for low power portable devices. It provides three high
efficiency switching DC/DC converters which seamlessly
transition from battery to USB/wall adapter power when
available. A synchronous buck-boost regulator provides
complete flexibility, allowing operation from a single
Li-Ion/Polymer battery, 2 to 3 AA cells, a USB port or any
other power source operating from 1.8V to 5.5V.
Two always-alive outputs, a 50mA LDO and a 200mA MAX
output that tracks the higher voltage input supply, provide
power for critical functions or additional external regula-
tors. Flash memory cards can be directly powered from
the protected 100mA Hot Swap output. Pushbutton control
logic and a programmable-duration microprocessor reset
generator simplify interfacing to a microprocessor while
internal sequencing and independent enable pins provide
flexible power-up options. The LTC3101 is available in a low
profile (0.75mm) 24-lead 4mm
×
4mm QFN package.
L,
LT, LTC, LTM, Burst Mode, Linear Technology and the Linear logo are registered trademarks
and Hot Swap and PowerPath are trademarks of Linear Technology Corporation. All other
trademarks are the property of their respective owners.
n
n
n
n
n
n
n
n
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Low Loss PowerPath™ Control: Seamless,
Automatic Transition from Battery to USB or
Wall Adapter Power
Wide V
IN
Range: 1.8V to 5.5V
Buck-Boost V
OUT:
1.5V to 5.25V
Buck-Boost Generates 3.3V at 300mA for
V
IN
≥ 1.8V, 3.3V at 800mA for V
IN
≥ 3V
Dual 350mA Buck Regulators, V
OUT:
0.6V to V
IN
38μA Quiescent Current in Burst Mode
®
Operation
1.8V, 50mA Always-On LDO
Protected 100mA Hot Swap™ Output
Pushbutton On/Off Control
Current Limited 200mA MAX Output
Programmable Power-Up Sequencing
24-lead 4mm
×
4mm
×
0.75mm QFN Package
APPLICATIONS
n
n
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Ultra-Portable Digital Video Cameras
Personal Handheld GPS Navigators
Portable Medical Instruments
TYPICAL APPLICATION
2 AA
CELLS
+
10μF
4.7μH
BAT1 BAT2 SW3A
USB1
USB2
C
RS
0.1μF
DIS ENA
ON/OFF
PWRKEY
PBSTAT
PWM
PWRON
RESET
GND
SW1
ENA1
ENA2
ENA3
SW2
LTC3101
FB2
SW3B OUT3
FB3
HSO
MAX
LDO
10μF
1M
V
OUT3
= 3.3V
300mA FOR V
IN
≥ 1.8V
800mA FOR V
IN
≥ 3V
Efficiency vs V
BAT
96
94
EFFICIENCY (%)
92
90
88
86
BUCK2
I
OUT
= 150mA
BUCK1
I
OUT
= 150mA
BUCK-BOOST
I
OUT
= 150mA
USB/WALL
ADAPTER
4.3V TO 5.5V
221k
Hot Swap OUTPUT: 3.3V AT 100mA
TRACKING OUTPUT: 200mA
1.8V AT 50mA
4.7μF
4.7μH
V
OUT2
1.8V
10μF 350mA
221k
110k
4.7μH
221k
10μF
V
OUT1
1.5V
350mA
10μF
μP
84
1.5
2.5
3.5
V
BAT
(V)
4.5
5.5
3101 TA01b
FB1
147k
3101 TA01a
3101fb
1
LTC3101
ABSOLUTE MAXIMUM RATINGS
(Note 1)
PIN CONFIGURATION
TOP VIEW
SW3B
ENA2
ENA1
ENA3
18 HSO
17 OUT3
25
GND
16 USB2
15 SW3A
14 BAT2
13
RESET
7
FB3
8
PWRKEY
9 10 11 12
PBSTAT
LDO
MAX
C
RS
FB1
FB2
V
BAT1
, V
BAT2
, V
USB1
, V
USB2
......................... –0.3V to 6V
V
SW1
, V
SW2
, V
SW3A
, V
SW3B
DC............................................................ –0.3V to 6V
Pulsed (<100ns) ...................................... –1.0V to 7V
Voltage (All Other Pins)................................ –0.3V to 6V
Operating Temperature Range (Note 2).... –40°C to 85°C
Maximum Junction Temperature (Note 5)............. 125°C
Storage Temperature Range................... –65°C to 150°C
24 23 22 21 20 19
PWM 1
SW1 2
BAT1 3
USB1 4
SW2 5
PWRON 6
UF PACKAGE
24-LEAD (4mm
×
4mm) PLASTIC QFN
T
JMAX
= 125°C,
θ
JA
= 37°C/W
EXPOSED PAD (PIN 25) IS GND, MUST BE SOLDERED TO PCB
ORDER INFORMATION
LEAD FREE FINISH
LTC3101EUF#PBF
TAPE AND REEL
LTC3101EUF#TRPBF
PART MARKING
3101
PACKAGE DESCRIPTION
24-Lead (4mm
×
4mm) Plastic QFN
TEMPERATURE RANGE
–40°C to 85°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/
ELECTRICAL CHARACTERISTICS
PARAMETER
Input Operating Voltage
Undervoltage Lockout Threshold
Input Quiescent Current in Standby
Input Quiescent Current in Burst Mode Operation
Oscillator Frequency
Buck Converter 1
Feedback Voltage (FB1 Pin)
Feedback Pin Input Current (FB1 Pin)
P-Channel Current Limit
Maximum Duty Cycle
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
USB1
= V
USB2
= V
BAT1
= V
BAT2
= 3V and V
OUT3
= 3.3V, unless
otherwise noted.
CONDITIONS
Battery Powered
USB Powered
Battery Powered, V
BAT
Rising
USB Powered, V
USB
Rising
V
PWRON
= 0V, V
PWRKEY
= 3V
All Converters Enabled, V
FB1
= V
FB2
= V
FB3
= 0.66V
l
l
l
l
l
l
MIN
1.8
1.8
TYP
MAX
5.5
5.5
UNITS
V
V
V
V
μA
μA
1.7
1.7
15
38
1.02
583
440
440
1.27
596
1
540
540
1.8
1.8
1.52
609
50
MHz
mV
nA
mA
mA
%
3101fb
Battery Powered (Note 3)
USB Powered (Note 3)
l
100
2
LTC3101
ELECTRICAL CHARACTERISTICS
PARAMETER
Minimum Duty Cycle
ENA1 Input Logic Threshold
ENA1 Pull-Down Resistance
N-Channel Switch Resistance
P-Channel Switch Resistance
N-Channel Switch Leakage
P-Channel Switch Leakage
Power Good Threshold
Power Good Hysteresis
Buck Converter 2
Feedback Voltage (FB2 Pin)
Feedback Pin Input Current (FB2 Pin)
P-Channel Current Limit
Maximum Duty Cycle
Minimum Duty Cycle
ENA2 Input Logic Threshold
ENA2 Pull-Down Resistance
N-Channel Switch Resistance
P-Channel Switch Resistance
N-Channel Switch Leakage
P-Channel Switch Leakage
Power Good Threshold
Power Good Hysteresis
Buck-Boost Converter
Operating Output Voltage
Feedback Voltage (FB3 Pin)
Feedback Pin Input Current (FB3 Pin)
Inductor Current Limit
Reverse Inductor Current Limit
Burst Mode Inductor Current Limit
Maximum Duty Cycle
Minimum Duty Cycle
ENA3 Input Logic Threshold
ENA3 Pull-Down Resistance
N-Channel Switch Resistance
P-Channel Switch Resistance
V
PWRON
= 3V or V
PWRKEY
= 0V
Switch B (From SW3A to GND)
Switch C (From SW3B to GND)
Switch A´ (From BAT2 to SW3A)
Switch A (From USB2 to SW3A)
Switch D (From OUT3 to SW3B)
BAT or USB Powered (Note 3)
(Note 3)
(Note 3)
Percentage of Period SW3B is Low in Boost Mode
Percentage of Period SW3A is High in Buck Mode
l
l
l
l
l
l
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
USB1
= V
USB2
= V
BAT1
= V
BAT2
= 3V and V
OUT3
= 3.3V, unless
otherwise noted.
CONDITIONS
l
l
MIN
0.3
TYP
0.7
4.0
0.34
0.55
0.58
0.1
0.1
MAX
0
1.0
UNITS
%
V
MΩ
Ω
Ω
Ω
V
PWRON
= 3V or V
PWRKEY
= 0V
Battery Powered
USB Powered
V
SW1
= V
USB1,2
= V
BAT1,2
= 5.5V
V
SW1
= 0V, V
USB1,2
= V
BAT1,2
= 5.5V
V
FB1
Falling
l
5
10
–5
μA
μA
%
%
–11
–8
2.5
583
440
440
596
1
540
540
609
50
mV
nA
mA
mA
%
Battery Powered (Note 3)
USB Powered (Note 3)
l
l
l
100
0
0.3
0.7
4.0
0.34
0.55
0.58
0.1
0.1
5
10
–5
1.0
%
V
MΩ
Ω
Ω
Ω
μA
μA
%
%
V
PWRON
= 3V or V
PWRKEY
= 0V
Battery Powered
USB Powered
V
SW2
= V
USB1,2
= V
BAT1,2
= 5.5V
V
SW2
= 0V, V
USB1,2
= V
BAT1,2
= 5.5V
V
FB2
Falling
l
–11
–8
2.5
1.5
584
1.2
599
1
1.5
400
450
82
0.3
87
5.25
614
50
V
mV
nA
A
mA
mA
%
0
0.7
4.0
0.150
0.140
0.150
0.180
0.195
1.0
%
V
MΩ
Ω
Ω
Ω
Ω
Ω
3101fb
3
LTC3101
ELECTRICAL CHARACTERISTICS
PARAMETER
N-Channel Switch Leakage
P-Channel Switch Leakage
Power Good Threshold
Power Good Hysteresis
MAX Output
Current Limit
Switch Resistance
Load Dependent Supply Current
LDO Output
Output Voltage
Current Limit
Line Regulation
Load Regulation
Reverse Current in Shutdown
Load Dependent Supply Current
Dropout Voltage
Hot Swap Output
Switch Resistance
Switch Current Limit
Pushbutton Logic and μP Reset Generator
PBSTAT Deglitching Duration
PBSTAT Low Voltage
RESET
Low Voltage
C
RS
Pin Charging Current
C
RS
Pin Threshold Voltage
Logic Inputs
PWRKEY, PWRON, PWM Input Logic Threshold
PWRKEY Pull-Up Resistance
PWRON Pull-Down Resistance
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 LTC3101 is guaranteed to meet performance specifications
from 0°C to 85°C. Specifications over the –40°C to 85°C operating
temperature range are ensured by design, characterization and correlation
with statistical process controls.
Note 3:
Current measurements are performed when the LTC3101 is
not switching. The current limit values measured in operation will be
somewhat higher due to the propagation delay of the comparators.
l
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
USB1
= V
USB2
= V
BAT1
= V
BAT2
= 3V and V
OUT3
= 3.3V, unless
otherwise noted.
CONDITIONS
V
SW3A,B
= V
USB1,2
= V
BAT1,2
= V
OUT3
= 5.5V
V
SW3A,B
= 0V, V
USB1,2
= V
BAT1,2
= V
OUT3
= 5.5V
V
FB3
Falling
l
MIN
TYP
0.1
0.1
MAX
5
10
–5.5
UNITS
μA
μA
%
%
mA
Ω
Ω
μA/mA
–11.5
–8.5
2.5
V
MAX
= 2.0V
From BAT2 to MAX
From USB2 to MAX
l
200
300
0.890
0.930
1.0
I
LDO
= 1mA
V
LDO
= 1.0V
Input Voltage (V
MAX
) = 1.8V to 5.5V, I
LDO
= 1mA
I
LDO
= 1mA to 50mA
V
BAT1,2
= V
USB1,2
= 0V, V
LDO
= 1.8V
V
MAX
= 1.75V, I
LDO
= 10mA
l
l
1.755
50
1.800
110
0.1
0.9
0.1
12
25
0.730
1.845
V
mA
%
%
1
μA
μA/mA
mV
Ω
mA
ms
V
HSO
= 2.0V
l
100
15
150
24
20
20
50
50
1.1
1.224
1.0
I
PBSTAT
= 1mA
I
RESET
= 1mA
0.9
V
CRS
Rising
1.176
0.3
mV
mV
μA
V
V
kΩ
MΩ
1.0
1.200
0.7
400
4.0
Note 4:
The LTC3101 is tested in a proprietary non-switching test mode
that internally connects the error amplifiers in a closed-loop configuration.
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
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