LTC3527-1_15 Datasheet, PDF (1/22 Pages) Linear Technology – Dual 800mA/400mA, 1.2MHz/2.2MHz Synchronous Step-Up DC/DC Converters

LTC3527/LTC3527-1
Dual 800mA/400mA,
1.2MHz/2.2MHz Synchronous
Step-Up DC/DC Converters
FEATURES
n _{Dual Synchronous Step-Up DC/DC Converters}
n _{Delivers 3.3V at 200mA/100mA from one Alkaline/}
NiMH Cell, or 3.3V at 400mA/200mA from Two Cells
n _{VIN Start-Up Voltage: 700mV}
n _{0.5V to 5V VIN Range After Start-Up}
n _{1.6V to 5.25V VOUT Range}
n _{Output Disconnect in Shutdown}
n _{VIN > VOUT Operation}
n _{1.2MHz or 2.2MHz Operation}
n _{Up to 94% Efficiency}
n _{12μA Quiescent Current in Burst Mode}^® _Operation
n _{Inrush Current Limiting and Soft-Start}
n _{Internal Synchronous Rectifiers}
n _{Logic-Controlled Shutdown (< 2μA)}
n _{Quick VOUT Discharge (LTC3527-1)}
n _{16-Lead, 0.75mm × 3mm × 3mm QFN Package}
APPLICATIONS
n _{MP3/Personal Media Players}
n _{Noise Canceling/Bluetooth Headsets}
n _{Wireless Mice}
n _{Portable Medical Instruments}
DESCRIPTION
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.
The LTC3527/LTC3527-1 limit inrush current during 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
operation or fixed frequency operation is selectable via the
MODE pin. Anti-ring circuitry reduces EMI in discontinuous
mode. This device also features thermal shutdown.
True output disconnect allows the output to be completely
open in shutdown. The LTC3527-1 actively discharges
V_OUT1 or V_OUT2 when its respective SHDN goes low. Qui-
escent current in shutdown is less than 2μA.
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
ThinSOT is a trademark of Linear Technology Corporation. All other trademarks are the
property of their respective owners.
TYPICAL APPLICATION
Two-Cell Alkaline to 3.3V/1.8V Synchronous Boost Converters
+ ^{1.6V to 3.2V}
V_IN
4.7μF
V_OUT
3.3V
150mA
4.7μF ^1.78M
1M
ON
OFF
ON
OFF
4.7μH
V_IN1 V_IN V_IN2
SW1
V_OUT1
15pF
LTC3527
SW2
V_OUT2
FB1
FB2
PGOOD1
SHDN1
PGOOD2
SHDN2
MODE GND F_SEL
4.7μH
15pF ^619k
1.21M
35271 TA01
V_OUT
1.8V
150mA
4.7μF
1.2MHz Efficiency and Power Loss
100
BURST
90 _EFFICIENCY
80
1000
100
70
60
10
50 FIXED
FREQUENCY
40
1
30
20
POWER
LOSS
0.1
10
BURST
0
V_IN = 2.4V
V_OUT1 = 3.3V
0.01
0.01 0.1
1
10 100 1000
LOAD CURRENT (mA)
35271 TA01b
35271fc
1