LTC3560_15 Datasheet, PDF (1/16 Pages) Linear Technology – 2.25MHz, 800mA Synchronous Step-Down Regulator in ThinSOT

FEATURES
n _{High Efficiency: Up to 95%}
n _{Low Output Ripple (<20mVP-P): Burst Mode}^®
Operation: I_Q = 16μA
n _{2.5V to 5.5V Input Voltage Range}
n _{2.25MHz Constant Frequency Operation}
n _{Synchronizable to External Clock}
n _{No Schottky Diode Required}
n _{Stable with Ceramic Capacitors}
n _{Low Dropout Operation: 100% Duty Cycle}
n _{0.6V Reference Allows Low Output Voltages}
n _{Shutdown Mode Draws < 1μA Supply Current}
n _{±2% Output Voltage Accuracy}
n _{Current Mode Operation for Excellent Line and}
Load Transient Response
n _{Overtemperature Protected}
n _{Low Profile (1mm) ThinSOT™ Package}
APPLICATIONS
n _{Cellular Telephones}
n _{Wireless and DSL Modems}
n _{Digital Still Cameras}
n _{Media Players}
n _{Portable Instruments}
LTC3560
2.25MHz, 800mA
Synchronous Step-Down
Regulator in ThinSOT
DESCRIPTION
The LTC^®3560 is a high efficiency monolithic synchronous
buck regulator using a constant frequency, current mode
architecture. Supply current during operation is only 16μA,
dropping to <1μA in shutdown. The 2.5V to 5.5V input
voltage range makes the LTC3560 ideally suited for single
Li-Ion/Li-Polymer battery-powered applications. 100%
duty cycle provides low dropout operation, extending
battery life in portable systems.
Switching frequency is internally set at 2.25MHz, allowing
the use of small surface mount inductors and capacitors.
For noise sensitive applications the LTC3560 can be ex-
ternally synchronized from 1MHz to 3MHz. Burst Mode
operation is inhibited during synchronization or when the
SYNC/MODE pin is pulled high, preventing low frequency
ripple from interfering with audio circuitry.
The internal synchronous switch increases efficiency
and eliminates the need for an external Schottky diode.
Low output voltages are easily supported with the 0.6V
feedback reference voltage. The LTC3560 is available in a
low profile (1mm) ThinSOT package.
L, LT, LTC, LTM and Burst Mode are registered trademarks of Linear Technology Corporation.
ThinSOT is a trademark of Linear Technology Corporation. All other trademarks are the property
of their respective owners. Protected by U.S. Patents including 6580258, 5481178, 5994885,
6304066, 6498466, 6611131.
TYPICAL APPLICATION
V_IN
2.7V
TO 5.5V
C_IN
10μF
CER
V_IN
SW
LTC3560
RUN
SYNC/MODE V_FB
GND
3405A F01a
2.2μH
10pF
806k
255k
V_OUT
2.5V
C_OUT
10μF
CER
Figure 1a. High Efficiency Step-Down Converter
100
1
90
80
0.1
70
60
50
0.01
40
30
20
10
0
0.1
0.001
V_IN = 3.6V
V_IN = 4.2V
V_IN = 5.5V
0.0001
1
10
100
1000
LOAD CURRENT (mA)
3560 F01b
Figure 1b. Efficiency vs Load Current
3560fb
1