LTC3458L
1
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FEATURES
DESCRIPTIO
U
APPLICATIO S
U
TYPICAL APPLICATIO
U
High Efficiency: Up to 95%
Inrush Current Limiting and Output Disconnect
Programmable Output Voltages up to 6V
1.5V to 6V Input Range
Programmable/Synchronizable Fixed Frequency
Operation up to 1.5MHz
Programmable Automatic Burst Mode
Operation
Current Mode Control with Programmable Soft-Start
Period and Peak Current Limit
0.2
N-Channel and 0.3 P-Channel Switches
Ultralow Quiescent Currents: 12
A Sleep, <1A in
Shutdown
12-Pin 4mm
3mm Thermally Enhanced DFN
Package
Point-of-Load Regulators
USB V
BUS
Power
Portable GPS
MP3 Players
1.7A, 1.5MHz Synchronous
Step-Up DC/DC Converter
with Output Disconnect
The LTC
3458L is a high efficiency, current mode, fixed
frequency, step up DC/DC converter with true output
disconnect and inrush current limiting. The LTC3458L is
rated for up to 6V output and includes a 0.2
N-channel
MOSFET switch and a 0.3
P-channel MOSFET synchro-
nous rectifier. The LTC3458L is well suited for battery
powered applications and includes programmable output
voltage, switching frequency and loop compensation. The
oscillator frequency can be set up to 1.5MHz or synchro-
nized to an external clock.
Quiescent current is only 12
A during Burst Mode opera-
tion maximizing battery life in portable applications. The
Burst Mode current threshold, peak current limit, and soft-
start are externally programmable. Other features include
<1
A shutdown current, antiringing control, and thermal
limit. The LTC3458L is available in a low profile (0.75mm),
4mm
3mm 12-pin DFN package.
Li-Ion to 5V at 1MHz
Li-Ion to 5V
OUT
V
IN
GND/PGND
SHDN
SYNC
R
T
I
LIM
SW
V
OUT
FB
COMP
SS
BURST
LTC3458L
Li Ion
3.1V TO 4.2V
2.2
F
7.4
H
ON OFF
200k
84.5k
133k
324k
33k
0.01
F
0.01
F
560pF
10pF
10pF
1M
22
F
X5R
V
OUT
5V
750mA
3458L TA01a
LOAD CURRENT (mA)
0.1
EFFICIENCY (%)
3.6 V
IN
POWER LOSS (mW)
100
95
90
85
80
75
70
65
60
1000
100
10
1
0.1
1
10
3458L TA01b
100
1000
4.2V
IN
3.1V
IN
POWER
LOSS
3.6V
IN
, LTC and LT are registered trademarks of Linear Technology Corporation.
Burst Mode is a registered trademark of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
Protected by U.S. Patents including 5481178, 6304066, 6580258, 5511131, 6498466
LTC3458L
2
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V
IN
, SS, SYNC Voltages ................................. 0.3 to 7V
BURST, SHDN, V
OUT
Voltages ....................... 0.3 to 7V
Operating Temperature Range
(Notes 2, 3) .........................................40
C to 85C
Storage Temperature Range ..................65
C to 125C
SW Voltage
DC ........................................................... 0.3V to 7V
Pulsed <100ns ........................................ 0.3V to 8V
ORDER PART
NUMBER
T
JMAX
= 125
C,
JA
= 45
C/W
LTC3458LEDE
ABSOLUTE AXI U
RATI GS
W
W
W
U
PACKAGE/ORDER I FOR ATIO
U
U
W
(Note 1)
ELECTRICAL CHARACTERISTICS
The
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25
C. V
IN
= 3.3V, V
OUT
= 5V, R
T
= 200k, unless otherwise noted.
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Minimum V
IN
Operating Voltage
T
A
= 0
C to 85C
1.4
1.5
V
T
A
= 40
C to 0C
1.4
1.7
V
Output Voltage Adjust Range
2
6
V
Feedback Voltage
0
C to 85C, V
OUT
= 3.3V
1.21
1.225
1.25
V
40
C to 0C
1.20
1.25
V
Undervoltage (Exit Burst Mode Operation)
Below Feedback Voltage
4
%
Feedback Input Current
V
FB
= 1.23V
1
50
nA
Quiescent Current Burst Mode Operation
V
IN
Current at 3.3V
12
30
A
V
OUT
Current at 5V
5
10
A
Quiescent Current Shutdown
V
IN
Current at 3.3V
0.5
1
A
V
OUT
Current at 0V
1
3
A
Quiescent Current Active
V
IN
Current Switching
1
3
mA
NMOS Switch Leakage
0.05
5
A
PMOS Switch Leakage
0.05
5
A
NMOS Switch On Resistance
V
OUT
= 5V
0.2
PMOS Switch On Resistance
V
OUT
= 5V
0.3
Fixed NMOS Current Limit
R
ILIM
= 84.5k
1.7
2.1
A
Maximum Duty Cycle
V
IN
= 3.3V, f
OSC
= 1MHz
80
90
%
Minimum Duty Cycle
0
%
Frequency Accuracy
R
T
= 200k
0.85
1
1.15
MHz
Error Amplifier Transconductance
60
A/V
Error Amplifier Source Current
7
A
Error Amplifier Sink Current
7
A
SYNC Input High
1.5
V
SYNC Input Low
0.35
V
Consult LTC Marketing for parts specified with wider operating temperature ranges.
12
11
10
9
8
7
1
2
3
4
5
6
V
OUT
BURST
SS
GND
COMP
FB
SW
V
IN
SYNC
SHDN
I
LIM
R
T
TOP VIEW
DE PACKAGE
12-LEAD (4mm
3mm) PLASTIC DFN
EXPOSED PAD IS PGND (PIN 13),
MUST BE SOLDERED TO PCB
13
DE PART MARKING
3458L
LTC3458L
3
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PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
SHDN Input High
1.25
V
SHDN Input Low
0.3
V
BURST Mode Peak Current (I
BURSTPEAK
)
R
ILIM
= 84.5k
0.55
A
BURST Threshold Voltage
1.10
V
The
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25
C. V
IN
= 3.3V, V
OUT
= 5V, R
T
= 200k, unless otherwise noted.
ELECTRICAL CHARACTERISTICS
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2: 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.
Note 3: The LTC3458LE is guaranteed to meet performance specifications
from 0
C to 70C. Specifications over the 40C to 85C operating
temperature range are assured by design, characterization and correlation
with statistical process controls.
TYPICAL PERFOR A CE CHARACTERISTICS
U
W
I
LIMIT
, I
BURSTPEAK
, I
ZERO
Currents
Burst Mode Quiescent Current
Maximum Load Current in Burst
Oscillator Programming Resistor
Current Limit Accuracy
Typical Burst Mode Threshold and
Hysteresis vs R
BURST
(T
A
= 25
C unless otherwise specified)
TEMPERATURE (
C)
TEMPERATURE (
C)
V
IN
(V)
40
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
CURRENT (
A)
10
15
60
3458L G03
3458L G01
3458L G02
5
0
15
10
35
85
20
CURRENT (mA)
2200
2000
1800
1600
1400
1200
1000
800
600
400
200
0
200
I
LIMIT
I
BURSTPEAK
I
ZERO
I
VIN
I
VOUT
V
IN
= 3.3V
V
OUT
= 5V
3458L G04
3458L G05
3458L G06
R
BURST
(k
)
50
CURRENT (mA)
200
300
100
150
250
160
140
120
100
80
60
40
20
0
V
IN
(V)
1.5
CURRENT (mA)
300
250
200
150
100
50
0
3.0
4.0
4.5
2.0
2.5
3.5
OSCILLATOR FREQUENCY (kHz)
400
RT (k
)
600
550
500
450
400
350
300
250
200
150
100
1200
600
800
1000
1400
OUT OF
BURST
INTO
BURST
3.3V
OUT
5V
OUT
R
ILIM
= 84.5k
45
1.85
CURRENT (A)
1.95
2.15
2.25
15
15
30
90
2.05
30
0
45
60
75
R
ILIMIT
= 84.5k
V
OUT
= 5V
L = 7.4
H
R
LIM
= 84.5k
LTC3458L
4
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TYPICAL PERFOR A CE CHARACTERISTICS
U
W
3458L G12
3458L G11
3458L G13
3458L G07
3458L G08
FREQUENCY (kHz)
500
EFFICIENCY (%)
95
93
91
89
87
85
1300
700
900
1100
1500
TEMPERATURE (
C)
40
R
DS(ON)
(
)
0.5
0.3
0.2
0.1
0
60
3458L G09
15
10
35
85
V
IN
(V)
MAX LOAD CURRENT (mA)
3458L G10
1600
1400
1200
1000
800
600
400
200
0
1.5
2.5
3.5
4.0
2.0
3.0
4.5
5.0
5.5
3.3V
OUT
5V
OUT
P-CHANNEL
N-CHANNEL
1.8 to 5.5V
IN
at 1MHz
R
ILIM
= 84.5k
V
IN
= 3.3V
V
OUT
= 5V
V
IN
= 3.3V
V
OUT
= 5V at 200mA
L = 7.4
H
TEMPERATURE (
C)
45
0.95
FREQUENCY (MHz)
0.97
1.01
1.03
1.05
15
15
30
90
0.99
30
0
45
60
75
TEMPERATURE (
C)
45
15
15
30
90
30
0
45
60
75
TEMPERATURE (
C)
45
15
15
30
90
30
0
45
60
75
0.5
VOLTAGE (V)
0.6
0.8
0.9
1.0
0.7
1.20
VOLTAGE (V)
1.21
1.23
1.24
1.25
1.22
TEMPERATURE (
C)
45
15
15
30
90
30
0
45
60
75
VOLTAGE (V)
1.5
1.4
1.3
1.2
1.1
1.0
0.9
0.8
OPERATING
SHUTDOWN
RT = 200k
Efficiency vs Frequency
Maximum Load Current
N-Channel and P-Channel R
DS(ON)
(T
A
= 25
C unless otherwise specified)
SHDN Pin Threshold and
Hysteresis
SYNC Pin Threshold
FB Voltage
Frequency Accuracy
LTC3458L
5
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TYPICAL PERFOR A CE CHARACTERISTICS
U
W
SW
1V/DIV
I
L
100mA/DIV
SW
1V/DIV
SW
5V/DIV
I
L
200mA/DIV
V
OUT
100mV/DIV
I
L
200mA/DIV
SW
5V/DIV
V
OUT
100mV/DIV
I
L
200mA/DIV
SS
200mV/DIV
V
OUT
2V/DIV
2V/DIV
V
IN
I
L
200mA/DIV
SW
2V/DIV
I
L
0.5A/DIV
0mA
500ns/DIV
1
s/DIV
500ns/DIV
50
s/DIV
2ms/DIV
2
s/DIV
V
IN
= 3.3V
V
OUT
= 5V
L = 7.4
H
V
IN
= 3.3V
V
OUT
= 5V
L = 7.4
H
V
IN
= 2.25V
V
OUT
= 5V
L = 7.4
H
R
ILIM
= 84.5k
V
IN
= 3.3V
V
OUT
= 5V
L = 7.4
H
C
OUT
= 22
F
C
FF
= 22pF*
R
ILIM
= 84.5k
*C
FF
: FEED FORWARD CAPACITOR CONECTED BETWEEN V
OUT
AND FB.
GND
0mA
0mA
0mA
0mA
V
IN
= 3.3V
V
OUT
= 5V
L = 7.4
H
C
OUT
= 22
F
C
FF
= 22pF
R
ILIM
= 84.5k
V
IN
= 3.3V
V
OUT
= 5V
L = 7.4
H
C
SS
= 0.1
F
3458L G14
3458L G15
3458L G16
3458L G17
3458L G18
3458L G19
Fixed Frequency (FF)
Discontinuous Current
Fixed Frequency (FF)
Continuous Current
Over-Current with 2A I
LIMIT
Burst Mode Operation
Burst Mode Operation Close-Up
Soft-Start into 20
Load
(T
A
= 25
C unless otherwise specified)
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