FEATURES
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LTC3100
1.5MHz Synchronous Dual
Channel DC/DC Converter
and 100mA LDO
DESCRIPTION
The LTC
®
3100 combines a high efficiency 700mA syn-
chronous step-up converter, a 250mA synchronous
step-down converter and a 100mA LDO regulator. The
LTC3100 features a wide input voltage range of 0.65V to
5V. The step-down converter can be powered by the output
of the step-up converter or from a separate power source
between 1.8V and 5.5V. The LDO can also be used as a
sequencing switch on the output of the boost.
A switching frequency of 1.5MHz minimizes solution foot-
print by allowing the use of tiny, low profile inductors and
ceramic capacitors. The switching regulators use current
mode control and are internally compensated, reducing
external parts count. Each converter automatically transi-
tions to Burst Mode operation to maintain high efficiency
over the full load range. Burst Mode operation can be
disabled for low noise applications. The integrated LDO
provides a third low noise, low dropout supply.
Anti-ringing circuitry reduces EMI by damping the boost
inductor in discontinuous mode. Additional features
include shutdown current of under 1μA and overtem-
perature shutdown. The LTC3100 is housed in a 16-lead
3mm
×
3mm 0.75mm QFN package.
, LT, LTC, LTM and Burst Mode are registered trademarks of Linear Technology
Corporation. All other trademarks are the property of their respective owners.
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Extremely Compact Triple-Rail Solution
Burst Mode
®
Operation, I
Q
= 15μA
1.5MHz Fixed Frequency Operation
Power Good Indicators
700mA Synchronous Step-Up DC/DC
0.65V to 5V V
IN
Range
1.5V to 5.25V V
OUT
Range
94% Peak Efficiency
V
IN
> V
OUT
Operation
Output Disconnect
250mA Synchronous Step-Down DC/DC
1.8V to 5.5V V
IN
Range
0.6V to 5.5V V
OUT
Range
LDO (V
IN
Internally Tied to V
BST
)
0.6V to 5.25V V
OUT
Range
200mV Dropout Voltage at 100mA
Available in a 16-Lead 3mm
×
3mm QFN Package
APPLICATIONS
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Bar Code Readers
Medical Instruments
Low Power Portable Electronic Devices
TYPICAL APPLICATION
Two-Cell, Triple Output Converter
3.3μH
V
BATT
1.6V TO 3.2V
2.2μF
LTC3100
PGBST
V
LDO
102k
FBLDO
FF EN_BURST
BOOST
LDO
BUCK
OFF ON
OFF ON
OFF ON
MODE
4.7μH
RUNBST
RUNLDO
RUNBK
GND
SWBK
2M
FBBK
1M
PGBK
3100 TA01a
3.3V AT 100mA
V
BOOST
SWBST V
INBK
V
BST
FBBST
1.07M
BOOST_GOOD
3V AT 50mA
V
LDO
2.2μF
EFFICIENCY (%)
1.87M
10μF
2
1M
Efficiency and Power Loss
vs Load Current, V
IN
= 2.4V
100
90
80
70
60
50
40
30
BOOST
BUCK
PL, BOOST
PL, BUCK
0.1
1
10
100
LOAD CURRENT (mA)
1
10
100
POWER LOSS (mW)
1000
V
INBST
25.5k
1.8V AT 200mA
V
BUCK
10μF
1M
20
10
0
0.01
0.1
0.01
1000
3100 TA01b
BUCK_GOOD
3100fa
1
LTC3100
ABSOLUTE MAXIMUM RATINGS
(Note 1)
PIN CONFIGURATION
TOP VIEW
RUNBST
PGBST
V
INBST
MODE
12 FBBST
11 FBLDO
17
10 RUNLDO
9
5
V
INBK
6
PGBK
7
GND
8
RUNBK
FBBK
V
INBST
and V
INBK
Voltage .............................. –0.3 to 6V
SWBST, SWBK DC Voltage ............................. –0.3 to 6V
SWBST, SWBK Pulsed (< 100ns) Voltage ...... –0.3 to 7V
FBBST, FBBK, FBLDO, PGBST, PGBK Voltage . –0.3 to 6V
MODE, RUNBST, RUNBK, RUNLDO Voltage ... –0.3 to 6V
V
BST
, V
LDO
...................................................... –0.3 to 6V
Operating Temperature (Notes 2, 5) .........–40°C to 85°C
Storage Temperature Range...................–65°C to 125°C
16 15 14 13
SWBST 1
V
BST
2
V
LDO
3
SWBK 4
UD PACKAGE
16-LEAD (3mm 3mm) PLASTIC QFN
T
JMAX
= 125°C,
θ
JA
= 68°C/W, 4-LAYER BOARD
EXPOSED PAD (PIN 17) IS GND, MUST BE SOLDERED TO PCB (NOTE 6)
ORDER INFORMATION
LEAD FREE FINISH
LTC3100EUD#PBF
TAPE AND REEL
LTC3100EUD#TRPBF
PART MARKING
LDJR
PACKAGE DESCRIPTION
16-Lead (3mm
×
3mm) Plastic QFN
TEMPERATURE RANGE
–40°C to 85°C
Consult LTC Marketing for parts specified with wider operating temperature ranges.
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: STEP-UP CONVERTER
PARAMETER
Minimum Start-Up Voltage
Input Voltage Range
Output Voltage Adjust Range
Feedback Voltage
Feedback Input Current
Quiescent Current (V
IN
): Shutdown
Quiescent Current: Active
Quiescent Current: Burst Mode
Operation
N-Channel MOSFET Switch Leakage
Current
P-Channel MOSFET Switch Leakage
Current
FBBST = 1.2V
RUNBST = 0V, Not Including Switch Leakage, V
BST
= 0V, V
INBK
= 0V
Measured on V
BST
(Note 4), RUNBK = 0V, RUNLDO = 0V
Measured on V
BST
, FBBST > 1.25V
MODE = 1V, RUNLDO = 0V
MODE = 1V, RUNLDO = 1V
SWBST = 5V, V
BST
= 5V
SWBST = 0V, V
BST
= 5V
CONDITIONS
I
LOAD
= 1mA
After Start-Up (Minimum Voltage Is Load Dependent)
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l
The
l
denotes the specifications
which apply over the full operating temperature range. Extended commercial grade: –40°C to 85°C, V
INBST
= 1.2V, V
BST
= 3.3V,
T
A
= 25°C, unless otherwise noted.
MIN
0.5
1.5
1.182
1.200
1
0.01
300
15
28
0.1
0.1
TYP
0.65
MAX
0.90
5
5.25
1.218
50
1
500
25
45
5
10
UNITS
V
V
V
V
nA
μA
μA
μA
μA
μA
μA
3100fa
2
LTC3100
ELECTRICAL CHARACTERISTICS: STEP-UP CONVERTER
PARAMETER
N-Channel MOSFET Switch-On
Resistance
P-Channel MOSFET Switch-On
Resistance
N-Channel MOSFET Current Limit
Maximum Duty Cycle
Minimum Duty Cycle
Switching Frequency
RUNBST Input High Voltage
RUNBST Input Low Voltage
RUNBST Input Current
Soft-Start Time
PGBST Threshold, Falling
PGBST Hysteresis
PGBST Voltage Low
PGBST Leakage Current
Referenced to Feedback Voltage
Referenced to Feedback Voltage
5mA Load
PGBST = 5.5V
RUNBST = 1.2V
V
FBBST
= 1.15V
V
FBBST
= 1.3V
CONDITIONS
V
BST
= 3.3V
V
BST
= 3.3V
l
l
l
l
l
l
The
l
denotes the specifications
which apply over the full operating temperature range. Extended commercial grade: –40°C to 85°C, V
INBST
= 1.2V, V
BST
= 3.3V,
T
A
= 25°C, unless otherwise noted.
MIN
TYP
0.3
0.4
700
87
1.2
0.9
0.3
0.8
0.8
–8
3
65
0.01
10
2
850
90
0
1.5
1.8
MAX
UNITS
Ω
Ω
mA
%
%
MHz
V
V
μA
ms
%
%
mV
μA
ELECTRICAL CHARACTERISTICS: STEP-DOWN CONVERTER
PARAMETER
Input Voltage Range
Output Voltage Adjust Range
Feedback Voltage
Feedback Input Current
Quiescent Current: Shutdown
Quiescent Current: Active
Quiescent Current: Burst Mode Operation
N-Channel MOSFET Switch Leakage Current
P-Channel MOSFET Switch Leakage Current
N-Channel MOSFET Switch-On Resistance
P-Channel MOSFET Switch-On Resistance
P-Channel MOSFET Current Limit
Maximum Duty Cycle
Minimum Duty Cycle
Switching Frequency
FBBK < 590mV
FBBK > 610mV
FBBK = 600mV
Measured on V
INBK
, RUNBK = 0V, V
INBST
= 0V, V
BST
= 0V
Not Including Switch Leakage
Measured on V
INBK
(Note 4), RUNBST = 0V
Measured on V
INBK
, FBBK = 620mV, MODE = OPEN,
RUNBST = 0V
V
INBK
= SWBK = 5V
SWBK = 0V, V
INBK
= 5V
V
INBK
= 3.3V
V
INBK
= 3.3V
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l
l
The
l
denotes the
specifications which apply over the full operating temperature range. Extended commercial grade: –40°C to 85°C, V
INBK
= 3.3V,
T
A
= 25°C, unless otherwise noted.
CONDITIONS
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l
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MIN
1.8
0.61
590
TYP
MAX
5.5
5.5
UNITS
V
V
mV
nA
μA
μA
μA
μA
μA
Ω
Ω
mA
%
600
1
0.01
240
16
0.1
0.1
0.45
0.55
610
30
1
350
30
5
5
340
100
450
0
%
MHz
1.2
1.5
1.8
3100fa
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LTC3100
ELECTRICAL CHARACTERISTICS: STEP-DOWN CONVERTER
PARAMETER
RUNBK Input High Voltage
RUNBK Input Low Voltage
RUNBK Input Current
Soft-Start Time
PGBK Threshold, Falling
PGBK Hysteresis
PGBK Voltage Low
PGBK Leakage Current
Referenced to Feedback Voltage
Referenced to Feedback Voltage
5mA Load
PGBK = 5.5V
RUNBK = 1.2V
CONDITIONS
l
l
The
l
denotes the
specifications which apply over the full operating temperature range. Extended commercial grade: –40°C to 85°C, V
INBK
= 3.3V,
T
A
= 25°C, unless otherwise noted.
MIN
0.9
0.3
0.8
1.3
–8
3
65
0.01
10
2
TYP
MAX
UNITS
V
V
μA
ms
%
%
mV
μA
ELECTRICAL CHARACTERISTICS: LDO REGULATOR
PARAMETER
Input Voltage Range
Output Voltage Adjust Range
Feedback Voltage
Maximum Output Current
Feedback Input Current
Line Regulation
Load Regulation
Dropout Voltage
Ripple Rejection (PSRR)
Short-Circuit Current Limit
Soft-Start Time
RUNLDO Input High Voltage
RUNLDO Input Low Voltage
RUNLDO Input Current
Quiescent Current—Active
RUNLDO = 1.2V
RUNLDO = 3.3V, Measured on V
BST
RUNBST = RUNBK = 0V, V
INBK
= 0V
FBLDO = 600mV
V
IN
= 3.3V to 5.25V
From 10mA to 100mA Load
I
OUT
= 100mA
Frequency = 1.5MHz at I
LOAD
= 50mA, C
OUT
= 2.2μF (Note 3)
FBLDO < 582mV
(Note 3)
CONDITIONS
The
l
denotes the specifications which
apply over the full operating temperature range. Extended commercial grade: –40°C to 85°C, V
BST
= 3.3V, V
LDO
= 3V, T
A
= 25°C, unless
otherwise noted.
MIN
l
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TYP
MAX
5.25
5.25
UNITS
V
V
mV
mA
nA
%/ V
%
1.8
0.618
582
100
600
120
1
0.1
0.1
618
30
l
l
130
35
120
0.3
0.9
200
160
mV
dB
mA
ms
V
l
l
0.3
0.8
26
2
40
V
μA
μA
ELECTRICAL CHARACTERISTICS: COMMON CIRCUITRY
PARAMETER
MODE Input High Voltage
MODE Input Low Voltage
MODE Input Current
MODE = 0V
MODE = 5V
CONDITIONS
l
l
The
l
denotes the specifications
which apply over the full operating temperature range. Extended commercial grade: –40°C to 85°C, V
BST
or V
INBK
= 3.3V, T
A
= 25°C,
unless otherwise noted.
MIN
0.9
0.3
–3.3
1.7
–5
3
TYP
MAX
UNITS
V
V
μA
μA
3100fa
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LTC3100
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 LTC3100E is guaranteed to meet performance specifications
from 0°C to 85°C. Specifications over –40°C to 85°C operating
temperature range are assured by design, characterization and correlation
with statistical process controls.
Note 3:
Specification is guaranteed by design and not 100% tested in
production.
Note 4:
Current measurements are made when the output is not switching.
Note 5:
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 result in device degradation or failure.
Note 6:
Failure to solder the exposed backside of the package to the PC
board ground plane will result in a thermal resistance much higher than
68°C/W.
TYPICAL PERFORMANCE CHARACTERISTICS
Step-Up DC/DC Converter
Efficiency vs Load Current
and V
IN
for V
O
= 1.8V
100
90
80
EFFICIENCY (%)
70
60
50
40
30
20
10
0
0.01
0.1
V
IN
= 1.2V
V
IN
= 1.5V
PL, V
IN
= 1.2V
PL, V
IN
= 1.5V
1
10
100
LOAD CURRENT (mA)
0.1
1
10
100
POWER LOSS (mW)
EFFICIENCY (%)
1000
100
90
80
70
60
50
40
30
20
10
0
0.01
T
A
= 25°C, unless otherwise specified.
Efficiency vs Load Current
and V
IN
for V
O
= 3.3V
1000
100
POWER LOSS (mW)
10
1
V
IN
= 1.2V
V
IN
= 2.4V
V
IN
= 3V
PL, V
IN
= 1.2V
PL, V
IN
= 2.4V
PL, V
IN
= 3V
0.1
1
10
100
LOAD CURRENT (mA)
0.1
0.01
1000
0.01
1000
3100 G01
3100 G02
Efficiency vs Load Current
and V
IN
for V
O
= 5V
100
90
80
EFFICIENCY (%)
70
60
50
40
30
20
10
0
0.01
0.1
V
IN
= 1.8V
V
IN
= 2.4V
V
IN
= 3.6V
PL, V
IN
= 1.8V
PL, V
IN
= 2.4V
PL, V
IN
= 3.6V
1
10
100
LOAD CURRENT (mA)
1
10
100
POWER LOSS (mW)
EFFICIENCY (%)
1000
100
90
80
70
60
50
40
30
20
10
3.3V, 100mA Efficiency vs V
IN
0.1
0.01
1000
V
BST
= 3.3V AT 100mA
0
1.8 2 2.2 2.4 2.6 2.8 3 3.2 3.4 3.6 3.8 4 4.2
V
INBST
(V)
3100 G04
3100 G03
3100fa
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