LTC3417_15 Datasheet, PDF (1/20 Pages) Linear Technology – Dual Synchronous 1.4A/800mA 4MHz Step-Down DC/DC Regulator

LTC3417
FEATURES
Dual Synchronous
1.4A/800mA 4MHz
Step-Down DC/DC Regulator
DESCRIPTION
n _{High Efficiency: Up to 95%}
n _{1.4A/800mA Guaranteed Minimum Output Current}
n _{No Schottky Diodes Required}
n _{Programmable Frequency Operation: 1.5MHz or}
Adjustable From 0.6MHz to 4MHz
n _{Low RDS(ON) Internal Switches}
n _{Short-Circuit Protected}
n _{VIN: 2.25V to 5.5V}
n _{Current Mode Operation for Excellent Line and}
Load Transient Response
n _{125μA Quiescent Current in Sleep Mode}
n _{Ultralow Shutdown Current: IQ < 1μA}
n _{Low Dropout Operation: 100% Duty Cycle}
n _{Power Good Output}
n _{Phase Pin Selects 2nd Channel Phase Relationship}
with Respect to 1st Channel
n _{Internal Soft-Start with Individual Run Pin Control}
n _{Available in Small Thermally Enhanced}
(5mm × 3mm) DFN and 20-Lead TSSOP Packages
APPLICATIONS
n _{PDAs/Palmtop PCs}
n _{Digital Cameras}
n _{Cellular Phones}
n _{PC Cards}
n _{Wireless and DSL Modems}
The LTC^®3417 is a dual constant frequency, synchronous
step-down DC/DC converter. Intended for medium power
applications, it operates from a 2.25V to 5.5V input volt-
age range and has a constant programmable switching
frequency, allowing the use of tiny, low cost capacitors
and inductors 2mm or less in height. Each output voltage
is adjustable from 0.8V to 5V. Internal synchronous low
R_DS(ON) power switches provide high efficiency without
the need for external Schottky diodes.
A user selectable mode input allows the user to trade
off ripple voltage for light load efficiency. Burst Mode^®
operation provides high efficiency at light loads, while
Pulse Skip mode provides low ripple noise at light loads.
A phase mode pin allows the second channel to operate
in-phase or 180° out-of-phase with respect to channel 1.
Out-of-phase operation produces lower RMS current on
V_IN and thus lower RMS derating on the input capacitor.
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
125μA. In shutdown, the device draws <1μA.
L, 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, 6580258, 6304066, 6127815, 6498466, 6611131, 6144194.
TYPICAL APPLICATION
V_IN
2.5V TO 5.5V
V_OUT1
1.8V
1.4A
22μF
10μF
1.5μH
22pF
V_IN
511k
412k
5.9k
2200pF
V_IN
FREQ
SW1
SW2
RUN1
RUN2
LTC3417
V_FB1
V_FB2
I_TH1
I_TH2
GND
2.2μH
22pF
V_IN
866k
412k
2.87k
6800pF
3417 TA01
V_OUT2
2.5V
800mA
10μF
OUT2 Efficiency
(Burst Mode Operation)
100 _{REFER TO FIGURE 4}
10
95
1
EFFICIENCY
90
0.1
85
0.01
80
POWER LOSS
75
70
0.001
0.001
V_IN = 3.6V
V_OUT = 2.5V
FREQ = 1MHz _0.0001
0.01
0.1
1
LOAD CURRENT (A)
3417 TA01a
3417fd
1