4050f.pm65
1
LTC4050
4050f
Lithium-Ion Linear Battery
Charger with Thermistor Interface
The LTC
4050-4.1/LTC4050-4.2 are complete standalone
constant-current/constant-voltage linear charge control-
lers for lithium-ion (Li-Ion) batteries. Charge current is
programmable and final float voltage has
1% accuracy.
When the input supply is removed, the LTC4050 automati-
cally enters a low quiescent current sleep mode, dropping
the battery drain current to 5
A. An internal comparator
detects the near-end-of-charge (C/10) condition while a
programmable timer, using an external capacitor, sets the
total charge time. Fully discharged cells are automatically
trickle charged at 10% of the programmed current until
cell voltage exceeds 2.49V. The thermistor interface
suspends charging if the cell temperature is outside of a
0
C to 50
C temperature window.
The LTC4050 begins a new charge cycle when a discharged
battery is connected to the charger or when the input power
is applied. In addition, a new charge cycle is automatically
started if the battery remains connected to the charger and
the cell voltage drops below 3.88V for 4.1V cells or below
3.98V for 4.2V cells.
The LTC4050 is available in the 10-pin MSOP package.
s
Complete Standalone Linear Charger Controller
for 1-Cell Lithium-Ion Batteries
s
Thermistor Interface for Battery Temperature
Sensing
s
Preset Charge Voltage with
1% Accuracy
s
Programmable Charge Current
s
C/10 Charge Current Detection Output
s
Programmable Charge Termination Timer
s
Input Supply (Wall Adapter) Detection Output
s
4.5V to 10V Input Voltage Range
s
Automatic Sleep Mode When Input Supply
is Removed (Only 5
A Battery Drain)
s
Automatic Trickle Charging of Low Voltage Cells
s
Automatic Battery Recharge
s
Battery Insertion Detection
s
Space Saving 10-Pin MSOP Package
s
Cellular Phones
s
Handheld Computers
s
Charging Docks and Cradles
APPLICATIO S
U
TYPICAL APPLICATIO
U
Single Cell 4.2V 500mA Li-Ion Battery Charger
FEATURES
DESCRIPTIO
U
V
CC
V
IN
6V
SENSE
DRV
1k
1k
0.2
19.6k
4.2V
Li-Ion
CELL
LTC4050-4.2
*SHUTDOWN INVOKED BY FLOATING THE PROG PIN
BAT
CHRG
9
MBRM120T3
10
F
4050 TA01
1
F
I
BAT
= 500mA
0.1
F
Si9430DY
7
1
6
*
8
5
2
+
3
10
4
ACPR
TIMER
PROG
NTC
GND
10k NTC
DALE NTHS-1206N02
T
, LTC and LT are registered trademarks of Linear Technology Corporation.
Charge Current vs
Thermistor Temperature
THERMISTOR TEMPERATURE (
C)
50
CHARGE CURRENT (mA)
400
500
600
25
75
4050 TA05
300
200
25
0
50
100
125
100
0
V
BAT
= 3.7V
2
LTC4050
4050f
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
CC
Input Supply Voltage
q
4.5
10
V
I
CC
Input Supply Current
Charger On, Current Mode
q
1.3
3
mA
Shutdown Mode
q
1.3
3
mA
Sleep Mode (Battery Drain Current)
5
15
A
V
BAT
Regulated Output (Float) Voltage in
LTC4050-4.1; 5V
V
CC
10V, 0
C
T
A
85
C
4.059
4.1
4.141
V
Constant Voltage Mode
LTC4050-4.2; 5V
V
CC
10V, 0
C
T
A
85
C
4.158
4.2
4.242
V
LTC4050-4.1; 5V
V
CC
10V
q
4.039
4.1
4.141
V
LTC4050-4.2; 5V
V
CC
10V
q
4.137
4.2
4.242
V
I
BAT
Current Mode Charge Current
R
PROG
= 19.6k, R
SENSE
= 0.2
440
500
535
mA
R
PROG
= 19.6k, R
SENSE
= 0.2
q
415
585
mA
R
PROG
= 97.6k, R
SENSE
= 0.2
60
100
140
mA
I
TRIKL
Trickle Charge Current
V
BAT
= 2V, R
PROG
= 19.6k, I
TRIKL
= (V
CC
V
SENSE
)/0.2
q
20
55
90
mA
V
TRIKL
Trickle Charge Threshold Voltage
q
2.41
2.49
2.58
V
V
UV
V
CC
Undervoltage Lockout Voltage
q
4
4.5
V
V
UV
V
CC
Undervoltage Lockout Hysteresis
130
mV
V
MSD
PROG Pin Manual Shutdown
3.6
V
Threshold Voltage
V
ASD
Automatic Shutdown Threshold Voltage
(V
CC
V
BAT
) High to Low
25
54
85
mV
(V
CC
V
BAT
) Low to High
40
69
100
mV
I
PROG
PROG Pin Current
Internal Pull-Up Current, No R
PROG
2.3
A
PROG Pin Source Current,
V
PROG
5mV
q
300
A
V
PROG
PROG Pin Voltage
R
PROG
=19.6k
2.47
V
V
ACPR
ACPR Pin Output Low Voltage
I
ACPR
= 5mA
0.525
V
I
CHRG
CHRG Pin Weak Pull-Down Current
V
CHRG
= 1V
32
A
V
CHRG
CHRG Pin Output Low Voltage
I
CHRG
= 5mA
0.525
V
R
HOT
Thermistor Resistance for Hot Fault
3.7
4.1
4.4
k
R
COLD
Thermistor Resistance for Cold Fault
25
28.5
31
k
ORDER PART
NUMBER
(Note 1)
Input Supply Voltage (V
CC
) ...................................... 12V
SENSE, DRV, BAT, SEL,
TIMER, PROG, CHRG, ACPR ................. 0.3V to 12V
Operating Temperature Range (Note 2) . 40
C to 85
C
Storage Temperature Range ................. 65
C to 150
C
Lead Temperature (Soldering, 10 sec).................. 300
C
LTC4050EMS-4.1
LTC4050EMS-4.2
T
JMAX
= 140
C,
JA
= 180
C/W
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ABSOLUTE
M
AXI
M
U
M
RATINGS
W
W
W
U
PACKAGE/ORDER I
N
FOR
M
ATIO
N
W
U
U
MS PART MARKING
LTTW
LTTX
The
q
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25
C. V
CC
= 6V unless otherwise noted.
ELECTRICAL CHARACTERISTICS
1
2
3
4
5
BAT
NTC
CHRG
TIMER
GND
10
9
8
7
6
ACPR
SENSE
V
CC
DRV
PROG
TOP VIEW
MS PACKAGE
10-LEAD PLASTIC MSOP
3
LTC4050
TYPICAL PERFOR A CE CHARACTERISTICS
U
W
TEMPERATURE (
C)
50
460
I
BA
T
(mA)
480
500
520
540
25
0
25
50
LTC4050 G01
75
100
125
R
PROG
= 19.6k
R
SEN
= 0.2
V
BAT
= 3V
V
CC
= 6V
V
CC
(V)
4
I
BA
T
(mA) 500
505
510
LC4050 G02
495
490
480
6
8
10
485
520
515
R
PROG
= 19.6k
R
SEN
= 0.2
V
BAT
= 3V
T
A
= 25
C
TEMPERATURE (
C)
50
I
TRKL
(mA)
60
65
70
25
75
LTC4050 G03
55
50
25
0
50
100
125
45
40
R
PROG
= 19.6k
R
SEN
= 0.2
V
BAT
= 2V
V
CC
= 6V
V
CC
(V)
4
40
I
TRKL
(mA)
45
50
55
60
65
70
6
8
10
LTC4050 G04
R
PROG
= 19.6k
R
SEN
= 0.2
V
BAT
= 2V
T
A
= 25
C
TEMPERATURE (
C)
50
25
2.46
V
TRKL
(V)
2.48
2.51
0
50
75
LTC4050 G05
2.47
2.50
2.49
25
100
125
V
CC
= 6V
R
PROG
= 19.6k
V
CC
(V)
4
2.45
V
TRKL
(V)
2.47
2.48
2.49
2.50
2.51
2.52
6
8
LTC4050 G06
2.53
2.54
2.55
2.46
10
R
PROG
= 19.6k
T
A
= 25
C
Charge Current vs Temperature
Charge Current vs V
CC
Trickle Charge Current
vs Temperature
Trickle Charge Current vs V
CC
Trickle Charge Threshold Voltage
vs Temperature
Trickle Charge Threshold Voltage
vs V
CC
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
I
C/10
10% Charge Current Indication Level
R
PROG
= 19.6k, R
SENSE
= 0.2
q
25
50
100
mA
t
TIMER
TIMER Accuracy
C
TIMER
= 0.1
F
10
%
V
RECHRG
Recharge Threshold Voltage
V
BAT
from High to Low (LTC4050-4.1)
3.83
3.88
V
V
BAT
from High to Low (LTC4050-4.2)
3.93
3.98
V
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2: The LTC4050E 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.
The
q
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25
C. V
CC
= 6V unless otherwise noted.
ELECTRICAL CHARACTERISTICS
4
LTC4050
TYPICAL PERFOR A CE CHARACTERISTICS
U
W
TEMPERATURE (
C)
50
28.1
R
COLD
(k
)
28.2
28.4
28.5
28.6
50
29.0
LTC4050 G13
28.3
0
25
75
100
25
125
28.7
28.8
28.9
V
CC
= 6V
V
CC
(V)
4
R
HOT
(k
)
4.100
4.125
10
LT4050 G14
4.075
4.050
6
8
4.150
T
A
= 25
C
V
CC
(V)
4
R
COLD
(k
)
28.50
28.55
10
LTC4050 G15
28.45
28.40
6
8
28.60
T
A
= 25
C
TEMPERATURE (
C)
50
90
TIMER (%)
95
100
105
110
25
0
25
50
LTC4050 G10
75
100
125
V
CC
= 6V
V
BAT
= 3V
C
TIMER
= 0.1
F
V
CC
(V)
4
90
TIMER (%)
95
100
105
110
5
6
7
8
LTC4050 G11
9
10
V
BAT
= 3V
C
TIMER
= 0.1
F
T
A
= 25
C
TEMPERATURE (
C)
50
R
HOT
(k
)
4.12
4.14
4.16
25
75
LTC4050 G12
4.10
4.08
25
0
50
100
125
4.06
4.04
V
CC
= 6V
Timer Accuracy vs Temperature
Timer Accuracy vs V
CC
NTC R
HOT
Threshold Voltage
vs Temperature
NTC R
COLD
Threshold Voltage
vs Temperature
NTC R
HOT
Threshold Voltage
vs V
CC
NTC R
COLD
Threshold Voltage
vs V
CC
TEMPERATURE (
C)
50
3.7
V
RECHRG
(V)
3.8
3.9
4.0
4.1
25
0
25
50
LTC4050 G07
75
100
125
LTC4050-4.1
LTC4050-4.2
V
CC
= 6V
TEMPERATURE (
C)
50
V
PROG
(V)
2.470
2.475
2.480
25
75
LTC4050 G08
2.465
2.460
25
0
50
100
125
2.455
2.450
V
CC
= 6V
R
PROG
= 19.6k
V
CC
(V)
4
V
PROG
(V)
2.47
2.48
LTC4050 G09
2.46
2.45
6
8
10
2.50
2.49
R
PROG
= 19.6k
T
A
= 25
C
Recharge Threshold Voltage
vs Temperature
PROG Pin Voltage vs Temperature
PROG Pin Voltage vs V
CC
5
LTC4050
4050f
PI
N
FU
N
CTIO
N
S
U
U
U
BAT (Pin 1): Battery Sense Input. A precision internal
resistor divider on this pin sets the final float voltage. The
resistor divider is disconnected in sleep mode to reduce
the current drain on the battery. A bypass capacitor of
10
F or more is required to keep the loop stable when the
battery is not connected.
NTC (Pin 2): Thermistor Interface Input. A 10k
Dale
Curve 2 NTC thermistor (or other 10k
NTC thermistor
with a room temperature beta of around 3400) is con-
nected from this pin to ground. The charge cycle will be
disabled and the timer will be placed on hold if the
thermistor temperature is above 50
C or below 0
C.
CHRG (Pin 3): Charge Status Open-Drain Output. When
the battery is charging, the CHRG pin is pulled low by an
internal N-channel MOSFET. When the charge current
drops to 10% of the full-scale current for more than 15ms,
the N-channel MOSFET turns off and a 32
A current
source is connected from the CHRG pin to GND. When the
timer runs out or the input supply is removed, the current
source is disconnected and the CHRG pin becomes high
impedance.
TIMER (Pin 4): Timer Capacitor and Constant-Voltage
Mode Disable Input Pin. The timer period is set by placing
a capacitor, C
TIMER
, to GND. The timer period is t
TIMER
=
(C
TIMER
3 hours)/(0.1
F). Shorting the TIMER pin to
GND will disable the internal timer function and the C/10
function.
GND (Pin 5): Ground.
PROG (Pin 6): Charge Current Program and Shutdown
Input Pin. The charge current is programmed by connect-
ing a resistor, R
PROG
to ground. The charge current is I
BAT
= (V
PROG
800
)/(R
PROG
R
SENSE
). The IC can be forced
into shutdown by floating the PROG pin and allowing the
internal 2.3
A current source to pull the pin above the 3.6V
shutdown threshold voltage.
DRV (Pin 7): Drive Output Pin for the P-Channel MOSFET
or PNP Transistor. The impedance is high at this pin,
therefore, if a PNP pass transistor is used, it must have
high gain.
V
CC
(Pin 8): Positive Input Supply Voltage. V
CC
can range
from 4.5V to 10V. Bypass this pin with a 1
F capacitor.
When V
BAT
is within 54mV of V
CC
, the LTC4050 is forced
into sleep mode, dropping I
CC
to 5
A.
SENSE (Pin 9): Current Sense Input. A sense resistor,
R
SENSE
, must be connected from V
CC
to the SENSE pin.
Select a resistor value that will develop approximately
100mV at the programmed full-scale charge current.
This resistor is chosen using the following equation:
R
SENSE
= (V
PROG
800
)/(R
PROG
I
BAT
)
ACPR (Pin 10): Wall Adapter Present Output. When the
input voltage (wall adaptor) is applied to the LTC4050, this
pin is pulled to ground by an internal N-channel MOSFET
that is capable of sinking 5mA suitable for driving an
external LED.
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