LTC3670
Monolithic 400mA Buck
Regulator with Dual 150mA
LDOs in 3mm × 2mm DFN
DESCRIPTION
FEATURES
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Triple Output Supply from a Single 2.5V to 5.5V Input
400mA Buck DC/DC Plus Dual 150mA LDOs in One IC
Outputs Regulate Down to 0.8V
±2.5% Reference Accuracy
Constant-Frequency 2.25MHz Operation
Burst Mode® Operation for High Efficiency at Light
Loads; IQ = 70μA, All Outputs Enabled
Independent Enable Pin for Each Output
Current Mode Operation for Excellent Line and Load
Transient Response
Internal Soft-Start for Each Output
Tiny 12-Lead 3mm × 2mm × 0.75mm DFN Package
APPLICATIONS
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Handheld Products
Portable Instruments
Single-Cell Li-Ion/Li-Polymer Powered Devices
DMB/DVB-H Multimedia Cell Phones
Multivoltage Power for Digital Logic, I/O, FPGAs,
CPLDs, ASICs, SoCs, CPUs and RF Chipsets
The LTC®3670 is a triple power supply composed of a
400mA synchronous buck regulator and two 150mA low
dropout linear regulators (LDOs). The input supply range
of 2.5V to 5.5V is especially well-suited for single-cell
Lithium-Ion and Lithium-Ion/Polymer applications, and
for powering low voltage ASICs and SoCs from 3V, 3.3V
or 5V rails. Regulated output voltages are programmed
via external resistors. Each output has its own enable pin
for maximum flexibility.
The 400mA buck regulator features constant-frequency
2.25MHz operation, allowing small surface mount inductors and capacitors to be used. Burst Mode operation
maintains high efficiency in light-load and no-load conditions. Internal control-loop compensation simplifies
application design.
The LTC3670 is available in a 0.75mm profile, 3mm ×
2mm 12-lead DFN package.
L, LT, LTC, LTM and Burst Mode are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners. Patents pending.
TYPICAL APPLICATION
Triple Power Supply with Independent Enables
Demoboard
VIN
3.3V TO 5.5V
2.2μF
VIN
4.7μH
GND
SW
232k
10pF
4.7μF
VOUT1
1.2V
400mA
BUCKFB
464k
9.3mm
LTC3670
DIGITAL
CONTROL
ENBUCK
ENLDO1
ENLDO2
PGOOD
LDO1
806k
1μF
VOUT2
2.8V
150mA
LDO1_FB
9.4mm
ACTIVE AREA
324k
LDO2
1.02M
1μF
VOUT3
3.3V
150mA
3670 TA01b
LDO2_FB
324k
3670 TA01a
3670f
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