1
LTC4055
4055p
USB Power Controller
and Li-Ion Linear Charger
s
Charges Single Cell Li-Ion Batteries Directly from
USB Port
s
Load Dependent Charging Guarantees USB Input
Current Compliance
s
Automatic Battery Switchover When Input Supply
is Removed
s
Constant-Current/Constant-Voltage Operation with
Thermal Feedback to Maximize Charging Rate
Without Risk of Overheating
s
Selectable 100% or 20% Current Limit
(e.g., 500mA/100mA)
s
Low Loss Full PowerPath
TM
Control with Ideal Diode
Operation (Reverse Current Blocking)
s
Preset 4.2V Charge Voltage with 0.8% Accuracy
s
USB Compliant Suspend Mode
s
Programmable Charge Current and Termination Timer
s
Automatic Recharge
s
Soft-Start Limits Inrush Current
s
NTC Thermistor Input for Temperature Qualified
Charging
s
Tiny (4mm
4mm
0.8mm) QFN Package
The LTC
4055 is a USB power manager and Li-Ion battery
charger designed to work in portable battery-powered
applications. The part manages and limits the total current
used by the USB peripheral for operation and battery
charging. Depending on the state of the current select pin
(HPWR), total input current can be limited to either 100mA
or 500mA. The voltage drop from the USB supply or
battery to the USB peripheral is typically less than 100mV
at 400mA and 20mV at 80mA. Other management features
include: automatic switch over to battery when input is
removed, inrush current limiting, reverse current block-
ing, undervoltage lockout and thermal shutdown.
The LTC4055 includes a complete constant-current/con-
stant-voltage linear charger for single cell Li-ion batteries.
The float voltage applied to the battery is held to a tight
0.8% (typ) tolerance, and charge current is programmable
using an external resistor to ground. Fully discharged cells
are automatically trickle charged at 10% of the pro-
grammed current until the cell voltage exceeds 2.8V. Total
charge time is programmable by an external capacitor to
ground. When the battery drops 100mV below the float
voltage, automatic recharging of the battery occurs. Also
featured is an NTC thermistor input used to monitor
battery temperature while charging.
The LTC4055 is available in a 16-pin low profile
(4mm
4mm) QFN package.
s
Portable USB Devices: Cameras, MP3 Players, PDAs
, LTC and LT are registered trademarks of Linear Technology Corporation.
PowerPath is a trademark of Linear Technology Corporation.
+
IN1
IN2
V
NTC
NTC
WALL
SHDN
SUSP
HPWR
OUT
Li-Ion
CELL
10
F
1
10
F
TIMER PROG
LTC4055
CLPROG
GND
4055 TA01
TO LDOs,
REGs, ETC
BAT
CHRG
ACPR
0.1
F
100k
100k
SUSPEND USB POWER
500mA/100mA SELECT
5V (NOM)
FROM USB
CABLE V
BUS
I
LOAD
(mA)
0
CURRENT (mA)
300
400
600
500
I
IN
400
4055 TA02
200
100
100
0
100
200
300
600
I
BAT
(IDEAL DIODE)
500
I
BAT
CHARGING
I
LOAD
High Power/Full Charge
R
PROG
= R
CLPROG
= 100k
FEATURES
DESCRIPTIO
U
APPLICATIO S
U
TYPICAL APPLICATIO
U
Electrical Specifications Subject to Change
2
LTC4055
4055p
ORDER PART
NUMBER
(Notes 1, 2, 3, 4, 5)
Terminal Voltage
IN1, IN2, OUT, BAT ................................ 0.3V to 6V
NTC, V
NTC
, TIMER,
PROG, CLPROG ..................... 0.3V to (V
CC
+ 0.3V)
CHRG, HPWR, SUSP, SHDN,
WALL, ACPR .......................................... 0.3V to 6V
IN2 .......................................................... V
IN1
+ 0.1V
Pin Current (DC)
IN1, IN2, OUT, BAT (Note 7) ............................. 1.6A
Operating Temperature Range ............... 40
C to 85
C
Maximum Operating Junction Temperature......... 125
C
Reflow Peak Body Temperature ........................... 260
C
Storage Temperature Range ................ 65
C to 125
C
LTC4055EUF
T
JMAX
= 125
C,
JA
= 37
C/W
EXPOSED PAD IS GND (PIN 17)
MUST BE SOLDERED TO PCB
ABSOLUTE
M
AXI
M
U
M
RATINGS
W
W
W
U
PACKAGE/ORDER I
N
FOR
M
ATIO
N
W
U
U
The
q
indicates specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25
C. V
IN1
= V
IN2
= 5V, V
BAT
= 3.5V, HPWR = 5V, WALL = 0V,
R
PROG
= R
CLPROG
= 100k, unless otherwise noted.
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
16 15 14 13
5
6
7
8
TOP VIEW
17
UF PACKAGE
16-LEAD (4mm
4mm) PLASTIC QFN
9
10
11
12
4
3
2
1
IN2
BAT
OUT
IN1
TIMER
PROG
GND
CLPROG
NTC
VNTC
CHRG
ACPR
WALL
SHDN
SUSP
HPWR
4055
UF PART
MARKING
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
IN
Input Supply Voltage
IN1, IN2 and OUT
q
4.35
5.5
V
V
BAT
Input Voltage
BAT
q
4.3
V
I
IN
Input Supply Current
V
BAT
= 4.2V
q
0.8
1.6
mA
Suspend Mode
q
50
100
A
Suspend Mode, Wall = 2V, V
OUT
= 4.8V
0.2
mA
Shutdown
q
10
20
A
I
OUT
Output Supply Current
V
OUT
= 5V, V
IN1
= V
IN2
= 0V, V
BAT
= 4.2V
q
450
900
A
I
BAT
Battery Drain Current
V
BAT
= 4.2V, Charging Stopped
q
15
30
A
Suspend Mode
q
15
30
A
Shutdown
q
2.5
5
A
V
IN1
= V
IN2
= 0V, BAT Powers OUT, No Load
q
50
100
A
I
LIM(MAX)
Maximum Current Limit
(Note 8)
1
A
V
UVLO
Input or Output Undervoltage Lockout
V
IN
Powers Part, Rising Threshold
q
3.6
3.8
4
V
V
OUT
Powers Part, Rising Threshold
q
3.6
3.8
4
V
V
UVLO
Input or Output Undervoltage Lockout
V
IN
Rising V
IN
Falling or
125
mV
Hysteresis
V
OUT
Rising V
OUT
Falling
Current Limit
I
LIM
Current Limit
R
CLPROG
= 100k, HPWR = 5V
q
465
490
515
mA
R
CLPROG
= 100k, HPWR = 0V
q
89
97
105
mA
R
ON
ON Resistance V
IN
to V
OUT
HPWR = 5V, 400mA Load
0.2
HPWR = 0V, 80mA Load
0.2
V
PROG
Programming Pin Voltage
R
CLPROG
= R
PROG
= 100k
q
0.98
1.000
1.02
V
(PROG, CLPROG)
R
CLPROG
= R
PROG
= 50k
q
0.98
1.000
1.02
V
I
SS
Soft-Start Inrush Current
IN or OUT
5
mA/
s
V
CLEN
Input Current Limit Enable Threshold
V
IN
Rising
q
3.6
3.8
4
V
V
CLEN
Input Current Limit Enable Threshold
V
IN
Rising V
IN
Falling
125
mV
V
ALEN
Automatic Limit Enable Threshold
(V
IN
V
OUT
) V
IN
Rising
25
50
75
mV
Voltage
(V
IN
V
OUT
) V
IN
Falling
75
50
25
mV
3
LTC4055
4055p
The
q
indicates specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25
C. V
IN1
= V
IN2
= 5V, V
BAT
= 3.5V, HPWR = 5V, WALL = 0V,
R
PROG
= R
CLPROG
= 100k, unless otherwise noted.
ELECTRICAL CHARACTERISTICS
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Battery Charger
V
FLOAT
Regulated Output Voltage
(0
C to 85
C)
4.165
4.200
4.235
V
q
4.158
4.200
4.242
V
I
BAT
Current Mode Charge Current
R
PROG
= 100k, HPWR = 5V, No Load
q
445
485
525
mA
R
PROG
= 100k, HPWR = 0V, No Load
q
55
80
105
mA
R
PROG
= 100k, V
OUT
= 5V, V
IN
= 0V,
q
445
485
525
mA
V
WALL
= 2V
R
PROG
= 50k, HPWR = 5V, No Load
q
900
980
1060
mA
R
PROG
= 50k, V
OUT
= 5V, V
IN
= 0V,
q
900
980
1060
mA
V
WALL
= 2V
I
BAT(MAX)
Maximum Charge Current
(Note 8)
1
A
I
B
/
I
O
Charge Current Load Dependency
I
BAT
/
I
OUT
, I
OUT
= 100mA
q
0.95
1
1.05
mA/mA
I
TRKL
Trickle Charge Current
V
BAT
= 2V, R
PROG
= 100k
30
45
60
mA
V
TRKL
Trickle Charge Threshold Voltage
V
BAT
Rising
q
2.7
2.85
3
V
V
CENI
Input Charger Enable Threshold
(V
IN
V
BAT
) High to Low
70
mV
Voltage
(V
IN
V
BAT
) Low to High
80
mV
V
CENO
Output Charger Enable Threshold
(V
OUT
V
BAT
) High to Low
70
mV
Voltage
(V
OUT
V
BAT
) Low to High
80
mV
V
UVCL
Input/Output Undervoltage Current
I
BAT
= I
CHG
/2
q
4.23
4.3
4.37
V
Limit
V
RECHRG
Recharge Battery Threshold Voltage
V
FLOAT
V
RECHRG
q
65
100
135
mV
t
TIMER
TIMER Accuracy
C
TIMER
= 0.1
F
10
%
Recharge Time
Percent of Total Charge Time
50
%
Low-Battery Trickle Charge Time
Percent of Total Charge Time, V
BAT
< 2.8V
25
%
T
LIM
Junction Temperature in Constant
105
C
Temperature Mode
Ideal Diode
R
FWD
On Resistance, V
ON
Regulation
V
BAT
= 3.5V, 100mA Load
0.1
R
DIO,ON
On Resistance V
BAT
to V
OUT
V
BAT
= 3.5V, 600mA Load
0.2
V
FWD
Voltage Forward Drop (V
BAT
V
OUT
)
V
BAT
= 3.5V, 5mA Load
q
10
30
50
mV
V
BAT
= 3.5V, 100mA Load
55
mV
V
BAT
= 3.5V, 600mA
120
mV
V
OFF
Diode Disable Battery Voltage
V
BAT
Falling
2.8
V
I
FWD
Load Current Limit for V
ON
Regulation
V
IN
= 3.5V
550
mA
I
MAX
Diode Current Limit
V
BAT
= 3.5V, V
OUT
= 2.8V, Pulsed with
1.4
1.8
2.2
A
10% Duty Cycle
Logic
V
OL
Output Low Voltage (CHRG, ACPR)
I
SINK
= 5mA
q
0.2
0.4
V
V
IH
Enable Input High Voltage
SUSP, SHDN, HPWR Pin Low to High
q
1.2
V
V
IL
Enable Input Low Voltage
SUSP, SHDN, HPWR Pin High to Low
q
0.4
V
I
PULLDN
Logic Input Pull-Down Current
SUSP, SHDN, HPWR
2
A
V
CHG,SD
Charger Shutdown Threshold Voltage
TIMER Falling
q
0.15
0.4
V
on TIMER
I
CHG,SD
Charger Shutdown Pull-Up Current
V
TIMER
= 0V
q
2
4
A
on TIMER
V
WALL
Wall Input Threshold Voltage
V
WALL
Rising Threshold
q
0.98
1.000
1.02
V
V
WALL,HYS
Wall Input Hysteresis
V
WALL
Rising V
WALL
Falling Threshold
35
mV
I
WALL
Wall Input Leakage Current
V
WALL
= 1V
0
50
nA
4
LTC4055
4055p
Note 1: Absolute Maximum Ratings are those beyond which the life of a
device may be impaired.
Note 2: V
CC
is the greater of V
IN1
, V
OUT
or V
BAT
Note 3: IN1 and IN2
should be tied together with a low impedance to
ensure that the difference between the two pins does not exceed 100mV
Note 4: All voltage values are with respect to GND.
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 impair device reliability.
Note 6: The LTC4055EUF is guaranteed to meet performance
specifications from 0
C to 70
C. Specifications over the 40
C to 85
C
operating temperature range are assured by design, characterization and
correlation with statistical process controls.
Note 7: Guaranteed by long term current density limitations.
Note 8: Accuracy of programmed current may degrade for currents
greater than 1A.
The
q
indicates specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25
C. V
IN1
= V
IN2
= 5V, V
BAT
= 3.5V, HPWR = 5V, WALL = 0V,
R
PROG
= R
CLPROG
= 100k, unless otherwise noted.
ELECTRICAL CHARACTERISTICS
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
NTC
I
VNTC
V
NTC
Pin Current
V
VNTC
= 2.5V
q
1.5
2.5
3.5
mA
V
VNTC
V
NTC
Bias Voltage
I
VNTC
= 500
A
q
3.4
3.8
V
V
COLD
Cold Temperature Fault Threshold
Rising Threshold
0.74 V
VNTC
V
Voltage
Falling Threshold
0.72 V
VNTC
V
V
HOT
Hot Temperature Fault Threshold
Falling Threshold
0.29 V
VNTC
V
Voltage
Rising Threshold
0.30 V
VNTC
V
V
DIS
NTC Disable Voltage
NTC Input Voltage to GND (Falling)
q
75
100
125
mV
Hysteresis
50
mV
TYPICAL PERFOR A CE CHARACTERISTICS
U
W
Input Supply Current
vs Temperature
TEMPERATURE (
C)
50
25
25
75
0
I
IN
(
A)
100
300
400
500
50
900
4055 G01
200
0
100
600
700
800
V
IN
= 5V
V
BAT
= 4.2V
R
PROG
= R
CLPROG
= 100k
TEMPERATURE (
C)
50
0
I
IN
(
A)
10
20
30
40
60
25
0
25
50
4055 G02
75
100
50
V
IN
= 5V
V
BAT
= 4.2V
R
PROG
= R
CLPROG
= 100k
SUSP = 5V
TEMPERATURE (
C)
50
70
60
50
40
30
20
10
0
25
75
4055 G03
25
0
50
100
I
BAT
(
A)
V
IN
= 0V
V
BAT
= 4.2V
Input Supply Current
vs Temperature (Suspend Mode)
Battery Drain Current vs
Temperature (BAT Powers OUT,
No Load)
5
LTC4055
4055p
TYPICAL PERFOR A CE CHARACTERISTICS
U
W
Input Current Limit vs
Temperature, HPWR = 5V
TEMPERATURE (
C)
50
25
465
I
IN
(mA)
485
515
0
50
75
4055 G04
475
505
495
25
100
125
V
IN
= 5V
V
BAT
= 3.5V
R
PROG
= R
CLPROG
= 100k
R
ON
vs Temperature
Input Current Limit vs
Temperature, HPWR = 0V
TEMPERATURE (
C)
50
I
IN
(mA)
100.0
102.5
105.0
25
75
4055 G05
97.5
95.0
25
0
50
100
125
92.5
90.0
V
IN
= 5V
V
BAT
= 3.5V
R
PROG
= R
CLPROG
= 100k
TEMPERATURE (
C)
50
R
ON
(m
)
200
225
250
25
75
4055 G06
175
150
25
0
50
100
125
125
100
I
LOAD
= 400mA
V
IN
= 4.5V
V
IN
= 5.5V
V
IN
= 5V
PROG Pin Voltage vs Temperature
Battery Regulated Output (Float)
Voltage vs Temperature
CLPROG Pin Voltage
vs Temperature
TEMPERATURE (
C)
50
V
PROG
(V)
0.995
1.000
1.005
25
75
4055 G07
0.990
0.985
0.980
25
0
50
1.010
1.015
1.020
100
V
IN
= 5V
R
PROG
= 100k
TEMPERATURE (
C)
50
V
CLPROG
(V)
0.995
1.000
1.005
25
75
4055 G08
0.990
0.985
0.980
25
0
50
1.010
1.015
1.020
100
V
IN
= 5V
R
CLPROG
= 100k
TEMPERATURE (
C)
50
V
FLOAT
(V)
4.195
4.200
4.205
25
75
4055 G09
4.190
4.185
4.180
25
0
50
4.210
4.215
4.220
100
V
IN
= 5V
Regulated Output Voltage-
Recharge Threshold Voltage
vs Temperature
TEMPERATURE (
C)
50
V
FLOAT
-V
RECHARGE
(V)
95
100
105
25
75
4055 G10
90
85
80
25
0
50
110
115
120
100
V
IN
= 5V
Battery Regulated Output (Float)
Voltage vs Supply Voltage
V
IN
(V)
4.5
V
FLOAT
(V)
4.195
4.200
4.205
5.25
5.75
4055 G11
4.190
4.185
4.180
4.75
5
5.5
4.210
4.215
4.220
6
Battery Current and Voltage
vs Time
TIME (MINUTES)
0
I
BAT
(mA)
V
BAT
AND V
CHRG
(V)
200
400
600
100
300
500
0
2
4
6
1
3
5
40
80
120
160
4055 G12
200
20
0
60
100
140
180
CHRG
V
BAT
I
BAT
0.8AHr CELL
V
IN
= 5V
T
A
= 25
C
R
PROG
= 105k
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