Buck Regulator. LTC3672B-1 Datasheet

LTC3672B-1 Regulator. Datasheet pdf. Equivalent

Part LTC3672B-1
Description Monolithic Fixed-Output 400mA Buck Regulator
Feature www.DataSheet4U.com LTC3672B-1 Monolithic Fixed-Output 400mA Buck Regulator with Dual 150mA LDOs in.
Manufacture Linear Technology
Datasheet
Download LTC3672B-1 Datasheet



LTC3672B-1
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LTC3672B-1
Monolithic Fixed-Output
400mA Buck Regulator with Dual
150mA LDOs in 2mm × 2mm DFN
FEATURES
Triple Output Supply From a Single 2.9V to 5.5V Input
Buck DC/DC: Fixed 1.8V Output, Up to 400mA
LDO1: Fixed 1.2V Output, Up to 150mA
LDO2: Fixed 2.8V Output, Up to 150mA
±2.5% Reference Accuracy
Constant Frequency 2.25MHz Operation
Minimum External Component Count
Current Mode Operation for Excellent Line and Load
Transient Response
Internal Soft-Start for Each Output
Single Enable Pin Turns On/Shuts Down All Three
Outputs
Tiny 2mm × 2mm × 0.75mm DFN Package
APPLICATIONS
DMB Cellphones
Handheld Products (PDA, PMP, GPS)
Multivoltage Power for Digital Logic, I/O, FPGAs,
CPLDs, ASICs, CPUs, and RF Chipsets
DESCRIPTION
The LTC®3672B-1 is a triple power supply composed of a
400mA synchronous buck regulator and two 150mA low-
dropout linear regulators (LDOs), where one of the LDOs
can be powered from the buck output to improve efficiency.
Constant-frequency 2.25MHz operation is maintained
down to very light loads. The input supply range of 2.9V
to 5.5V is especially well-suited for single-cell Lithium-Ion
and Lithium-Polymer applications, and for powering low
voltage ASICs from 3.3V or 5V rails.
The LTC3672B-1 regulates 1.8V at the buck output, 1.2V
at the LDO1 output, and 2.8V at the LDO2 output. Exter-
nal component count is minimal—all that is needed is a
single inductor, an input capacitor, and output capacitors
for each of the three outputs. Control loop compensation
is internal to the LTC3672B-1.
The LTC3672B-1 is available in a 2mm × 2mm × 0.75mm
8-Lead DFN package.
L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other
trademarks are the property of their respective owners.
TYPICAL APPLICATION
VIN
2.9V TO 5.5V
2.2MF
ENABLE
INPUT
4.7MH
VIN SW
GND BUCKOUT
ENALL
VIN1
LDO1
LTC3672B-1
LDO2
3672b1 TA01
10MF
1MF
1MF
VOUT1
1.8V
400mA
(250mA IF LDO1
FULLY-LOADED)
VOUT2
1.2V
150mA
VOUT3
2.8V
UP TO 150mA
(SUBJECT TO DROPOUT
LIMITATIONS)
Buck DC/DC Efficiency vs Load
100
95 VIN = 2.9V
90
85
80 VIN = 5.5V
VIN = 3.6V
75
70
65
60
0
50 100 150 200 250 300 350 400
ILOAD (mA)
3672b1 TA01b
3672B1f
1



LTC3672B-1
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LTC3672B-1
ABSOLUTE MAXIMUM RATINGS
(Notes 1, 2, 3)
VIN ............................................................... –0.3V to 6V
VIN1, BUCKOUT, ENALL, SW,
LDO2 ...........–0.3V to the lesser of (VIN + 0.3V) or 6V
LDO1 ............. –0.3V to the lesser of (VIN1 + 0.3V) or 6V
Junction Temperature ........................................... 125°C
Operating Temperature Range...................... –40 to 85°C
Storage Temperature Range....................... –65 to 125°C
PIN CONFIGURATION
TOP VIEW
SW 1
8 VIN
GND 2
7 LDO2
9
ENALL 3
6 LDO1
BUCKOUT 4
5 VIN1
DC PACKAGE
8-LEAD (2mm s 2mm) PLASTIC DFN
TJMAX = 125°C, θJA = 102°C/W, θJC = 20°C/W
EXPOSED PAD (PIN 9) IS GND, MUST BE SOLDERED TO PCB
ORDER INFORMATION
LEAD FREE FINISH
TAPE AND REEL
PART MARKING*
PACKAGE DESCRIPTION
LTC3672BEDC-1#PBF
LTC3672BEDC-1#TRPBF LCWH
8-Lead (2mm × 2mm) Plastic DFN
Consult LTC Marketing for parts specified with wider operating temperature ranges.
Consult LTC Marketing for information on non-standard lead based finish parts.
*For more information on lead free part marking, go to: http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/
TEMPERATURE RANGE
–40°C to 85°C
ELECTRICAL CHARACTERISTICS The denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VIN = 3.6V, unless otherwise noted.
SYMBOL
PARAMETER
CONDITIONS
MIN TYP MAX UNITS
VIN
VUVLO
Input Voltage Range
VIN Undervoltage Lockout Threshold
Undervoltage Lockout Hysteresis
VIN Rising
2.9
5.5
1.7 2
12 100
V
V
mV
IQ,VIN
VIN Quiescent Current
All Outputs Enabled, No Load
Shutdown
IQ,VIN1
VIN1 Quiescent Current
All Outputs Enabled, No Load
Shutdown
VIL ENALL Pin Logic Low Voltage
VIH ENALL Pin Logic High Voltage
RENALL
ENALL Pin Pulldown Resistance
Synchronous Buck Regulator
(Note 4)
VBUCKOUT = 1.9V
VENALL = 0V
VIN1 = 1.8V
VENALL = 0V
260 400
1
2.3 5
1
0.4
1.2
5.5
μA
μA
μA
μA
V
V
MΩ
fOSC
VBUCKOUT
IMAXP
IOUT,BUCK
RP,BUCK
RN,BUCK
Oscillator Frequency
Regulated Output Voltage
PMOS Switch Maximum Peak Current (Note 5)
Available Output Current
PMOS Switch On-Resistance
NMOS Switch On-Resistance
1.8 2.25 2.7
1.755 1.8 1.845
550 800 1100
400
0.6
0.7
MHz
V
mA
mA
Ω
Ω
3672B1f
2







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