LTC3538 Datasheet, PDF (1/16 Pages) Linear Technology – 800mA Synchronous Buck-Boost DC/DC Converter

LTC3538
800mA Synchronous
Buck-Boost
DC/DC Converter
FEATURES
■ _{Regulated Output with Input Voltages Above,}
Below, or Equal to the Output
■ _{800mA Continuous Output Current from a Single}
Lithium-Ion/Polymer Cell
■ _{Single Inductor}
■ _{1.8V to 5.25V VOUT Range}
■ _{2.4V to 5.5V VIN Range}
■ _{1MHz Fixed Frequency Operation}
■ _{Output Disconnect in Shutdown}
■ _{35μA Quiesecent Current in Burst Mode Operation}
■ _{<5μA Shutdown Current}
■ _{Internal Soft-Start}
■ _{Small, Thermally Enhanced 8-Lead (2mm x 3mm)}
DFN package
APPLICATIONS
■ _{Miniature Hard Disk Drives}
■ _{MP3 Players}
■ _{Digital Cameras}
■ _{Cellular Handsets}
■ _{PDAs, Handheld PC}
■ _{GPS Receivers}
DESCRIPTION
The LTC^®3538 is a highly efficient, low noise, buck-boost
DC/DC converter that operates from input voltages above,
below, and equal to the output voltage. The topology
incorporated in the IC provides a continuous transfer
function through all operating modes, making the product
ideal for single Lithium Ion or multicell Alkaline or NiMH
applications where the output voltage is within the battery
voltage range.
The LTC3538 is suited for use in Micro Hard Disk Drive
(μHDD) applications with its 800mA current capability. Burst
Mode^® operation provides high efficiency at light loads.
The LTC3538 includes two 0.17Ω N-channel and two
0.2Ω P-channel MOSFET switches. Operating frequency
is internally set to 1MHz to minimize solution footprint
while maximizing efficiency.
Other features include <5μA shutdown current, internal
soft-start, short circuit protection and thermal shutdown.
The LTC3538 is available in a low profile (0.75mm), ther-
mally enhanced 8-lead (2mm × 3mm) DFN package.
, LT, LTC, LTM and Burst Mode are registered trademarks of Linear Technology
Corporation. All other trademarks are the property of their respective owners. Protected by
U.S. Patents including 5481178, 6304066, 6580258, 6166527, 6404251.
TYPICAL APPLICATION
V_IN
2.9V TO 4.2V
Li-Ion/Polymer to 3.3V at 800mA
L1
3.3μH
LTC3538
R1
SW1
SW2
464k
V_OUT
3.3V
800mA
10k
C_IN
10μF
PWM
V_IN
V_OUT
FB
BURST
BURST
V_C
GND
SD
ON OFF
33pF
C_OUT
22μF
15k
330pF
*
R2
200k
*μP OPEN DRAIN I/O
3538 TA01
Efficiency vs V_IN
100
V_OUT = 3.3V
I_LOAD = 200mA
95
90
85
80
2.4 2.9 3.4 3.9 4.4 4.9 5.4
V_IN (V)
3538 TA01b
3538fb
1