LTC3541EDD-2 查看數據表（PDF） - Linear Technology
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LTC3541EDD-2 Datasheet PDF : 22 Pages
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LTC3541-2
High Efficiency
Buck + VLDO Regulator
FEATURES
nn High Efficiency, 500mA Buck Plus 300mA VLDO
Regulator
nn Auto Start-Up Powers Buck Output Prior to VLDO/
Linear Regulator Output
nn Independent 500mA High Efficiency Buck
(VIN: 2.7V to 5.5V)
nn 300mA VLDO Regulator with 30mA Standalone Mode
nn No External Schottky Diodes Required
nn Fixed Buck Output Voltage: 1.875V
nn VLDO Input Voltage Range (LVIN: 1.6V to 5.5V)
nn Fixed VLDO Output Voltage: 1.5V
nn Selectable Fixed Frequency, Pulse-Skip Operation
nn or Burst Mode® Operation
nn Short-Circuit Protected
nn Current Mode Operation for Excellent Line and Load
Transient Response
nn Shutdown Current: <3µA
nn Constant Frequency Operation: 2.25MHz
nn Low Dropout Buck Operation: 100% Duty Cycle
nn Small, Thermally Enhanced, 10-Lead (3mm × 3mm)
DFN Package
APPLICATIONS
nn Digital Cameras
nn Cellular Phones
nn PC Cards
nn Wireless and DSL Modems
nn Other Portable Power Systems
DESCRIPTION
The LTC®3541-2 combines a synchronous buck DC/
DC converter with a very low dropout linear regulator
(VLDOTMregulator) and internal feedback resistor networks
to provide two output voltages from a single input volt-
age with minimal external components. When configured
for dual output operation, the LTC3541-2’s auto start-up
feature will bring the 1.875V buck output into regulation
in a controlled manner, prior to enabling the 1.5V VLDO
output without the need for external pin control. The 1.5V
VLDO/linear regulator output prior to 1.875V buck output
sequencing may also be obtained via external pin control.
The input voltage range is ideally suited for Li-Ion battery
applications powering sub-3.3V logic from 5V or 3.3V rails.
The synchronous buck converter provides a high efficiency
output, typically 90%. It can provide up to 500mA of output
current while switching at 2.25MHz, allowing the use of
small surface mount inductors and capacitors. A mode-
select pin allows Burst Mode operation to be enabled for
higher efficiency at light load currents, or disabled for lower
noise, constant frequency operation.
The VLDO regulator provides a low noise, low voltage
output capable of providing up to 300mA of output current
using only a 2.2µF ceramic capacitor. The input supply
voltage of the VLDO regulator (LVIN) may come from the
buck regulator output or a separate supply.
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and VLDO is a
trademark of Linear Technology Corporation. All other trademarks are the property of their respective
owners. Protected by U.S. Patents, including 5481178, 6611131, 6304066, 6498466, 6580258.
TYPICAL APPLICATION
VIN
2.9V TO 5.5V
VOUT1
1.875V
200mA
10µF
2.2µH
10µF
VIN
ENBUCK ENVLDO
SW
MODE
LTC3541-2
VOUT
LVIN
LVOUT
PGND
GND
VOUT2
1.5V
300mA
2.2µF
35412 TA01a
Buck (Burst) Efficiency vs Load Current
100
VIN = 3V
90
80
EFFICIENCY
70
60
POWER LOSS
50
40
30
20
10
0
1
10
100
LOAD CURRENT (mA)
1
0.1
0.01
0.001
0.0001
1000
35412 TA01b
For more information www.linear.com/LTC3541-2
35412fc
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