronous Rectifiers
Logic-Controlled Shutdown (< 2µA)
Quick V
Discharge (LTC3527-1)
OUT
True output disconnect allows the output to be completely
open in shutdown. The LTC3527-1 actively discharges
16-Lead, 0.75mm × 3mm × 3mm QFN Package
V
or V
when its respective SHDN goes low. Qui-
OUT1
OUT2
APPLICATIONS
escent current in shutdown is less than 2µA.
, LT, LTC, LTM and Burst Mode are registered trademarks of Linear Technology
Corporation. All other trademarks are the property of their respective owners.
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MP3/Personal Media Players
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Noise Canceling/Bluetooth Headsets
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Wireless Mice
Portable Medical Instruments
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TYPICAL APPLICATION
Two-Cell Alkaline to 3.3V/1.8V Synchronous Boost Converters
1.2MHz Efficiency and Power Loss
100
90
80
70
60
50
40
30
20
10
0
1000
1.6V to 3.2V
BURST
+
EFFICIENCY
V
IN
4.7µF
100
10
4.7µH
4.7µH
V
V
V
IN2
IN1
IN
V
V
OUT
1.8V
150mA
SW1
OUT1
SW2
OUT2
OUT
V
V
FIXED
FREQUENCY
3.3V
150mA
619k
1.78M
LTC3527
1
4.7µF
FB1
FB2
POWER
LOSS
1.21M
0.1
0.01
1M
PGOOD1
SHDN1
PGOOD2
SHDN2
ON
ON
V
V
= 2.4V
OUT1
IN
4.7µF
= 3.3V
BURST
OFF
MODE GND
F
SEL
0.01
0.1
1
10
100
1000
LOAD CURRENT (mA)
35271 TA01b
35271 TA01
OFF
35271f
1