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LTC3548EDD-2#PBF

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P16
LTC3548-2
1
35482fb
TYPICAL APPLICATION
FEATURES
APPLICATIONS
DESCRIPTION
Dual Synchronous,
Fixed /Adjustable Output, 2.25MHz
Step-Down DC/DC Regulator
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 profi le ≤1.2mm. For channel 1, the output voltage is
fi xed at 1.8V/800mA; for channel 2, the output voltage is
adjustable from 0.6V to V
IN
Internal synchronous 0.35Ω,
1.2A/0.7A power switches provide high effi ciency 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 effi ciency.
Burst Mode
®
operation provides high effi ciency at light
loads, while pulse-skipping 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 cur-
rent of only 40μA. In shutdown, the device draws <1μA.
Figure 1. 2.5V/1.8V at 400mA/800mA Step-Down Regulators
n
High Effi ciency: Up to 95%
n
1.8V/800mA Fixed Output and 400mA Adjustable
Output Voltage
n
Only 40μA Quiescent Current (Both Channels)
n
2.25MHz Constant-Frequency Operation
n
High Switch Current Limits: 1.2A and 0.7A
n
No Schottky Diodes Required
n
Low R
DS(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: I
Q
< 1μA
n
Power-On Reset Output
n
Externally Synchronizable Oscillator
n
Small, Thermally Enhanced 3mm × 3mm DFN Package
n
PDAs/Palmtop PCs
n
Digital Cameras
n
Cellular Phones
n
Portable Media Players
n
PC Cards
n
Wireless and DSL Modems
Effi ciency and Power Loss
vs Load Current
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..
LOAD CURRENT (mA)
1
80
EFFICIENCY (%)
POWER LOSS (mW)
90
100
10 100 1000
35482 F01b
70
75
85
95
65
60
1
100
1000
10
0.1
EFFICIENCY
POWER LOSS
V
IN
= 3.6V
V
OUT
= 1.8V
Burst Mode OPERATION
CHANNEL 1
NO LOAD ON CHANNEL 2
RUN2 V
IN
V
IN
2.8V TO 5.5V
V
OUT2
2.5V
400mA
V
OUT1
1.8V
800mA
RUN1
POR
SW1
V
OUT1
GND
V
FB2
SW2
MODE/SYNC
LTC3548-2
10μF
100k
RESET
68pF
2.2μH4.7μH
887k
280k
10μF
35482 F01
4.7μF
LTC3548-2
2
35482fb
ABSOLUTE MAXIMUM RATINGS
V
IN
Voltages .................................................–0.3V to 6V
V
OUT1
, V
FB2
Voltages ........................ –0.3V to V
IN
+ 0.3V
RUN1, RUN2 Voltages .................................–0.3V to V
IN
MODE/SYNC Voltage ........................ –0.3V to V
IN
+ 0.3V
SW1, SW2 Voltages ......................... –0.3V to V
IN
+ 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
(Note 1)
ORDER INFORMATION
LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE
LTC3548EDD-2#PBF LTC3548EDD-2#TRPBF LCDK
10-Lead (3mm × 3mm) Plastic DFN
–40°C to 85°C
Consult LTC Marketing for parts specifi ed with wider operating temperature ranges.
Consult LTC Marketing for information on non-standard lead based fi nish parts.
For more information on lead free part marking, go to:
http://www.linear.com/leadfree/
For more information on tape and reel specifi cations, go to:
http://www.linear.com/tapeandreel/
PIN CONFIGURATION
TOP VIEW
DD PACKAGE
10-LEAD (3mm × 3mm) PLASTIC DFN
10
11
9
6
7
8
4
5
3
2
1
V
FB2
RUN2
POR
SW2
MODE
/
SYNC
V
OUT1
RUN1
V
IN
SW1
GND
T
JMAX
= 125°C, θ
JA
= 40°C/W, θ
JC
= 3°C/W (4-LAYER BOARD)
EXPOSED PAD (PIN 11) IS GND, MUST BE SOLDERED TO PCB GND
ELECTRICAL CHARACTERISTICS
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
IN
Operating Voltage Range
l
2.5 5.5 V
I
FB2
Feedback Pin Input Current
l
30 nA
V
FB2
Feedback Voltage of Channel 2 (Note 3) 0°C ≤ T
A
≤ 85°C
–40°C ≤ T
A
≤ 85°C
l
0.588
0.585
0.6
0.6
0.612
0.612
V
V
V
OUT1
Output Voltage of Channel 1 (Note 3) 0°C ≤ T
A
≤ 85°C
–40°C ≤ T
A
≤ 85°C
l
1.764
1.755
1.8
1.8
1.836
1.836
V
V
ΔV
LINEREG
Reference Voltage Line Regulation V
IN
= 2.5V to 5.5V (Note 3) 0.3 0.5 %/V
ΔV
LOADREG
Output Voltage Load Regulation (Note 3) 0.5 %
I
S
Input DC Supply Current (Note 4)
Active Mode
Sleep Mode
Shutdown
V
OUT1
= 1.5V, V
FB2
= 0.5V
V
OUT1
= 1.9V, V
FB2
= 0.63V, MODE/SYNC = 3.6V
RUN = 0V, V
IN
= 5.5V, MODE/SYNC = 0V
700
40
0.1
950
60
1
μA
μA
μA
f
OSC
Oscillator Frequency V
OUT1
= 1.8V, V
FB2
= 0.6V
l
1.8 2.25 2.7 MHz
f
SYNC
Synchronization Frequency 2.25 MHz
I
LIM
Peak Switch Current Limit Channel 1
Peak Switch Current Limit Channel 2
V
IN
= 3V, Duty Cycle <35%
V
IN
= 3V, V
FB2
= 0.5V, Duty Cycle <35%
0.95
0.6
1.2
0.7
1.6
0.9
A
A
R
DS(ON)
Top Switch On-Resistance
Bottom Switch On-Resistance
(Note 6)
(Note 6)
0.35
0.30
0.45
0.45
Ω
Ω
I
SW(LKG)
Switch Leakage Current V
IN
= 5V, V
RUN
= 0V, V
FB2
= 0V, V
OUT1
= 0V 0.01 1 μA
The l denotes the specifi cations which apply over the full operating
temperature range, otherwise specifi cations are at T
A
= 25°C. V
IN
= 3.6V, unless otherwise specifi ed. (Note 2)
LTC3548-2
3
35482fb
ELECTRICAL CHARACTERISTICS
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: The LTC3548-2 is guaranteed to meet specifi ed performance from
0°C to 85°C. Specifi cations over the – 40°C to 85°C operating temperature
range are assured by design, characterization and correlation with
statistical process controls.
Note 3: The LTC3548-2 is tested in a proprietary test mode that connects
the output of the error amplifi er to an outside servo loop.
Note 4: Dynamic supply current is higher due to the internal gate charge
being delivered at the switching frequency.
Note 5: T
J
is calculated from the ambient T
A
and power dissipation P
D
according to the following formula: T
J
= T
A
+ (P
D
• θ
JA
).
Note 6: The DFN switch on-resistance is guaranteed by correlation to
wafer level measurements.
The l denotes the specifi cations which apply over the full operating
temperature range, otherwise specifi cations are at T
A
= 25°C. V
IN
= 3.6V, unless otherwise specifi ed. (Note 2)
TYPICAL PERFORMANCE CHARACTERISTICS
Burst Mode Operation
Load Step
Pulse-Skipping Mode
T
A
= 25°C unless otherwise specifi ed.
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
MODE
Mode Threshold Low
Mode Threshold High
0
V
IN
– 0.5
0 .5
V
IN
V
V
POR Power-On Reset Threshold V
OUT1
, V
FB2
Ramping Down, MODE/SYNC = 0V –8.5 %
Power-On Reset On-Resistance 100 200 Ω
Power-On Reset Delay 262,144 Cycles
V
RUN
RUN Threshold
l
0.3 1 1.5 V
I
RUN
RUN Leakage Current
l
0.01 1 μA
35482 G01
V
IN
= 3.6V
V
OUT
= 1.8V
I
LOAD
= 60mA
CHANNEL 1; CIRCUIT OF FIGURE 3
SW
5V/DIV
V
OUT
20mV/DIV
I
L
200mA/
DIV
2μs/DIV
35482 G02
V
IN
= 3.6V
V
OUT
= 1.8V
I
LOAD
= 30mA
CHANNEL 1; CIRCUIT OF FIGURE 3
SW
5V/DIV
V
OUT
10mV/DIV
I
L
200mA/DIV
1μs/DIV
35482 G03
V
IN
= 3.6V
V
OUT
= 1.8V
I
LOAD
= 80mA TO 800mA
CHANNEL 1; CIRCUIT OF FIGURE 3
V
OUT
200mV/DIV
I
L
500mA/DIV
I
LOAD
500mA/DIV
20μs/DIV
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P16

LTC3548EDD-2#PBF

Mfr. #:
Buy LTC3548EDD-2#PBF
Manufacturer:
Analog Devices / Linear Technology
Description:
Switching Voltage Regulators DC/DC Regulator Fixed/Adjustable 1.8V/0.8A &0.6V to 5V
Lifecycle:
New from this manufacturer.
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