FEATURES
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LTC3553-2
Micropower USB Power
Manager with Li-Ion Charger,
Always-On LDO and Buck Regulator
DESCRIPTION
The LTC
®
3553-2 is a micropower, highly integrated
power management and battery charger IC for single-cell
Li-Ion/Polymer battery applications. It includes a
PowerPath manager with automatic load prioritization,
a battery charger, an ideal diode and numerous internal
protection features. Designed specifically for USB applica-
tions, the LTC3553-2 power manager automatically limits
input current to a maximum of either 100mA or 500mA.
Battery charge current is automatically reduced such that
the sum of the load current and the charge current does
not exceed the selected input current limit. The LTC3553-2
also includes a synchronous buck regulator, an always-on
low dropout linear regulator (LDO), and a pushbutton
controller. With all supplies enabled in standby mode, the
quiescent current drawn from the battery is only 12μA.
The LTC3553-2 is available in a 3mm
×
3mm
×
0.75mm
20-pin QFN package.
L,
LT, LTC, LTM, Linear Technology, the Linear logo, and Burst Mode are registered trademarks
and PowerPath, Hot Swap, and Bat-Track are trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners. Protected by U.S. Patents,
including 6522118, 6700364, 5481178, 6304066, 6570372, 6580258, 7511390 and other
patents pending.
12μA Standby Mode Quiescent Current (All Outputs On)
Seamless Transition Between Input Power Sources:
Li-Ion/Polymer Battery and USB
240mΩ Internal Ideal Diode Provides Low Loss
PowerPath™
High Efficiency 200mA Buck Regulator
Always-On 150mA Low Dropout (LDO) Linear
Regulator
Pushbutton On/Off Control With System Reset
Full Featured Li-Ion/Polymer Battery Charger
Programmable Charge Current With Thermal Limiting
Instant-On Operation With Discharged Battery
3mm
×
3mm
×
0.75mm 20-Pin QFN Package
APPLICATIONS
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USB-Based Handheld Products
Portable Li-Ion/Polymer Based Electronic Devices
Wearable Electronics
Low Power Medical Devices
TYPICAL APPLICATION
4.35V TO 5.5V
USB INPUT
100k
V
BUS
10μF
LTC3553-2
NTC
100k
T
1.87k
BVIN
V
INLDO
PGOOD
HPWR
DIGITAL
CONTROL
SUSP
BUCK_ON
STBY
PBSTAT
SW
ON
BUCK_FB
ON/OFF
35532 TA01a
V
OUT
10μF
CHRG
SYSTEM
LOAD
18
BATTERY DRAIN CURRENT (μA)
Battery Drain Current
vs Temperature
V
BAT
= 3.8V
16 STBY = 3.8V
REGULATORS LOAD = 0mA
14
BUCK AND LDO ON
12
10
8
6
4
HARD RESET
0
–50 –30 –10 10 30 50 70 90 110 130
TEMPERATURE (°C)
2
ONLY LDO ON
PROG
BAT
+
Li-Ion
BATTERY
2.2μF
3.3V
150mA
4.7μF
LDO
2.05M
LDO_FB
649k
10μH
10pF
332k
649k
1.2V
200mA
10μF
35532 TA01b
35532f
1
LTC3553-2
ABSOLUTE MAXIMUM RATINGS
(Notes 1, 2, 3)
PIN CONFIGURATION
TOP VIEW
PROG
15 NTC
14
CHRG
21
GND
13 SW
12 BVIN
11 V
INLDO
6
STBY
7
BUCK_ON
8
BUCK_FB
9 10
LDO_FB
LDO
SUSP
V
BUS
V
OUT
BAT
V
BUS
, V
OUT
t < 1ms and Duty Cycle < 1% .................. –0.3V to 7V
Steady State............................................. –0.3V to 6V
BAT, NTC,
CHRG,
SUSP PBSTAT,
,
ON,
BUCK_FB, LDO_FB................................ –0.3V to 6V
BUCK_ON, STBY, HPWR, PGOOD, BVIN, V
INLDO
,
LDO (Note 4)....................................–0.3V to V
CC
+ 0.3V
I
BAT
.............................................................................1A
I
SW
(Continuous) .................................................300mA
I
LDO
(Continuous) ................................................175mA
I
CHRG
, I
PBSTAT
, I
PGOOD
............................................75mA
Operating Temperature Range.................. –40°C to 85°C
Junction Temperature ........................................... 110°C
Storage Temperature Range................... –65°C to 125°C
20 19 18 17 16
HPWR 1
PGOOD 2
PBSTAT 3
ON
4
GND 5
UD PACKAGE
20-LEAD (3mm
×
3mm) PLASTIC QFN
T
JMAX
= 110°C,
θ
JA
= 58.7°C/W
EXPOSED PAD (PIN 21) IS GND, AND MUST BE SOLDERED TO PCB GND
ORDER INFORMATION
LEAD FREE FINISH
LTC3553EUD-2#PBF
TAPE AND REEL
LTC3553EUD-2#TRPBF
PART MARKING
LGFJ
PACKAGE DESCRIPTION
20-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/
LTC3553 Options
PART NUMBER
LTC3553
LTC3553-2
LDO
ON/OFF Control
Always On
PGOOD
No
Yes
HARD RESET TIME
5 seconds
14 seconds
POWER MANAGER ELECTRICAL CHARACTERISTICS
The
l
denotes specifications that apply over the full operating temperature range, otherwise specifications are at T
A
= 25°C (Note 2),
V
BUS
= 5V, V
BAT
= 3.8V, HPWR = SUSP = BUCK_ON = 0V, R
PROG
= 1.87k, STBY = high, unless otherwise noted.
SYMBOL
I
BATQ
PARAMETER
Battery Drain Current (Note 5)
Buck and LDO Shutdown, Hard Reset
Buck and LDO Enabled
LDO Enabled, Buck Shutdown
Battery Drain Current, V
BUS
Available
V
BUS
Input Current
CONDITIONS
I
OUT
= I
SW
= I
LDO
= 0
V
BUS
= 0V, Hard Reset
V
BUS
= 0V, BUCK_ON = STBY = 3.8V
V
BUS
= 0V, BUCK_ON = 0V
V
BAT
= V
FLOAT
, Timer Timed Out
100mA, 500mA Modes
Charger On
Timer Timed Out
SUSP = 5V (Suspend Mode)
MIN
TYP
MAX
UNITS
No-Load Quiescent Currents
0.2
8
8
5
300
150
15
2
16
16
8
500
350
30
μA
μA
μA
μA
μA
μA
μA
35532f
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BATQC
I
BUSQ
2
LTC3553-2
POWER MANAGER ELECTRICAL CHARACTERISTICS
SYMBOL
I
BVINQ
PARAMETER
BVIN Input Current
Buck Shutdown
Buck Enabled, Standby Mode
Buck Enabled
V
INLDO
Input Current
LDO Shutdown (Hard Reset)
LDO Enabled
Input Supply Voltage
Total Input Current
V
BUS
Undervoltage Lockout
V
BUS
to BAT Differential Undervoltage
Lockout
Input Current Limit Power FET
On-Resistance (Between V
BUS
and V
OUT
)
V
BAT
Regulated Output Voltage
0 ≤ T
A
≤ 85°C
I
CHG
Constant-Current Mode Charge Current
R
PROG
= 1.87k, 0 ≤ T
A
≤ 85°C
PROG Pin Servo Voltage
V
PROG
V
PROG,TRKL
PROG Pin Servo Voltage in Trickle Charge V
BAT
< V
TRKL
h
PROG
I
TRKL
V
TRKL
ΔV
RECHRG
t
TERM
t
BADBAT
h
C/10
R
ON_CHG
T
LIM
NTC
V
COLD
V
HOT
V
DIS
I
NTC
Cold Temperature Fault Threshold
Voltage
Rising NTC Voltage
Hysteresis
75
34
l
1.2
–50
76
1.3
35
1.3
1.7
50
77
36
2.2
50
%V
BUS
%V
BUS
%V
BUS
%V
BUS
%V
BUS
mV
nA
Ratio of I
BAT
to PROG Pin Current
Trickle Charge Current
Trickle Charge Threshold Voltage
Recharge Battery Threshold Voltage
Safety Timer Termination Period
Bad Battery Termination Time
End-of-Charge Indication Current Ratio
Battery Charger Power FET
On-Resistance (Between V
OUT
and BAT)
Junction Temperature in Constant
Temperature Mode
V
BAT
< V
TRKL
V
BAT
Rising
V
BAT
Falling
Threshold Voltage Relative to V
FLOAT
Timer Starts when V
BAT
= V
FLOAT
– 50mV
V
BAT
< V
TRKL
(Note 6)
I
BAT
= 200mA
30
2.6
–75
3.2
0.4
0.085
4.179
4.165
380
HPWR = 0V (100mA)
HPWR = 5V (500mA)
Rising Threshold
Falling Threshold
Rising Threshold
Falling Threshold
l
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CONDITIONS
V
BUS
= 0V, V
BVIN
= 3.8V, I
SW
= 0 (Note 8)
BUCK_ON = 0V
BUCK_ON = STBY = 3.8V
BUCK_ON = 3.8V, STBY = 0V
V
BUS
= 0V, V
INLDO
= 3.8V, I
LDO
= 0 (Note 10)
0.01
0.1
4.35
80
400
3.5
0
90
450
3.8
3.6
200
50
350
1
1
5.5
100
500
3.9
300
μA
μA
V
mA
mA
V
mV
mV
mV
mΩ
The
l
denotes specifications that apply over the full operating temperature range, otherwise specifications are at T
A
= 25°C (Note 2),
V
BUS
= 5V, V
BAT
= 3.8V, HPWR = SUSP = BUCK_ON = 0V, R
PROG
= 1.87k, STBY = high, unless otherwise noted.
MIN
TYP
0.01
1.5
22
MAX
1
3
38
UNITS
μA
μA
μA
I
VINLDOQ
Input Power Supply
V
BUS
I
BUS(LIM)
V
UVLO
V
DUVLO
R
ON_ILIM
Battery Charger
V
FLOAT
4.2
4.2
400
1
0.1
750
40
2.9
2.75
–100
4
0.5
0.1
220
110
50
3
–125
5
0.63
0.115
4.221
4.235
420
V
V
mA
V
V
mA/mA
mA
V
V
mV
Hour
Hour
mA/mA
mΩ
°C
Hot Temperature Fault Threshold Voltage Falling NTC Voltage
Hysteresis
NTC Disable Threshold Voltage
NTC Leakage Current
Falling NTC Voltage
Hysteresis
V
NTC
= V
BUS
= 5V
35532f
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LTC3553-2
POWER MANAGER ELECTRICAL CHARACTERISTICS
SYMBOL
Ideal Diode
V
FWD
R
DROPOUT
I
MAX
V
IL
V
IH
R
PD
V
OL
I
CHRG
Forward Voltage Detection
Diode On-Resistance, Dropout
Diode Current Limit
Input Low Voltage
Input High Voltage
Internal Pull-Down Resistance
Output Low Voltage
Output Hi-Z Leakage Current
I
CHRG
= 5mA
V
BAT
= 4.5V, V
CHRG
= 5V
1.2
4
65
0
250
1
(Note 12)
I
OUT
= 200mA, V
BUS
= 0V
(Note 7)
15
240
1
0.4
mV
mΩ
A
V
V
MΩ
mV
μA
PARAMETER
CONDITIONS
The
l
denotes specifications that apply over the full operating temperature range, otherwise specifications are at T
A
= 25°C (Note 2),
V
BUS
= 5V, V
BAT
= 3.8V, HPWR = SUSP = BUCK_ON = 0V, R
PROG
= 1.87k, STBY = high, unless otherwise noted.
MIN
TYP
MAX
UNITS
Logic Inputs (HPWR, SUSP)
Logic Output (CHRG)
BUCK REGULATOR ELECTRICAL CHARACTERISTICS
SYMBOL
BVIN
PARAMETER
Input Supply Voltage
CONDITIONS
(Note 9)
V
OUT
Falling
V
OUT
Rising
The
l
denotes specifications that apply over the full operating temperature range, otherwise specifications are at T
A
= 25°C (Note 2).
BUCK_ON = V
OUT
= BVIN = 3.8V, unless otherwise noted.
MIN
l
2.7
2.5
0.955
–0.05
BUCK_ON = 0V
1.2
0.4
–1
BUCK_ON = 3.8V (Note 7)
BUCK_ON = 3.8V
I
SW
= 100mA
I
SW
= –100mA
BUCK_ON = 3.8V, V
BUCK_FB
Falling
BUCK_ON = 2.9V, I
SW
= 10mA, V
BUCK_FB
= 0.76V,
V
OUT
= 2.9V, BVIN = 2.9V
l
770
30
l
300
780
100
1.1
0.7
800
50
50
820
100
100
500
800
1
650
820
10
2.6
2.8
1.125
TYP
MAX
5.5
2.9
1.295
0.05
UNITS
V
V
V
MHz
μA
kΩ
V
V
μA
mA
mV
%
Ω
Ω
mV
mA
mV
V
OUT
UVLO V
OUT
Undervoltage Lockout
f
OSC
I
BUCK_FB
R
SW_PD
Oscillator Frequency
BUCK_FB Input Current (Note 8)
SW Pull-Down in Shutdown
Input High Voltage
Input Low Voltage
Input Current
Buck Regulator in Normal Operation (STBY Low)
I
LIM
V
BUCK_FB
D
MAX
R
P
R
N
Peak PMOS Current Limit
Regulated Feedback Voltage
Max Duty Cycle
R
DS(ON)
of PMOS
R
DS(ON)
of NMOS
Feedback Voltage Threshold
Short-Circuit Current
Standby Mode Dropout Voltage
Logic Input Pin (STBY)
Buck Regulator in Standby Mode (STBY High)
35532f
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LTC3553-2
LDO REGULATOR ELECTRICAL CHARACTERISTICS
SYMBOL
V
INLDO
PARAMETER
Input Voltage Range
CONDITIONS
(Note 9)
V
OUT
Falling
V
OUT
Rising
I
LDO
= 1mA (Note 10)
I
LDO
= 1mA, V
INLDO
= 1.65V to 5.5V (Note 10)
I
LDO
= 1mA to 150mA (Note 10)
–50
l
l
l
The
l
denotes specifications that apply over the full operating temperature range, otherwise specifications are at T
A
= 25°C (Note 2).
V
OUT
= V
INLDO
= 3.8V, unless otherwise noted.
MIN
1.65
2.5
780
2.6
2.8
800
0.7
0.025
50
300
160
220
180
0.2
10
260
350
280
150
TYP
MAX
5.5
2.9
820
UNITS
V
V
V
mV
mV/V
mV/mA
nA
mA
mA
mV
mV
mV
ms
kΩ
V
OUT
UVLO V
OUT
Undervoltage Lockout
V
LDO_FB
Regulated Feedback Voltage
V
LDO_FB
Line Regulation
V
LDO_FB
Load Regulation
I
LDO_FB
I
LDO_OC
I
LDO_SC
V
DROP
Feedback Pin Input Current
Available Output Current
Short-Circuit Output Current
Dropout Voltage (Note 13)
(Note 7)
I
LDO
= 150mA, V
INLDO
= 3.8V
I
LDO
= 150mA, V
INLDO
= 2.5V
I
LDO
= 75mA, V
INLDO
= 1.8V
t
LDO_SS
R
LDO_PD
Soft-Start Time
Output Pull-Down Resistance in Hard Reset
PUSHBUTTON INTERFACE ELECTRICAL CHARACTERISTICS
The
l
denotes specifications that apply over the full operating temperature range, otherwise specifications are at T
A
= 25°C (Note 2).
V
BAT
= 3.8V, unless otherwise noted.
SYMBOL
V
CC_PB
V
ON_TH
I
ON
R
PB_PU
PARAMETER
Pushbutton Operating Supply Range
ON
Threshold Rising
ON
Threshold Falling
ON
Input Current
Pushbutton Pull-Up Resistance
Input High Voltage
Input Low Voltage
Input Current
Status Output Pins (PBSTAT, PGOOD)
I
PBSTAT
V
PBSTAT
I
PGOOD
V
PGOOD
V
THPGOOD
PBSTAT Output High Leakage Current
PBSTAT Output Low Voltage
PGOOD Output High Leakage Current
PGOOD Output Low Voltage
PGOOD Threshold Voltage
V
PBSTAT
= 3V
I
PBSTAT
= 3mA
V
PGOOD
= 3V
I
PGOOD
= 3mA
(Note 14)
–1
0.1
–8
–1
0.1
1
0.4
1
0.4
μA
V
μA
V
%
V
ON
= V
CC
(Note 4)
Pull-Up to V
CC
(Note 4)
CONDITIONS
(Notes 4 , 9)
l
MIN
2.7
0.4
–1
200
1.2
TYP
MAX
5.5
1.2
1
UNITS
V
V
V
μA
kΩ
V
V
μA
Pushbutton Pin (ON)
400
650
Logic Input Pins (BUCK_ON)
0.4
–1
1
35532f
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