DC/DC Regulator. LTC3548-2 Datasheet

LTC3548-2 Regulator. Datasheet pdf. Equivalent

Part LTC3548-2
Description Step-Down DC/DC Regulator
Feature www.DataSheet4U.com LTC3548-2 Dual Synchronous, Fixed/Adjustable Output, 2.25MHz Step-Down DC/DC Re.
Manufacture Linear Technology
Datasheet
Download LTC3548-2 Datasheet




LTC3548-2
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LTC3548-2
Dual Synchronous,
Fixed/Adjustable Output, 2.25MHz
Step-Down DC/DC Regulator
FEATURES
High Efficiency: Up to 95%
1.8V/800mA Fixed Output and 400mA Adjustable
Output Voltage
Only 40µA Quiescent Current (Both Channels)
2.25MHz Constant Frequency Operation
High Switch Current Limits: 1.2A and 0.7A
No Schottky Diodes Required
Low RDS(ON) Internal Switches: 0.35
Current Mode Operation for Excellent Line
and Load Transient Response
Short-Circuit Protected
Low Dropout Operation: 100% Duty Cycle
Ultralow Shutdown Current: IQ < 1µA
Power-On Reset Output
Externally Synchronizable Oscillator
Small
Thermally
Enhanced
U
3mm
×
3mm
DFN
Package
APPLICATIO S
PDAs/Palmtop PCs
Digital Cameras
Cellular Phones
Portable Media Players
PC Cards
Wireless and DSL Modems
DESCRIPTIO
The LTC®3548-2 is a dual, constant frequency, synchro-
nous step down DC/DC converter. Intended for low power
applications, it operates from 2.5V to 5.5V input voltage
range and has a constant 2.25MHz switching frequency,
allowing the use of tiny, low cost capacitors and inductors
with a profile 1.2mm. For channel 1, the output voltage
is fixed at 1.8V/800mA; for channel 2, the output voltage
is adjustable from 0.6V to VIN. Internal synchronous
0.35, 1.2A/0.7A power switches provide high efficiency
without the need for external Schottky diodes.
A user selectable mode input is provided to allow the user
to trade-off noise ripple for low power efficiency. Burst
Mode® operation provides high efficiency at light loads,
while Pulse Skip Mode provides low noise ripple at light
loads.
To further maximize battery run time, the P-channel
MOSFETs are turned on continuously in dropout (100%
duty cycle), and both channels draw a total quiescent
current of only 40µA. In shutdown, the device draws <1µA.
, LTC and LT are registered trademarks of Linear Technology Corporation. All other
trademarks are the property of their respective owners. Burst Mode is a registered
trademark of Linear Technology Corporation. Protected by U.S. Patents including 5481178,
6580258, 6304066, 6127815, 6498466, 6611131.
TYPICAL APPLICATIO
VIN
2.8V TO 5.5V
10µF
VOUT2
2.5V
400mA
4.7µH
68pF
RUN2 VIN RUN1
MODE/SYNC
POR
LTC3548-2
SW2 SW1
100k
RESET
2.2µH
VOUT1
1.8V
800mA
887k
4.7µF
280k
VFB2
VOUT1
GND
10µF
35482 F01
Figure 1. 2.5V/1.8V at 400mA/800mA Step-Down Regulators
100
95
90
85
80
75
70
65
60
1
Efficiency and Power Loss
vs Load Current
1000
EFFICIENCY
POWER LOSS
100
10
VIN = 3.6V
VOUT = 1.8V
Burst Mode OPERATION
1
CHANNEL 1
NO LOAD ON CHANNEL 2
0.1
10 100 1000
LOAD CURRENT (mA)
35482 F01b
35482f
1



LTC3548-2
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LTC3548-2
ABSOLUTE AXI U RATI GS
(Note 1)
VIN Voltages.................................................– 0.3V to 6V
VOUT1, VFB2, RUN1, RUN2
Voltages .......................................... – 0.3V to VIN + 0.3V
MODE/SYNC Voltage ...................... – 0.3V to VIN + 0.3V
SW1, SW2 Voltage ......................... – 0.3V to VIN + 0.3V
POR Voltage ................................................– 0.3V to 6V
Ambient Operating Temperature Range
(Note 2) .................................................. – 40°C to 85°C
Junction Temperature (Note 5) ............................. 125°C
Storage Temperature Range ................. – 65°C to 125°C
UW U
PACKAGE/ORDER I FOR ATIO
TOP VIEW
VOUT1
RUN1
VIN
SW1
GND
1
2
3
4
5
10 VFB2
9 RUN2
11 8 POR
7 SW2
6 MODE/
SYNC
DD PACKAGE
10-LEAD (3mm × 3mm) PLASTIC DFN
TJMAX = 125°C, θJA = 40°C/W, θJC = 3°C/W (4-LAYER BOARD)
EXPOSED PAD (PIN 11) IS GND, MUST BE SOLDERED TO PCB GND
ORDER PART NUMBER DD PART MARKING
LTC3548EDD-2
LCDK
Order Options Tape and Reel: Add #TR
Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF
Lead Free Part Marking: http://www.linear.com/leadfree/
Consult LTC Marketing for parts specified with wider operating temperature ranges.
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 specified. (Note 2)
SYMBOL
PARAMETER
CONDITIONS
MIN TYP MAX UNITS
VIN Operating Voltage Range
2.5
5.5
IFB2 Feedback Pin Input Current
30
VFB2 Feedback Voltage of Channel 2 (Note 3) 0°C TA 85°C
–40°C TA 85°C
0.588 0.6 0.612
0.585 0.6 0.612
VOUT1
Output Voltage of Channel 1 (Note 3)
0°C TA 85°C
–40°C TA 85°C
1.764 1.8 1.836
1.755 1.8 1.836
VLINE REG Reference Voltage Line Regulation
VIN = 2.5V to 5.5V (Note 3)
0.3 0.5
VLOAD REG Output Voltage Load Regulation
(Note 3)
0.5
IS Input DC Supply Current (Note 4)
Active Mode
VOUT1 = 1.5V, VFB2 = 0.5V
Sleep Mode
VOUT1 = 1.9V, VFB2 = 0.63V, MODE/SYNC = 3.6V
Shutdown
RUN = 0V, VIN = 5.5V, MODE/SYNC = 0V
700 950
40 60
0.1 1
fOSC Oscillator Frequency
VOUT1 = 1.8V, VFB2 = 0.6V
1.8 2.25 2.7
fSYNC
Synchronization Frequency
2.25
ILIM
Peak Switch Current Limit Channel 1
VIN = 3V, Duty Cycle <35%
Peak Switch Current Limit Channel 2
VIN = 3V, VFB2 = 0.5V, Duty Cycle <35%
0.95 1.2
0.6 0.7
1.6
0.9
RDS(ON)
Top Switch On-Resistance
Bottom Switch On-Resistance
(Note 6)
(Note 6)
0.35 0.45
0.30 0.45
V
nA
V
V
V
V
%/V
%
µA
µA
µA
MHz
MHz
A
A
ISW(LKG)
Switch Leakage Current
VIN = 5V, VRUN = 0V, VFB2 = 0V, VOUT1 = 0V
0.01 1
µA
35482f
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