LTC3411_15 Datasheet, PDF (1/24 Pages) Linear Technology – 1.25A, 4MHz, Synchronous Step-Down DC/DC Converter

FEATURES
n _{Small 10-Lead MSOP or DFN Package}
n _{Uses Tiny Capacitors and Inductor}
n _{High Frequency Operation: Up to 4MHz}
n _{High Switch Current: 1.6A}
n _{Low RDS(ON) Internal Switches: 0.110Ω}
n _{High Efficiency: Up to 95%}
n _{Stable with Ceramic Capacitors}
n _{Current Mode Operation for Excellent Line}
and Load Transient Response
n _{Short-Circuit Protected}
n _{Low Dropout Operation: 100% Duty Cycle}
n _{Low Shutdown Current: IQ ≤ 1μA}
n _{Low Quiescent Current: 60μA}
n _{Output Voltages from 0.8V to 5V}
n _{Selectable Burst Mode}^® _Operation
n _{Synchronizable to External Clock}
APPLICATIONS
n _{Notebook Computers}
n _{Digital Cameras}
n _{Cellular Phones}
n _{Handheld Instruments}
n _{Board Mounted Power Supplies}
LTC3411
1.25A, 4MHz, Synchronous
Step-Down DC/DC Converter
DESCRIPTION
The LTC^®3411 is a constant frequency, synchronous,
step- down DC/DC converter. Intended for medium power
applications, it operates from a 2.63V to 5.5V input voltage
range and has a user configurable operating frequency
up to 4MHz, allowing the use of tiny, low cost capacitors
and inductors 2mm or less in height. The output voltage
is adjustable from 0.8V to 5V. Internal sychronous 0.11Ω
power switches with 1.6A peak current ratings provide
high efficiency. The LTC3411’s current mode architecture
and external compensation allow the transient response
to be optimized over a wide range of loads and output
capacitors.
The LTC3411 can be configured for automatic power sav-
ing Burst Mode operation to reduce gate charge losses
when the load current drops below the level required for
continuous operation. For reduced noise and RF interfer-
ence, the SYNC/MODE pin can be configured to skip pulses
or provide forced continuous operation.
To further maximize battery life, the P-channel MOSFET
is turned on continuously in dropout (100% duty cycle)
with a low quiescent current of 60μA. In shutdown, the
device draws <1μA.
L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
Burst Mode is a registered trademark of Linear Technology Corporation.
TYPICAL APPLICATION
13k
1000pF
V_IN
2.63V TO 5.5V
V_IN SYNC/MODE
PV_IN
PGOOD
SV_IN
SW
LTC3411
I_TH
SHDN/R_T
SGND
V_FB
PGND
324k
C1
22μF
L1
2.2μH
887k
412k
V_OUT
2.5V/1.25A
C2
22μF
NOTE: IN DROPOUT, THE OUTPUT TRACKS
THE INPUT VOLTAGE
C1, C2: TAIYO YUDEN JMK325BJ226MM
L1: TOKO A914BYW-2R2M (D52LC SERIES)
3411 F01
Figure 1. Step-Down 2.5V/1.25A Regulator
Efficiency vs Load Current
100
95
90
85
80
V_IN = 3.3V
75 ^VOUT ^{= 2.5V}
f_O = 1MHz
Burst Mode OPERATION
70
1
10
100
LOAD CURRENT (mA)
1000
3411 TA01
3411fb
1