LTC3412A
1
3412afb
APPLICATIO S
U
DESCRIPTIO
U
FEATURES
TYPICAL APPLICATIO
U
■ Point-of-Load Regulation
■ Notebook Computers
■ Portable Instruments
■ Distributed Power Systems
■ High Efficiency: Up to 95%
■
3A Output Current
■ Low Quiescent Current: 64
μA
■ Low RDS(ON) Internal Switch: 77mΩ
■
2.25V to 5.5V Input Voltage Range
■ Programmable Frequency: 300KHz to 4MHz
■
±2% Output Voltage Accuracy
■
0.8V Reference Allows Low Output Voltage
■ Selectable Forced Continuous/Burst Mode
operation
with Adjustable Burst Clamp
■
Synchronizable Switching Frequency
■ Low Dropout Operation: 100% Duty Cycle
■ Power Good Output Voltage Monitor
■
Overtemperature Protected
■ Available in 16-Lead Exposed Pad TSSOP and QFN
Packages
3A, 4MHz, Monolithic
Synchronous Step-Down Regulator
The LTC
3412A is a high efficiency monolithic synchro-
nous, step-down DC/DC converter utilizing a constant
frequency, current mode architecture. It operates from an
input voltage range of 2.25V to 5.5V and provides a
regulated output voltage from 0.8V to 5V while delivering
up to 3A of output current. The internal synchronous
power switch with 77m
Ω on-resistance increases effi-
ciency and eliminates the need for an external Schottky
diode. Switching frequency is set by an external resistor or
can be synchronized to an external clock. 100% duty cycle
provides low dropout operation extending battery life in
portable systems. OPTI-LOOP
compensation allows the
transient response to be optimized over a wide range of
loads and output capacitors.
The LTC3412A can be configured for either Burst Mode
operation or forced continuous operation. Forced continu-
ous operation reduces noise and RF interference while
Burst Mode operation provides high efficiency by reduc-
ing gate charge losses at light loads. In Burst Mode
operation, external control of the burst clamp level allows
the output voltage ripple to be adjusted according to the
application requirements.
3412A F01a
SYNC/MODE
VFB
PGOOD
SW
PGND
SGND
RT
RUN/SS
ITH
SVIN
PVIN
LTC3412A
294k
22
μF
COUT
100
μF
×2
0.47
μH
VOUT
2.5V AT 3A
VIN
3.3V
1000pF
2.2M
820pF
12.1k
115k
69.8k
392k
Efficiency and Power Loss
Figure 1. 2.5V/3A Step-Down Regulator
LOAD CURRENT (A)
0.01
EFFICIENCY
(%)
POWER
LOSS
(mW)
100
95
90
85
80
75
70
65
60
55
50
100000
10000
1000
100
10
1
0.1
1
10
!" ) .>
EFFICIENCY
POWER LOSS
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
Burst Mode and OPTI-LOOP are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
Protected by U.S. Patents, including 5481178, 6580258, 6304066, 6127815, 6498466,
6611131, 6724174.