LTC3407AIDD Datasheet, PDF (1/16 Pages) Linear Integrated Systems – Dual Synchronous, 600mA, 1.5MHz Step-Down DC/DC Regulator

FEATURES
n _{High Efficiency: Up to 96%}
n _{Very Low Quiescent Current: Only 40μA}
n _{1.5MHz Constant Frequency Operation}
n _{High Switch Current: 1A on Each Channel}
n _{No Schottky Diodes Required}
n _{Low RDS(ON) Internal Switches: 0.35Ω}
n _{Current Mode Operation for Excellent Line}
and Load Transient Response
n _{Short-Circuit Protected}
n _{Low Dropout Operation: 100% Duty Cycle}
n _{Ultralow Shutdown Current: IQ < 1μA}
n _{Output Voltages from 5V down to 0.6V}
n _{Power-On Reset Output}
n _{Externally Synchronizable Oscillator}
n _{Small Thermally Enhanced MSOP and 3mm × 3mm}
DFN Packages
APPLICATIONS
n _{PDAs/Palmtop PCs}
n _{Digital Cameras}
n _{Cellular Phones}
n _{Portable Media Players}
n _{PC Cards}
n _{Wireless and DSL Modems}
LTC3407
Dual Synchronous, 600mA,
1.5MHz Step-Down
DC/DC Regulator
DESCRIPTION
The LTC^®3407 is a dual, constant frequency, synchronous
step down DC/DC converter. Intended for low power ap-
plications, it operates from 2.5V to 5.5V input voltage
range and has a constant 1.5MHz switching frequency,
allowing the use of tiny, low cost capacitors and inductors
2mm or less in height. Each output voltage is adjustable
from 0.6V to 5V. Internal synchronous 0.35Ω, 1A power
switches provide high efficiency without the need for
external Schottky diodes.
A user selectable mode input is provided to allow the user
to trade-off ripple noise for low power efficiency. Burst
Mode^® operation provides high efficiency at light loads,
while pulse-skipping mode provides low ripple noise at
light loads.
To further maximize battery life, the P-channel MOSFETs
are turned on continuously in dropout (100% duty cycle),
and both channels draw a total quiescent current of only
40μA. In shutdown, the device draws <1μA.
L, LT, LTC, LTM, Burst Mode, Linear Technology and the Linear logo are registered trademarks
of Linear Technology Corporation. All other trademarks are the property of their respective
owners.
TYPICAL APPLICATION
V_IN = 2.5V
TO 5.5V
C1
10μF
V_OUT2 = 2.5V
AT 600mA
L2
2.2μH
C5, 22pF
RUN2 V_IN RUN1
MODE/SYNC
POR
LTC3407
SW2
SW1
R5
100k
RESET
L1
2.2μH
C4, 22pF
C3
10μF
R4
887k R3
280k
V_FB2
GND
V_FB1
R2
R1 887k
442k
V_OUT1 = 1.8V
AT 600mA
C2
10μF
C1, C2, C3: TAIYO YUDEN JMK316BJ106ML
L1, L2: MURATA LQH32CN2R2M33
Figure 1. 2.5V/1.8V at 600mA Step-Down Regulators
3407 TA01
LTC3407 Efficiency Curve
100
95
2.5V
90
1.8V
85
80
75
70
65
V_IN = 3.3V
Burst Mode OPERATION
NO LOAD ON OTHER CHANNEL
60
1
10
100
LOAD CURRENT (mA)
1000
3407 TA02
3407fa
1