LTC3528_15 Datasheet, PDF (1/18 Pages) Linear Technology – 1A, 1MHz Synchronous Step-Up DC/DC Converters

LTC3528/LTC3528B
1A, 1MHz Synchronous
Step-Up DC/DC Converters
in 3mm × 2mm DFN
FEATURES
■ _{Delivers 3.3V at 200mA from a Single Alkaline/}
NiMH Cell or 3.3V at 400mA from Two Cells
■ _{VIN Start-Up Voltage: 700mV}
■ _{1.6V to 5.25V VOUT Range}
■ _{Up to 94% Efficiency}
■ _{Output Disconnect}
■ _{1MHz Fixed Frequency Operation}
■ _{VIN > VOUT Operation}
■ _{Integrated Soft-Start}
■ _{Current Mode Control with Internal Compensation}
■ _{Burst Mode}^® _{Operation with 12µA Quiescent Current}
(LTC3528)
■ _{Low Noise PWM Operation (LTC3528B)}
■ _{Internal Synchronous Rectifier}
■ _{Logic Controlled Shutdown: <1µA}
■ _{Anti-Ringing Control}
■ _{Low Profile (3mm × 2mm × 0.75mm) DFN Package}
APPLICATIONS
■ _{Medical Instruments}
■ _{Flash-Based MP3 Players}
■ _{Noise Canceling Headphones}
■ _{Wireless Mice}
■ _{Bluetooth Headsets}
DESCRIPTION
The LTC^®3528/LTC3528B are synchronous, fixed frequency
step-up DC/DC converters with output disconnect. High
efficiency synchronous rectification, in addition to a 700mV
start-up voltage and operation down to 500mV once
started, provides longer run time for single or multiple
cell battery-powered products.
A switching frequency of 1MHz minimizes solution
footprint by allowing the use of tiny, low profile induc-
tors and ceramic capacitors. The current mode PWM is
internally compensated, simplifying the design process.
The LTC3528 enters Burst Mode operation at light loads,
while the LTC3528B features continuous switching at light
loads. Anti-ringing circuitry reduces EMI by damping the
inductor in discontinuous mode. Additional features include
a low shutdown current, open-drain power good output,
short-circuit protection and thermal overload protection.
The LTC3528/LTC3528B are offered in an 8-lead 3mm ×
2mm × 0.75mm DFN package.
L, LT, LTC, LTM, Burst Mode, 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
4.7µH
V_IN
1.8V TO 3.2V
4.7µF
OFF ON
SW
V_IN
V_OUT
LTC3528
PGOOD FB
SHDN
GND
499k
287k
33pF
V_OUT
3.3V
400mA
10µF
3528 TA01a
Efficiency and Power Loss
100
V_OUT = 3.3V
90 ^{VIN = 2.4V}
80
EFFICIENCY
70
1000
100
10
60
1
POWER LOSS
50
0.1
40
30
0.01
0.1
1
10 100
LOAD CURRENT (mA)
0.01
1000
3528 TA01b
3528fd
1