LTC3419 Datasheet, PDF (1/16 Pages) Linear Technology – Dual Monolithic 600mA Synchronous Step-Down Regulator

FEATURES
■ _{High Efficiency Dual Step-Down Outputs: Up to 96%}
■ _{600mA Current per Channel at VIN = 3V}
■ _{Only 35μA Quiescent Current During Operation}
(Both Channels)
■ _{2.25MHz Constant-Frequency Operation}
■ _{2.5V to 5.5V Input Voltage Range}
■ _{Low Dropout Operation: 100% Duty Cycle}
■ _{No Schottky Diodes Required}
■ _{Internally Compensated for All Ceramic Capacitors}
■ _{Independent Internal Soft-Start for Each Channel}
■ _{Available in Fixed Output Versions}
■ _{Current Mode Operation for Excellent Line and Load}
Transient Response
■ _{0.6V Reference Allows Low Output Voltages}
■ _{User-Selectable Burst Mode}^® _Operation
■ _{Short-Circuit Protected}
■ _{Ultralow Shutdown Current: IQ < 1μA}
■ _{Available in Small MSOP or 3mm × 3mm}
DFN-8 Packages
APPLICATIONS
■ _{Cellular Telephones}
■ _{Digital Still Cameras}
■ _{Wireless and DSL Modems}
■ _{Portable Media Players}
■ _{PDAs/Palmtop PCs}
LTC3419
Dual Monolithic 600mA
Synchronous Step-Down
Regulator
DESCRIPTION
The LTC^®3419 is a dual, 2.25MHz, constant-frequency,
synchronous step-down DC/DC converter in a tiny
3mm × 3mm DFN package. 100% duty cycle provides
low dropout operation, extending battery life in portable
systems. Low output voltages are supported with the 0.6V
feedback reference voltage. Each regulator can supply
600mA output current.
The input voltage range is 2.5V to 5.5V, making it ideal
for Li-Ion and USB powered applications. Supply cur-
rent during operation is only 35μA and drops to <1μA in
shutdown. A user-selectable mode input allows the user
to trade off between high efficiency Burst Mode operation
and pulse-skipping mode.
An internally set 2.25MHz switching frequency allows the
use of tiny surface mount inductors and capacitors. Inter-
nal soft-start reduces inrush current during start-up. Both
outputs are internally compensated to work with ceramic
output capacitors. The LTC3419 is available in a low profile
(0.75mm) 3mm × 3mm DFN package. The LTC3419 is also
available in a fixed output voltage configuration selected
via internal resistor dividers (see Table 2).
, LT, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
Burst Mode is a registered trademark of Linear Technology Corporation. All other
trademarks are the property of their respective owners. Protected by U.S. Patents,
including 5481178, 6127815, 6304066, 6498466, 6580258, 6611131.
TYPICAL APPLICATION
Dual Monolithic Buck Regulator in 8-Lead 3 × 3 DFN
V_IN
2.5V TO 5.5V
10μF
V_OUT2
1.8V AT
600mA
3.3μH
22pF
RUN2 V_IN RUN1
MODE
LTC3419
SW2
SW1
3.3μH
22pF
V_OUT1
2.5V AT
600mA
10μF ^118k
V_FB2
V_FB1
GND
59k
59k ^187k
10μF
3419 TA01
Efficiency and Power Loss vs
Output Current
100 _{VIN = 3.6V}
10
90
80
1
70
60
0.1
50
40
0.01
30
20
10
0
0.1
V_OUT = 1.2V
V_OUT = 1.8V
V_OUT = 2.5V
0.001
0.0001
1
10
100
1000
OUTPUT CURRENT (mA)
3419 TA01b
3419f
1