Switching frequency is internally set at 2.25MHz, allowing
the use of small surface mount inductors and capacitors.
For noise sensitive applications the LTC3560 can be ex-
ternally synchronized from 1MHz to 3MHz. Burst Mode
operation is inhibited during synchronization or when the
SYNC/MODE pin is pulled high, preventing low frequency
ripple from interfering with audio circuitry.
The internal synchronous switch increases efficiency
and eliminates the need for an external Schottky diode.
Low output voltages are easily supported with the 0.6V
feedback reference voltage. The LTC3560 is available in a
low profile (1mm) ThinSOT package.
L,
LT, LTC, LTM and Burst Mode are registered trademarks of Linear Technology Corporation.
ThinSOT is a trademark of Linear Technology Corporation. All other trademarks are the property
of their respective owners. Protected by U.S. Patents including 6580258, 5481178, 5994885,
6304066, 6498466, 6611131.
High Efficiency: Up to 95%
Low Output Ripple (<20mV
P-P
): Burst Mode
®
Operation: I
Q
= 16μA
2.5V to 5.5V Input Voltage Range
2.25MHz Constant Frequency Operation
Synchronizable to External Clock
No Schottky Diode Required
Stable with Ceramic Capacitors
Low Dropout Operation: 100% Duty Cycle
0.6V Reference Allows Low Output Voltages
Shutdown Mode Draws < 1μA Supply Current
±2% Output Voltage Accuracy
Current Mode Operation for Excellent Line and
Load Transient Response
Overtemperature Protected
Low Profile (1mm) ThinSOT™ Package
APPLICATIONS
n
n
n
n
n
Cellular Telephones
Wireless and DSL Modems
Digital Still Cameras
Media Players
Portable Instruments
TYPICAL APPLICATION
100
90
80
EFFICIENCY (%)
70
60
50
40
30
20
806k
3405A F01a
1
0.1
POWER LOSS (W)
V
IN
2.7V
TO 5.5V
2.2μH
C
IN
10μF
CER
V
IN
LTC3560
RUN
SYNC/MODE V
FB
GND
255k
SW
10pF
C
OUT
10μF
CER
V
OUT
2.5V
0.01
0.001
V
IN
= 3.6V
V
IN
= 4.2V
V
IN
= 5.5V
1
10
100
LOAD CURRENT (mA)
0.0001
1000
3560 F01b
10
0
0.1
Figure 1a. High Efficiency Step-Down Converter
Figure 1b. Efficiency vs Load Current
3560fb
1
LTC3560
ABSOLUTE MAXIMUM RATINGS
(Note 1)
PIN CONFIGURATION
TOP VIEW
RUN 1
GND 2
SW 3
6 SYNC/MODE
5 V
FB
4 V
IN
Input Supply Voltage ................................... – 0.3V to 6V
SYNC/MODE, RUN, V
FB
Voltages ............... – 0.3V to V
IN
SW Voltage (DC) .......................... – 0.3V to (V
IN
+ 0.3V)
P-Channel Switch Source Current (DC) (Note 6)..... 1.2A
N-Channel Switch Sink Current (DC) (Note 6) ........ 1.2A
Peak SW Sink and Source Current (Note 6) ........... 2.1A
Operating Temperature Range (Note 2)
LTC3560E.............................................–40°C to 85°C
LTC3560I............................................–40°C to 125°C
Junction Temperature (Notes 3, 7) ...................... 125°C
Storage Temperature Range.................. – 65°C to 150°C
Lead Temperature (Soldering, 10 sec) ................. 300°C
S6 PACKAGE
6-LEAD PLASTIC TSOT-23
T
JMAX
= 125°C,
θ
JA
= 250°C/W
ORDER INFORMATION
LEAD FREE FINISH
LTC3560ES6#PBF
LTC3560IS6#PBF
TAPE AND REEL
LTC3560ES6#TRPBF
LTC3560IS6#TRPBF
PART MARKING*
LTCFY
LTCFY
PACKAGE DESCRIPTION
6-Lead Plastic TSOT-23
6-Lead Plastic TSOT-23
TEMPERATURE RANGE
–40°C to 85°C
–40°C to 125°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/
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 3.6V unless otherwise specified.
SYMBOL
I
VFB
I
PK
V
FB
ΔV
FB
V
LOADREG
V
IN
I
S
PARAMETER
Feedback Current
Peak Inductor Current
Regulated Feedback Voltage
Reference Voltage Line Regulation
Output Voltage Load Regulation
Input Voltage Range
Input DC Bias Current
Pulse-Skipping Mode
Burst Mode Operation
Shutdown
Oscillator Frequency
SYNC Frequency Range
R
DS(ON)
of P-Channel FET
R
DS(ON)
of N-Channel FET
SW Leakage
I
SW
= 100mA
I
SW
= –100mA
V
RUN
= 0V, V
SW
= 0V or 5.5V, V
IN
= 5.5V
(Note 5)
V
FB
= 0.63V, Mode = High, I
LOAD
= 0A
V
FB
= 0.63V, Mode = Low, I
LOAD
= 0A
V
RUN
= 0V, V
IN
= 5.5V
V
FB
= 0.6V
l
l
l
ELECTRICAL CHARACTERISTICS
CONDITIONS
l
MIN
1.0
l
l
l
l
TYP
1.5
0.6
0.6
0.04
0.04
0.5
MAX
±30
2.0
0.612
0.618
0.4
0.8
5.5
UNITS
nA
A
V
V
%/V
%/V
%
V
μA
μA
μA
MHz
MHz
Ω
Ω
μA
3560fb
V
IN
= 3V, V
FB
= 0.5V, Duty Cycle < 35%
(Note 4)
V
IN
= 2.5V to 5.5V (Note 4)
E Grade
I Grade
E Grade
I Grade
0.588
0.582
2.5
200
16
0.1
1.8
1
0.23
0.21
±0.01
2.25
300
30
1
2.7
3
0.35
0.35
±1
f
OSC
f
SYNC
R
PFET
R
NFET
I
LSW
2
LTC3560
ELECTRICAL CHARACTERISTICS
SYMBOL
V
RUN
I
RUN
V
SYNC/MODE
I
SYNC/MODE
t
SOFTSTART
PARAMETER
RUN Threshold
RUN Leakage Current
SYNC/MODE Threshold
SYNC/MODE Leakage Current
Soft-Start Time
V
FB
from 10% to 90% Full Scale
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 3.6V unless otherwise specified.
CONDITIONS
l
l
l
l
MIN
0.3
0.3
0.6
TYP
1
±0.01
1.0
±0.01
0.9
MAX
1.5
±1
1.5
±1
1.2
UNITS
V
μA
V
μA
ms
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 LTC3560E is guaranteed to meet performance specifications
from 0°C to 85°C. Specifications over the –40°C to 85°C operating
temperature range are assured by design, characterization and correlation
with statistical process controls. The LTC3560I is guaranteed to meet
specified performance specifications over the full –40°C to 125°C
operating temperature range.
Note 3:
T
J
is calculated from the ambient temperature T
A
and power
dissipation P
D
according to the following formula:
LTC3560: T
J
= T
A
+ (P
D
)(250°C/W)
Note 4:
The LTC3560 is tested in a proprietary test mode that connects V
FB
to the output of the error amplifier.
Note 5:
Dynamic supply current is higher due to the gate charge being
delivered at the switching frequency.
Note 6:
Guaranteed by long-term current density limitations.
Note 7:
This IC includes overtemperature protection that is intended
to protect the device during momentary overload conditions. Junction
temperature will exceed 125°C when overtemperature protection is active.
Continuous operation above the specified maximum operating junction
temperature may impair device reliability.
TYPICAL PERFORMANCE CHARACTERISTICS
(From Figure 1a Except for the Resistive Divider Resistor Values)
Efficiency vs Input Voltage
100
95
90
EFFICIENCY (%)
EFFICIENCY (%)
85
80
75
70
65
60
55
50
V
OUT
= 1.8V
2.5
3
4
4.5
3.5
INPUT VOLTAGE (V)
5
5.5
3560 G01
Efficiency vs Output Current
100
100
90
80
EFFICIENCY (%)
70
60
50
40
30
V
IN
= 3.6V
V
IN
= 4.2V
V
IN
= 5.5V
1000
3560 G02
Efficiency vs Output Current
V
OUT
= 1.8V
I
OUT
= 100mA
I
OUT
= 10mA
I
OUT
= 1mA
I
OUT
= 900mA
90
80
70
60
50
40
30
20
10
V
OUT
= 3.3V
I
OUT
= 0.1mA
20
10
0
0.1
0
0.1
V
IN
= 2.7V
V
IN
= 3.6V
V
IN
= 4.2V
V
IN
= 5.5V
10
100
1
OUTPUT CURRENT (mA)
1000
3560 G03
1
10
100
OUTPUT CURRENT (mA)
3560fb
3
LTC3560
TYPICAL PERFORMANCE CHARACTERISTICS
(From Figure 1a Except for the Resistive Divider Resistor Values)
Efficiency vs Output Current
100
90
80
EFFICIENCY (%)
70
60
50
40
30
20
10
0
0.1
V
IN
= 2.7V
V
IN
= 3.6V
V
IN
= 4.2V
1
10
100
OUTPUT CURRENT (mA)
1000
3560 G04
Efficiency vs Output Current
100
90
80
EFFICIENCY (%)
70
60
50
40
30
20
10
V
OUT
= 1.8V
0
1
0.1
10
100
OUTPUT CURRENT (mA)
V
IN
= 4.2V
V
IN
= 3.6V
1000
3560 G05
Reference Voltage
vs Temperature
0.615
V
IN
= 3.6V
V
OUT
= 1.3V
Burst Mode OPERATION
0.610
REFERENCE VOLTAGE (V)
0.605
0.600
0.595
0.590
PULSE SKIP MODE
0.585
–50 –25
50
25
75
0
TEMPERATURE (°C)
100
125
3560 G06
Oscillator Frequency
vs Temperature
2.50
2.45
OSCILLATOR FREQUENCY (MHz)
2.40
2.35
2.30
2.25
2.20
2.15
2.10
2.05
2.00
–50
1.8
–25
50
25
0
75
TEMPERATURE (°C)
100
125
V
IN
= 3.6V
OSCILLATOR FREQUENCY (MHz)
2.4
2.3
Oscillator Frequency
vs Supply Voltage
1.84
1.83
OUTPUT VOLTAGE (V)
1.82
1.81
Output Voltage vs Load Current
V
IN
= 3.6V
2.2
2.1
2.0
1.9
Burst Mode OPERATION
1.80
1.79
1.78
PULSE SKIP MODE
2
2.5
3
4.5 5
3.5 4
INPUT VOLTAGE (V)
5.5
6
0
200
400
600
800
LOAD CURRENT (mA)
1000
1200
3560 G07
3560 G08
3560 G09
R
DS(ON
) vs Input Voltage
0.40
0.35
0.30
R
DS(0N)
(Ω)
MAIN SWITCH
0.25
SYNCHRONOUS
SWITCH
0.20
0.15
0.10
0
1
4
3
5
2
INPUT VOLTAGE (V)
6
7
3560 G10
R
DS(ON)
vs Temperature
0.40
V
IN
= 3.6V
DYNAMIC SUPPLY CURRENT (μA)
0.35
0.30
R
DS(ON)
(Ω)
0.25
0.20
0.15
0.10
0.05
0
–50 –25
0
SYNCHRONOUS SWITCH
MAIN SWITCH
75
50
25
TEMPERATURE (°C)
100
125
0
V
IN
= 4.2V
V
IN
= 2.7V
300
250
200
150
100
50
Dynamic Supply Current
V
OUT
= 1.2V
I
LOAD
= 0A
PULSE SKIPPING MODE
Burst Mode OPERATION
2
2.5
3
4.5 5
3.5 4
INPUT VOLTAGE (V)
5.5
6
3560 G11
3560 G12
3560fb
4
LTC3560
TYPICAL PERFORMANCE CHARACTERISTICS
(From Figure 1a Except for the Resistive Divider Resistor Values)
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