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Linear Technology Electronic Components Datasheet

LTC3548EMSE Datasheet

Step-Down DC/DC Regulator

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LTC3548
Dual Synchronous,
400mA/800mA, 2.25MHz
Step-Down DC/DC Regulator
FEATURES
n High Efficiency: Up to 95%
n Very Low Quiescent Current: Only 40μA
n Low Output Ripple Burst Mode® Operation
n 2.25MHz Constant-Frequency Operation
n High Switch Current: 0.7A and 1.2A
n No Schottky Diodes Required
n Low RDS(ON) Internal Switches: 0.35Ω
n Current Mode Operation for Excellent Line
and Load Transient Response
n Short-Circuit Protected
n Low Dropout Operation: 100% Duty Cycle
n Ultralow Shutdown Current: IQ < 1μA
n Output Voltages from 5V down to 0.6V
n Power-On Reset Output
n Externally Synchronizable Oscillator
n Small Thermally Enhanced MSOP and 3mm × 3mm
DFN Packages
APPLICATIONS
PDAs/Palmtop PCs
Digital Cameras
Cellular Phones
Portable Media Players
PC Cards
Wireless and DSL Modems
DESCRIPTION
The LTC®3548 is a dual, constant-frequency, synchronous
step down DC/DC converter. Intended for low power ap-
plications, 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 ≤1mm. Each output voltage is adjustable
from 0.6V to 5V. Internal synchronous 0.35Ω, 0.7A/1.2A
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-skipping mode provides low noise ripple at
light loads.
To further maximize battery runtime, the P-channel
MOSFETs are turned on continuously in dropout (100%
duty cycle), and both channels draw a total quiescent cur-
rent of only 40μA. In shutdown, the device draws <1μA.
L, LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks
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
VIN = 2.8V
TO 5.5V
VOUT2 = 2.5V
AT 400mA
10μF
4.7μH
68pF
RUN2 VIN RUN1
MODE/SYNC
POR
LTC3548
SW2
SW1
100k
RESET
2.2μH
33pF
VOUT1 = 1.8V
AT 800mA
VFB2
887k
VFB1
4.7μF
280k
GND
604k
301k
10μF
3548 TA01
Figure 1. 2.5V/1.8V at 400mA/800mA Step-Down Regulators
LTC3548 Efficiency Curve
100
1000
95
90
EFFICIENCY
100
85
80
10
POWER LOSS
75
70
65
60
1
1
VIN = 3.3V, VOUT = 1.8V
Burst Mode OPERATION
CHANNEL 1, NO LOAD ON CHANNEL 2 0.1
10
100
1000
LOAD CURRENT (mA)
3548 TA02
3548fc
1


Linear Technology Electronic Components Datasheet

LTC3548EMSE Datasheet

Step-Down DC/DC Regulator

No Preview Available !

LTC3548
ABSOLUTE MAXIMUM RATINGS
(Note 1)
VIN Voltages .................................................– 0.3V to 6V
VFB1, VFB2 Voltages ...........................– 0.3V to VIN +0.3V
RUN1, RUN2 Voltages ................................ – 0.3V to VIN
MODE/SYNC Voltage .......................– 0.3V to VIN + 0.3V
SW1, SW2 Voltage...........................– 0.3V to VIN + 0.3V
POR Voltage.................................................– 0.3V to 6V
Operating Temperature Range (Note 2)....–40°C to 85°C
Junction Temperature (Note 5) ............................. 125°C
Storage Temperature Range...................– 65°C to 125°C
Lead Temperature (Soldering, 10 sec)
MSE Only.......................................................... 300°C
PIN CONFIGURATION
TOP VIEW
VFB1 1
RUN1 2
VIN 3
SW1 4
GND 5
10 VFB2
9 RUN2
11
8 POR
7 SW2
6 MODE/
SYNC
DD PACKAGE
10-LEAD (3mm s 3mm) PLASTIC DFN
TJMAX = 125°C, θJA = 45°C/W, θJC = 3°C/W
EXPOSED PAD (PIN 11) IS PGND, MUST BE CONNECTED TO GND
(SOLDERED TO A 4-LAYER BOARD)
TOP VIEW
VFB1 1
RUN1 2
10 VFB2
9 RUN2
VIN 3
11
8 POR
SW1 4
7 SW2
GND 5
6 MODE/
SYNC
MSE PACKAGE
10-LEAD PLASTIC MSOP
TJMAX = 125°C, θJA = 45°C/W, θJC = 10°C/W
EXPOSED PAD (PIN 11) IS PGND, MUST BE CONNECTED TO GND
(SOLDERED TO A 4-LAYER BOARD)
ORDER INFORMATION
LEAD FREE FINISH
TAPE AND REEL
PART MARKING*
PACKAGE DESCRIPTION
TEMPERATURE RANGE
LTC3548EDD#PBF
LTC3548EDD#TRPBF
LBNJ
10-Lead (3mm × 3mm) Plastic DFN –40°C to 85°C
LTC3548IDD#PBF
LTC3548EMSE#PBF
LTC3548IDD#TRPBF
LTC3548EMSE#TRPBF
LBNJ
LTBNH
10-Lead (3mm × 3mm) Plastic DFN
10-Lead Plastic MSOP
–40°C to 85°C
–40°C to 85°C
LTC3548IMSE#PBF
LTC3548IMSE#TRPBF LTBNH
10-Lead Plastic MSOP
–40°C to 85°C
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
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/
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
VIN
Operating Voltage Range
l 2.5
5.5
IFB
Feedback Pin Input Current
l
30
VFB
Feedback Voltage (Note 3)
0°C ≤ TA ≤ 85°C
–40°C ≤ TA ≤ 85°C
0.588 0.6 0.612
l 0.585 0.6 0.612
ΔVLINEREG
Reference Voltage Line Regulation
VIN = 2.5V to 5.5V (Note 3)
0.3
0.5
UNITS
V
nA
V
V
%V
3548fc
2


Part Number LTC3548EMSE
Description Step-Down DC/DC Regulator
Maker Linear
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