LTC4056-4.2
Linear Li-Ion Charger
with Termination in ThinSOT
FEATURES
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DESCRIPTIO
Standalone Li-Ion Charger with Termination
Programmable Termination Timer
No Sense Resistor or Blocking Diode Required
Suitable for USB-Powered Charging
Undervoltage Charge Current Limiting
Preset Charge Voltage with
±0.6%
Accuracy
Programmable Charge Current: 200mA to 700mA
Automatic Recharge with Shortened Charge Cycle
Self-Protection for Overcurrent/Overtemperature
40µA Supply Current in Shutdown Mode
Negligible Battery Drain Current in Shutdown
Low Battery Charge Conditioning (Trickle Charging)
CHRG Status Output including AC Present
PCB Total Solution Area only 75mm
2
(700mA)
Low Profile (1mm) SOT-23 Package
The LTC
®
4056 is a low cost, single-cell, constant-current/
constant-voltage Li-Ion battery charger controller with a
programmable termination timer. When combined with a
few external components, the LTC4056 forms a very small
standalone charger for single cell lithium-ion batteries.
Charge current and charge time are set externally with a
single resistor and capacitor, respectively. The LTC4056
charges to a final float voltage accurate to
±0.6%.
Manual
shutdown is accomplished by grounding the TIMER/
SHDN pin, while removing input power automatically puts
the LTC4056 into a sleep mode. Both the shutdown and
sleep modes drain near zero current from the battery; the
shutdown mode reduces supply current to 40µA.
The output driver is both current limited and thermally
protected to prevent operating outside of safe limits. No
external blocking diode or sense resistor is required. The
LTC4056 also includes low battery charge conditioning
(trickle charging), undervoltage charge current limiting,
automatic recharge and a charge status output.
The LTC4056 is available in a low profile (1mm) 8-lead
SOT-23 (ThinSOT
TM
) package.
, LTC and LT are registered trademarks of Linear Technology Corporation.
ThinSOT is a trademark of Linear Technology Corporation.
APPLICATIO S
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Cellular Telephones
Handheld Computers
Digital Cameras
Charging Docks and Cradles
Low Cost and Small Size Chargers
TYPICAL APPLICATIO
V
IN
Undervoltage Charge
Current Limiting
800
V
BAT
= 4V
R
PROG
= 1.3k
700
I
CHG
= 700mA
INPUT Z = 100mΩ
600
700mA
ZXT1M322
IBAT (mA)
V
IN
4.5V TO 6.5V
CHARGE
STATUS
1µF
1µF
1.3k
V
CC
LTC4056
I
SENSE
DRIVE
BAT
500
400
300
200
100
CHRG
TIMER/SHDN
PROG
GND
UNDERVOLTAGE CHARGE
CURRENT LIMITING
+
1-CELL
4.2V Li-Ion
4056-4.2 TA01
0
4.40 4.45
U
CONSTANT
CURRENT
UNDERVOLTAGE
LOCKOUT
AT 4.35V
4.50 4.55 4.60 4.65 4.70 4.75
V
IN
(V)
4056 TA02
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405642f
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LTC4056-4.2
ABSOLUTE
(Note 1)
AXI U RATI GS
PACKAGE/ORDER I FOR ATIO
TOP VIEW
V
CC
1
I
SENSE
2
DRIVE 3
GND 4
8 CHRG
TIMER/
7
SHDN
6 BAT
5 PROG
Input Supply Voltage (V
CC
) ........................– 0.3V to 10V
BAT, CHRG ................................................– 0.3V to 10V
DRIVE, PROG, TIMER/SHDN ....... – 0.3V to (V
CC
+ 0.3V)
Output Current (I
SENSE
) ...................................... 900mA
Short-Circuit Duration (BAT, I
SENSE
) ............Continuous
Junction Temperature ........................................... 125°C
Operating Ambient Temperature Range
(Note 2) .............................................. – 40°C to 85°C
Storage Temperature Range ................. – 65°C to 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C
ORDER PART
NUMBER
LTC4056ETS8-4.2
TS8 PART
MARKING
LTG5
TS8 PACKAGE
8-LEAD PLASTIC SOT-23
T
JMAX
= 125°C,
θ
JA
= 120°C/W TO 200°C/W
DEPENDING ON PC BOARD LAYOUT
Consult LTC Marketing for parts specified with wider operating temperature ranges.
The
q
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
CC
= 5V.
SYMBOL
V
CC
Supply
V
CC
I
CC
I
SHDN
I
BMS
I
BSL
V
UVLOI
V
UVLOD
V
UVHYS
V
UVCL
Input Supply Voltage (Note 3)
Quiescent V
CC
Supply Current
V
CC
Supply Current in Manual Shutdown
Battery Drain Current in
Manual Shutdown (Note 4)
Battery Drain Current in
Sleep Mode (Note 5)
Undervoltage Rising Threshold
Undervoltage Falling Threshold
Undervoltage Hysteresis
Undervoltage Charge Current Limit Threshold
q
q
ELECTRICAL CHARACTERISTICS
PARAMETER
CONDITIONS
MIN
4.5
TYP
MAX
6.5
UNITS
V
µA
µA
µA
µA
V
V
mV
V
V
BAT
= 4.5V (Forces I
DRIVE
= 0)
I
PROG
= 200µA (R
PROG
= 5k)
V
TIMER/SHDN
= 0V
V
TIMER/SHDN
= 0V
V
CC
= 0V
V
CC
Increasing
V
CC
Decreasing
V
UVLOI
-V
UVLOD
q
400
40
–1
–1
4.325
4.275
0
0
4.40
4.35
50
4.575
90
4.175
4.158
137
590
170
4.200
4.200
183
640
600
60
1
1
4.475
4.425
q
q
q
q
V
UVCL
-V
UVLOI
UV Charge Current to UVLO Threshold Margin
Charging Performance
V
FLOAT
I
BAT
Output Float Voltage in
Constant Voltage Mode
Output Full-Scale Current in
Constant Current Mode
I
BAT
= 10mA
I
BAT
= 10mA, 4.75V
≤
V
CC
≤
6.5V
R
PROG
= 5k, 4.75V
≤
V
CC
≤
6.5V,
PNP Beta > 50, 0°C
≤
T
A
≤
85°C
R
PROG
= 1.43k, 4.75V
≤
V
CC
≤
6.5V,
PNP Beta > 50, 0°C
≤
T
A
≤
85°C
I
DSINK
I
TRIKL
V
TRIKL
∆V
TRIKL
V
PROG1
V
PROG2
Drive Output Current
Trickle Charge Current
Trickle Charge Threshold Voltage
Trickle Charge Hysteresis Voltage
PROG Pin Voltage
PROG Pin Voltage
R
PROG
= 5k (I
PROG
= 200µA)
R
PROG
= 1.43k (I
PROG
= 700µA)
V
DRIVE
= 3V
V
BAT
= 2V, R
PROG
= 5k
V
BAT
= 2V, R
PROG
= 1.43k
V
BAT
Falling
250
4.225
4.242
228
690
q
q
30
5
12
7
20
2.80
70
1
1
10
28
2.87
95
1.02
1.02
q
2.73
45
0.98
0.98
q
q
405642f
2
U
mV
V
V
mA
mA
mA
mA
mA
V
mV
V
V
W
U
U
W W
W
LTC4056-4.2
The
q
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
CC
= 5V.
SYMBOL
∆V
RECHRG
T
TIMER
V
MSDT
V
MSHYS
I
SHDN
Protection
I
DSHRT
I
PSHRT
Status Output
I
CHRG
V
CHRG
CHRG Pin Weak Pull-Down Current
CHRG Output Low Voltage
V
CHRG
= 1V, V
TIMER/SHDN
= 0V
I
CHRG
= 10mA
q
ELECTRICAL CHARACTERISTICS
PARAMETER
Recharge Threshold Voltage
TIMER/SHDN Accuracy
Manual Shutdown Threshold Voltage
Manual Shutdown Hysteresis Voltage
TIMER/SHDN Pin Pull-up Current
Drive Output Short-Circuit Current Limit
PROG Pin Short-Circuit Current Limit
CONDITIONS
V
FLOAT
– V
RECHRG
, V
BAT
> V
TRIKL
,
Charge Termination Timer Expired
C
TIMER
= 1µF R
PROG
= 1.43k
V
TIMER/SHDN
Increasing
V
TIMER/SHDN
Decreasing
V
TIMER/SHDN
= 0V
V
DRIVE
= V
CC
V
PROG
= 0V
q
q
MIN
100
TYP
150
10
MAX
200
12
1
125
–4
130
UNITS
mV
%
V
mV
µA
mA
mA
Charger Manual Control
q
0.6
50
– 10
30
0.82
75
–7
65
1.4
6
12
0.2
18
0.4
µA
V
Note 1:
Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2:
The LTC4056E is guaranteed to meet performance specifications
from 0°C to 70°C ambient temperature range. Specifications over the
– 40°C to 85°C operating ambient temperature range are assured by
design, characterization and correlation with statistical process controls.
Note 3:
Although the LTC4056 will operate with input voltages as low as
4.5V, charging will not begin until V
CC
exceeds V
UVCL
.
Note 4:
Assumes that the external PNP pass transistor has negligible B-C
reverse-leakage current when the collector is biased at 4.2V (V
BAT
) and the
base is biased at 5V (V
CC
).
Note 5:
Assumes that the external PNP pass transistor has negligible B-E
reverse-leakage current when the emitter is biased at 0V (V
CC
) and the
base is biased at 4.2V (V
BAT
).
TYPICAL PERFOR A CE CHARACTERISTICS
Float Voltage vs Temperature and
Supply Voltage
4.215
4.210
4.205
FLOAT VOLTAGE (V)
I
BAT
= 10mA
PNP = FZT749
V
FLOAT
(V)
4.200
4.195
4.190
4.185
–50 –25
V
CC
= 4.75V
V
CC
= 6.5V
4.200
I
BAT
(mA)
50
25
75
0
TEMPERATURE (°C)
U W
100
Float Voltage vs I
BAT
4.202
V
CC
= 5V
T
A
= 25°C
PNP = FZT749
4.201 R
PROG
= 1.30k
220
I
BAT
vs Temperature and
Supply Voltage
R
PROG
= 4.53k
PNP = FZT749
215
210
205
200
195
V
CC
= 6.5V
V
CC
= 4.75V
4.199
190
185
4.198
125
0
100
200
300 400
I
BAT
(mA)
500
600
700
180
– 50 – 25
0
75
50
25
TEMPERATURE (°C)
100
125
4056-4.2 G01
4056-4.2 G02
4056-4.2 G03
405642f
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LTC4056-4.2
TYPICAL PERFOR A CE CHARACTERISTICS
I
BAT
vs Temperature and
Supply Voltage
730
720
V
CC
= 6.5V
710
I
BAT
(mA)
R
PROG
= 1.30k
PNP = FZT749
I
BAT
(mA)
V
CC
= 4.75V
700
690
680
670
–50
500
400
300
200
100
BAT PIN MUST BE
DISCONNECTED
AND SET BETWEEN
2.9V AND 4.2V TO
FORCE CC MODE
IN THIS AREA
TIMER ERROR (%)
–25
0
25
50
TEMPERATURE (°C)
TIMER/SHDN Pin Pull-Up Current
vs Temperature and Supply Voltage
12
10
8
I
SHDN
(µA)
V
TIMER/SHDN
= 0V
V
CC
= 6.5V
6
4
2
0
–50 –25
V
CC
= 4.75V
I
CHRG
(µA)
CHRG Pin Output Low Voltage
vs Temperature
0.40
V
BAT
= 0V
I
CHRG
= 10mA
V
CC
= 5V
1.0050
0.35
V
CHRG
(V)
0.30
V
PROG
(V)
0.25
0.20
–50
–25
4
U W
75
4056-4.2 G04
I
BAT
vs V
BAT
V
CC
= 5V
700 T
A
= 25°C
PNP = FZT749
600
R
PROG
1.30k
800
5
4
3
2
1
0
–1
–2
–3
–4
0
1
2
3
V
BAT
(V)
4
5
4056-4.2 G05
Timer Error vs Temperature
V
CC
= 5V
R
PROG
= 1.43k
R
PROG
4.53k
100
0
–5
–50 –25
50
25
0
75
TEMPERATURE (°C)
100
125
4056-4.2 G06
CHRG Pin Weak Pull-Down Current
vs Temperature and V
CHRG
20
V
TIMER/SHDN
= 0V
V
CC
= 5V
15
V
CHRG
= 6.5V
10
V
CHRG
= 1V
50
25
75
0
TEMPERATURE (°C)
100
125
5
–50
–25
0
25
50
75
TEMPERATURE (°C)
100
125
4056-4.2 G07
4056-4.2 G08
PROG Pin Voltage
vs Temperature and R
PROG
V
CC
= 5V
1.0025
R
PROG
= 4.53k
1.0000
R
PROG
= 1.30k
0.9975
0
25
50
TEMPERATURE (°C)
75
100
0.9950
–50
–25
75
0
25
50
TEMPERATURE (°C)
100
125
4056-4.2 G09
4056-4.2 G10
405642f
LTC4056-4.2
PI FU CTIO S
V
CC
(Pin 1):
Positive Input Supply Voltage. This pin
supplies power to the internal control circuitry and exter-
nal PNP transistor through the internal current sense
resistor. This pin should be bypassed to ground with a
capacitor in the range of 1µF to 10µF.
I
SENSE
(Pin 2):
Sense Node for Charge Current. Current
from V
CC
passes through the internal current sense resis-
tor and out of the I
SENSE
pin to supply current to the emitter
of the external PNP transistor. The collector of the PNP
provides charge current to the battery.
DRIVE (Pin 3):
Base Drive Output for the External PNP
Pass Transistor. Provides a controlled sink current to
drive the base of the PNP. This pin has current limiting
protection.
GND (Pin 4):
Ground. Provides a reference for the internal
voltage regulator and a return for all internal circuits.
When in the constant voltage mode, the LTC4056 will
precisely regulate the voltage between the BAT and GND
pins. The battery ground should connect close to the GND
pin to avoid voltage drop errors.
PROG (Pin 5):
Charge Current Programming Pin. Pro-
vides a virtual reference voltage of 1V for an external
resistor (R
PROG
) connected between this pin and ground
to program the battery charge current. In constant current
mode the typical charge current is 915 times the current
through this resistor (I
CHG
= 915V/R
PROG
). Current is
limited to approximately 1.4mA (I
CHG
of approximately
1.4A).
BAT (Pin 6):
Battery Voltage Sense Input. A precision
internal resistor divider sets the final float voltage on this
pin. This divider is disconnected in the manual shutdown
or sleep mode. No bypass capacitance is needed on this
pin for stable operation when a battery is present. How-
ever, any low ESR capacitor exceeding 22µF on this pin
should be decoupled with 0.2Ω to 1Ω resistor. Without a
battery, a minimum bypass capacitance of 4.7µF with
0.5Ω series resistance is required.
TIMER/SHDN (Pin 7):
Programmable Charge Termination
Timer and Shutdown Input. Pulling this pin below the
shutdown threshold voltage will shut down the charger
reducing the supply current to approximately 40µA and
the battery drain current to near 0µA. A capacitor on this
pin programs the charge termination timer.
CHRG (Pin 8):
Open-Drain Charge Status Output. When
the battery is being charged, the CHRG pin is pulled low by
an internal N-channel MOSFET. When the timer has timed
out (terminating the charge cycle) or when the LTC4056 is
in shutdown, but power is applied to the IC (i.e., V
CC
>
V
UVLOI
), a 12µA current source is connected from the
CHRG pin to ground. The CHRG pin is forced to a high
impedance state when input power is not present (i.e., V
CC
< V
UVLOD
).
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