FEATURES
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LTC3401
1A, 3MHz Micropower
Synchronous Boost Converter
DESCRIPTIO
The LTC
®
3401 is a high efficiency, fixed frequency, step-
up DC/DC converter that operates from an input voltage
below 1V. The device includes a 0.16Ω N-channel MOSFET
switch and a 0.18Ω P-channel synchronous rectifier.
Switching frequencies up to 3MHz are programmed with
an external timing resistor and the oscillator can be
synchronized to an external clock. An external Schottky
diode is optional but will slightly improve efficiency.
Quiescent current is only 38μA in Burst Mode operation,
maximizing battery life in portable applications. Burst
Mode operation is user controlled and can be enabled by
driving the MODE/SYNC pin high. If the MODE/SYNC pin
has either a clock or is driven low, then fixed frequency
switching is enabled.
Other features include 1μA shutdown, antiringing control,
open-drain power good output, thermal shutdown and
current limit. The LTC3401 is available in the 10-lead
thermally enhanced MSOP package. Higher current appli-
cations should use the 2A rated LTC3402 synchronous
boost converter. Applications that require V
OUT
< 2.6V
should use the LTC3423.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
Burst Mode and OPTI-LOOP are registered trademarks of Linear Technology Corporation.
Synchronous Rectification: Up to 97% Efficiency
1A Switch Current Rating
Fixed Frequency Operation Up to 3MHz
Wide Input Range: 0.5V to 5.5V (Operating)
Very Low Quiescent Current: 38μA (Burst Mode
®
Operation)
2.6V to 5.5V Adjustable Output Voltage
0.85V (Typ) Start-Up Voltage
No External Schottky Diode Required (V
OUT
< 4.3V)
Synchronizable Switching Frequency
Burst Mode Enable Control
Antiringing Control Reduces Switching Noise
PGOOD Output
OPTI-LOOP
®
Compensation
Very Low Shutdown Current: < 1μA
Small 10-Pin MSOP Package
APPLICATIO S
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Pagers
Handheld Instruments
Cordless Phones
Wireless Handsets
GPS Receivers
Battery Backup
CCFL Backlights
TYPICAL APPLICATION
All-Ceramic-Capacitor 2-Cell to 3.3V at 500mA Step-Up Converter
V
IN
= 1.8V to 3V
L1
4.7μH
V
OUT
3.3V
500mA
SW
V
OUT
4
7
8
9
5
C3
470pF
R5
82k
C4
4.7pF
R1
549k
EFFICIENCY (%)
100
3
10
LTC3401
V
IN
SHDN
R2
909k
Burst Mode
90 OPERATION
80
70
1MHz
FIXED
FREQUENCY
+
2
CELLS
2
6
MODE/SYNC FB
PGOOD
R
t
V
C
GND
C2
22μF
60
50
40
30
20
10
0
C1
4.7μF
1
R
t
30.1k
V
IN
= 2.4V WITH SCHOTTKY
0.1
1
10
I
OUT
(mA)
100
1000
3401 TA02
0 = FIXED FREQUENCY
1 = Burst Mode OPERATION
C1: TAIYO YUDEN JMK212BJ475MG
C2: TAIYO YUDEN JMK325BJ226MM
L1: SUMIDA CD43-4R7M
3404 TA01
U
U
U
Efficiency
3401fb
1
LTC3401
ABSOLUTE
(Note 1)
AXI U
RATI GS
PACKAGE/ORDER I FOR ATIO
TOP VIEW
R
t
MODE
V
IN
SW
GND
1
2
3
4
5
10
9
8
7
6
SHDN
V
C
FB
V
OUT
PGOOD
V
IN
, V
OUT
Voltages ...................................... – 0.5V to 6V
SW Voltage ................................................. – 0.5V to 6V
V
C
, R
t
Voltages ......................... – 0.5V to (V
OUT
+ 0.3V)
PGOOD, SHDN, FB, MODE Voltages ........... – 0.5V to 6V
Operating Temperature Range (Note 2) .. – 40°C to 85°C
Storage Temperature Range ................. – 65°C to 125°C
Lead Temperature (Soldering, 10 sec).................. 300°C
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/
ORDER PART
NUMBER
LTC3401EMS
MS PART MARKING
LTPG
MS PACKAGE
10-LEAD PLASTIC MSOP
T
JMAX
= 125°C
θ
JA
= 130°C/ W 1 LAYER BOARD
θ
JA
= 100°C/ W 4 LAYER BOARD
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
The
●
denotes specifications that apply over the full operating temperature range, otherwise specifications are at T
A
= 25°C.
V
IN
= 1.2V, V
OUT
= 3.3V unless otherwise noted.
PARAMETER
Minimum Start-Up Voltage
Minimum Operating Voltage
Output Voltage Adjust Range
Feedback Voltage
Feedback Input Current
Quiescent Current—Burst Mode Operation
Quiescent Current—SHDN
Quiescent Current—Active
NMOS Switch Leakage
PMOS Switch Leakage
NMOS Switch On Resistance
PMOS Switch On Resistance
NMOS Current Limit
NMOS Burst Current Limit
Maximum Duty Cycle
Minimum Duty Cycle
Frequency Accuracy
MODE/SYNC Input High
MODE/SYNC Input Low
MODE/SYNC Input Current
Error Amp Transconductance
PGOOD Threshold
V
MODE/SYNC
= 5.5V
ΔI
= – 5μA to 5μA, V
C
= V
FB
Referenced to Feedback Voltage
–6
0.01
85
–9
– 12
R
t
= 15k
R
t
= 15k
●
●
●
●
CONDITIONS
I
LOAD
< 1mA
(Note 4)
●
●
●
MIN
TYP
0.85
MAX
1.0
0.5
5.5
UNITS
V
V
V
V
nA
μA
μA
μA
μA
μA
Ω
Ω
A
A
%
2.6
1.22
1.25
1
38
0.1
440
0.1
0.1
0.16
0.18
1
80
1.6
1.4
1.6
0.66
85
1.28
50
65
1
800
5
10
V
FB
= 1.25V
V
C
= 0V, MODE/SYNC = 3.3V (Note 3)
SHDN = 0V, Not Including Switch Leakage
V
C
= 0V, MODE/SYNC = 0V, R
t
= 300k (Note 3)
0
2
2.4
0.4
1
μmhos
%
2
U
%
MHz
V
V
μA
3401fb
W
U
U
W W
W
LTC3401
ELECTRICAL CHARACTERISTICS
The
●
denotes specifications that apply over the full operating temperature range, otherwise specifications are at T
A
= 25°C.
V
IN
= 1.2V, V
OUT
= 3.3V unless otherwise noted.
PARAMETER
PGOOD Low Voltage
PGOOD Leakage
SHDN Input High
SHDN Input Low
SHDN Input Current
Thermal Shutdown
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 LTC3401 is guaranteed to meet performance specifications
from 0°C to 70°C. Specifications over the –40°C to 85°C operating
V
SHDN
= 5.5V
0.01
170
CONDITIONS
I
PGOOD
= 1mA
V
OUT
= 1V, I
PGOOD
= 20μA
V
PGOOD
= 5.5V
V
SHDN
= V
IN
= V
OUT
1
0.4
1
MIN
TYP
0.1
0.1
0.01
MAX
0.2
0.4
1
UNITS
V
V
μA
V
V
μA
°C
temperature range are assured by design, characterization and correlation
with statistical process controls.
Note 3:
Current is measured into V
OUT
since the supply current is
bootstrapped to the V
OUT
pin and in the application will reflect to the input
supply by (V
OUT
/V
IN
) • I/ Efficiency. The outputs are not switching.
Note 4:
Once the output is started, the IC is not dependant upon the V
IN
supply.
TYPICAL PERFOR A CE CHARACTERISTICS
SW Pin and Inductor Current (I
C
)
in Discontinuous Mode. Ringing
Control Circuitry Eliminates High
Frequency Ringing
I
L
50mA/DIV
0A
SW
1V/DIV
Switching Waveform on SW Pin
50ns/DIV
U W
3401 G01
Transient Response 5mA to 50mA
V
OUT
100mV/DIV
SW
1V/DIV
50mA
I
OUT
0V
200ns/DIV
3401 G02
5mA
C
OUT
= 22μF
L = 3.3μH
f
OSC
= 1MHz
200μs/DIV
3401 G03
3401fb
3
LTC3401
TYPICAL PERFOR A CE CHARACTERISTICS
Transient Response 50mA to 500mA
V
OUT
AC
100mV/DIV
V
OUT
200mV/DIV
550mA
I
OUT
50mA
C
OUT
= 22μF
L = 3.3μH
f
OSC
= 1MHz
200μs/DIV
3401 G04
Converter Efficiency 1.2V to 3.3V
100
90
80
70
EFFICIENCY (%)
60
50
40
30
20
10
0
0.1
1
10
100
OUTPUT CURRENT (mA)
1000
3401 G07
300kHz
Burst Mode
OPERATION
3MHz
EFFICIENCY (%)
1MHz
60
50
40
30
20
10
0
0.1
EFFICIENCY (%)
Start-Up Voltage
vs I
OUT
500
T
A
= 25°C
14
12
OUTPUT CURRENT (mA)
400
EFFICIENCY LOSS (%)
300
8
6
4
2
0
0.2
CURRENT (A)
200
100
0
0.8
0.9
1
1.1
V
IN
(V)
1.2
1.3
1.4
3401 G09
4
U W
Burst Mode Operation
V
OUT
AC
100mV/DIV
Burst Mode Operation
SW
1V/DIV
SW
1V/DIV
V
IN
= 1.2V
5ms/DIV
V
OUT
= 3.3V
C
OUT
= 100μF
I
OUT
= 250μA
MODE/SYNC PIN = HIGH
3401 G05
V
IN
= 1.2V
200μs/DIV
V
OUT
= 3.3V
C
OUT
= 100μF
I
OUT
= 20mA
MODE/SYNC PIN = HIGH
3401 G06
Converter Efficiency 2.4V to 3.3V
100
90
80
70
300kHz
3MHz
1MHz
Burst Mode
OPERATION
Converter Efficiency 3.6V to 5V
100
90
80
70
60
50
40
30
20
10
1MHz
FIXED
FREQUENCY
Burst Mode OPERATION
1
10
100
OUTPUT CURRENT (mA)
1000
3401 G08
0
0.1
1
100
10
LOAD CURRENT (mA)
1000
3401
G10
Efficiency Loss Without Schottky
vs Frequency
T
A
= 25°C
Current Limit
1.80
1.75
1.70
1.65
1.60
1.55
1.50
1.45
10
0.6
1.0 1.4 1.8 2.2
FREQUENCY (MHz)
2.6
3.0
1.40
–55
–15
65
TEMPERATURE (°C)
25
105 125
3401 G12
3401 G11
3401fb
LTC3401
TYPICAL PERFOR A CE CHARACTERISTICS
EA FB Voltage
1.28
1.27
2.05
FREQUENCY (MHz)
VOLTAGE (V)
1.26
1.25
1.24
1.23
1.22
–55
RESISTANCE (Ω)
–15
65
TEMPERATURE (°C)
25
PMOS R
DS(ON)
0.30
V
OUT
= 3.3V
1.1
0.25
RESISTANCE (Ω)
VOLTAGE (V)
0.20
0.9
VOLTAGE (V)
0.15
0.10
0.05
–55
–15
65
TEMPERATURE (°C)
25
PGOOD Threshold
–7.0
–7.5
PERCENT FROM V
FB
(%)
–8.0
–8.5
40
CURRENT (μA)
–9.0
–9.5
VOLTAGE (V)
–10.0
–10.5
–11.0
–11.5
–12.0
–55
–15
65
TEMPERATURE (°C)
25
105 125
3401 G19
U W
Oscillator Frequency Accuracy
2.10
R
t
= 15k
0.30
NMOS R
DS(ON)
V
OUT
= 3.3V
0.25
0.20
2.00
0.15
1.95
0.10
105 125
3401 G13
1.90
–55
–15
65
TEMPERATURE (°C)
25
105 125
3401 G14
0.05
–55
–15
65
TEMPERATURE (°C)
25
105 125
3401 G22
Start-Up Voltage
1.10
1.05
1.0
1.00
0.95
0.90
0.85
0.80
0.75
0.7
0.70
0.65
105 125
3401 G16
Shutdown Threshold
0.8
0.6
–55
–15
65
TEMPERATURE (°C)
25
105 125
3401 G17
0.60
–55
–15
65
TEMPERATURE (°C)
25
105 125
3401 G18
Burst Mode Operation Current
44
42
2.50
2.45
2.40
2.35
2.30
2.25
2.20
2.15
2.10
32
30
–55
2.05
–15
65
TEMPERATURE (°C)
25
105 125
3401 G20
V
OUT
Turn-Off Voltage
38
36
34
2.00
–55
–15
65
TEMPERATURE (°C)
25
105 125
3401 G21
3401fb
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