LTC4078X
Dual Input Li-Ion Battery
Charger with Overvoltage Protection
FEATURES
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DESCRIPTION
The LTC
®
4078X is a standalone linear charger that is
capable of charging a single-cell Li-Ion/Polymer battery
from both wall adapter and USB inputs. The charger can
detect power at the inputs and automatically select the
appropriate power source for charging.
No external sense resistor or blocking diode is required
for charging due to the internal MOSFET architecture.
The LTC4078X features a maximum 22V rating for both
wall adapter and USB inputs, although charging stops if
the selected power source exceeds the overvoltage limit.
Internal thermal feedback regulates the battery charge
current to maintain a constant die temperature during high
power operation or high ambient temperature conditions.
The float voltage is fixed at 4.2V and the charge current
is programmed with an external resistor. The LTC4078X
terminates the charge cycle when the charge current drops
below the programmed termination threshold after the
final float voltage is reached.
Other features include battery present detection, automatic
recharge, undervoltage lockout, charge status outputs, and
“power present” status outputs to indicate the presence of
wall adapter or USB power. The device is offered in a low
profile (0.75mm) 3mm
×
3mm 10-lead DFN package.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All
other trademarks are the property of their respective owners.
*Protected by U.S. Patents including
6522118, 6700364.
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■
■
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22V Maximum Voltage for Wall Adapter and
USB Inputs
Charge Single-Cell Li-Ion Batteries from Wall
Adapter and USB Inputs
Automatic Input Power Detection and Selection
Charge Current Programmable Up to 950mA from
Wall Adapter Input
Overvoltage Lockout for Wall Adapter and USB Inputs
Battery Detection Input Disables Charger When No
Battery is Present
No External MOSFET, Sense Resistor or Blocking
Diode Needed
Thermal Regulation Maximizes Charge Rate Without
Risk of Overheating*
Preset Charge Voltage with ±0.6% Accuracy
Programmable Charge Current Termination
40µA USB Suspend Current in Shutdown
Charge Status Output
Automatic Recharge
No Trickle Charge
Available in a Thermally Enhanced, Low Profile
(0.75mm) 10-Lead (3mm
×
3mm) DFN Package
APPLICATIONS
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■
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Cellular Telephones
Handheld Computers
Portable MP3 Players
Digital Cameras
TYPICAL APPLICATION
High Voltage Dual Input Battery Charger
for Li-Ion Battery Pack
WALL
ADAPTER
USB
PORT
1µF
1µF
LTC4078X
DCIN
USBIN
IUSB
ITERM
GND
2k
1%
4078X TA01
Charger Current vs Supply Voltage
900
800
700
600
I
BAT
(mA)
500
400
300
200
100
0
2
3
4
5
6
7
8
SUPPLY VOLTAGE (V)
19
20
CHARGE
FROM USBIN
R
IDC
= 1.24k
R
IUSB
= 2k
V
BAT
= 3.5V
V
BATDET
= 0V
CHARGE FROM DCIN
800mA (WALL)
500mA (USB)
BAT
BATDET
3.9k
+
2k
IDC
1% 1.24k
1%
4.2V
Li-Ion
BATTERY
PACK
4078x TA01b
4078xf
1
LTC4078X
ABSOLUTE MAXIMUM RATINGS
(Note 1)
PIN CONFIGURATION
TOP VIEW
USBIN
IUSB
ITERM
PWR
CHRG
1
2
3
4
5
11
10 DCIN
9 BAT
8 IDC
7 BATDET
6 ENABLE
Input Supply Voltage (DCIN, USBIN) ............–0.3 to 22V
ENABLE,
⎯
C
⎯
H
⎯
R
⎯
G,
⎯
P
⎯
W
⎯
R, BATDET, BAT...............–0.3 to 6V
IDC, IUSB, ITERM Pin Current .................................1mA
DCIN, USBIN, BAT Pin Current ....................................1A
BAT Short-Circuit Duration............................Continuous
Maximum Junction Temperature .......................... 125°C
Operating Temperature Range (Note 2) ... –40°C to 85°C
Storage Temperature Range................... –65°C to 125°C
DD PACKAGE
10-LEAD (3mm
×
3mm) PLASTIC DFN
T
JMAX
= 125°C,
θ
JA
= 40°C/W (Note 3)
EXPOSED PAD (PIN 11) IS GND, MUST BE SOLDERED TO PCB
ORDER INFORMATION
LEAD FREE FINISH
LTC4078XEDD#PBF
TAPE AND REEL
LTC4078XEDD#TRPBF
PART MARKING
LCYP
PACKAGE DESCRIPTION
10-Lead (3mm
×
3mm) Plastic DFN
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/
ELECTRICAL CHARACTERISTICS
SYMBOL
V
DCIN
V
USBIN
I
DCIN
PARAMETER
Operating Supply Voltage
Operating Supply Voltage
DCIN Supply Current
The
●
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
DCIN
= 5V, V
USBIN
= 5V unless otherwise noted.
CONDITIONS
●
●
MIN
4.3
4.3
TYP
MAX
5.5
5.5
UNITS
V
V
µA
µA
µA
µA
µA
µA
µA
µA
µA
V
V
mA
mA
mA
µA
µA
µA
Charge Mode (Note 4), R
IDC
= 10k
Standby Mode; Charge Terminated
Shutdown Mode (ENABLE = 5V)
Overvoltage Mode (V
DCIN
= 10V)
Charge Mode (Note 5), R
IUSB
= 10k, V
DCIN
= 0V
Standby Mode; Charge Terminated, V
DCIN
= 0V
Shutdown (V
DCIN
= 0V, ENABLE = 0V)
Overvoltage Mode (V
USBIN
= 10V)
V
DCIN
> V
USBIN
I
BAT
= 1mA
I
BAT
= 1mA, 0°C < T
A
< 85°C
R
IDC
= 1.25k, Constant-Current Mode
R
IUSB
= 2.1k, Constant-Current Mode
R
IDC
= 10k or R
IUSB
= 10k
Standby Mode, Charge Terminated
Shutdown Mode (Charger Disabled)
Sleep Mode (V
DCIN
= 0V, V
USBIN
= 0V)
●
●
350
70
40
70
350
70
40
70
23
4.185
4.165
4.2
4.2
800
476
100
–7.5
–7.5
–7.5
800
120
80
140
800
120
80
140
40
4.215
4.235
830
495
107
–12
–12
–12
I
USBIN
USBIN Supply Current
●
●
V
FLOAT
I
BAT
Regulated Output (Float) Voltage
BAT Pin Current
●
●
●
770
455
93
4078xf
2
LTC4078X
ELECTRICAL CHARACTERISTICS
SYMBOL
V
IDC
V
IUSB
I
TERMINATE
PARAMETER
IDC Pin Regulated Voltage
IUSB Pin Regulated Voltage
Charge Current Termination Threshold
The
●
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
DCIN
= 5V, V
USBIN
= 5V unless otherwise noted.
CONDITIONS
Constant-Current Mode
Constant-Current Mode
R
ITERM
= 1k
R
ITERM
= 2k
R
ITERM
= 10k
R
ITERM
= 20k
From Low to High
Hysteresis
From Low to High
Hysteresis
From Low to High
Hysteresis
From Low to High
Hysteresis
V
DCIN
from Low to High, V
BAT
= 4.2V
V
DCIN
from High to Low, V
BAT
= 4.2V
V
USBIN
from Low to High
V
USBIN
from High to Low
●
●
●
●
●
MIN
TYP
1
1
MAX
UNITS
V
V
90
42
8
3.5
4
3.8
5.8
5.8
70
10
70
10
0.6
1
1.65
2
4
100
50
10
5
4.15
190
3.95
170
6
185
6
185
120
40
120
40
0.9
2
1.75
4
4.2
0.12
110
58
12
6.5
4.3
4.1
6.2
6.2
170
70
170
70
1.2
3.5
1.85
6
4.4
0.35
160
6.75
2.4
mA
mA
mA
mA
V
mV
V
mV
V
mV
V
mV
mV
mV
mV
mV
V
MΩ
V
µA
V
V
mV
ms
ms
mΩ
mΩ
°C
V
UVDC
V
UVUSB
V
OVDC
V
OVUSB
V
ASD-DC
V
ASD-USB
V
ENABLE
R
ENABLE
V
BDET
I
BATDET
V
BOC
V
OL
ΔV
RECHRG
t
RECHRG
t
TERMINATE
R
ON-DC
R
ON-USB
T
LIM
DCIN Undervoltage Lockout Voltage
USBIN Undervoltage Lockout Voltage
DCIN Overvoltage Lockout Voltage
USBIN Overvoltage Lockout Voltage
V
DCIN
– V
BAT
Lockout Threshold
V
USBIN
– V
BAT
Lockout Threshold
ENABLE Input Threshold Voltage
ENABLE Pulldown Resistance
BATDET Input Threshold Voltage
BATDET Pull-Up Current
BATDET Open Circuit Voltage
Output Low Voltage
(
⎯
C
⎯
H
⎯
R
⎯
G,
⎯
P
⎯
W
⎯
R)
Recharge Battery Threshold Voltage
Recharge Comparator Filter Time
Termination Comparator Filter Time
Power FET “ON” Resistance
(Between DCIN and BAT)
Power FET “ON” Resistance
(Between USBIN and BAT)
Junction Temperature in Constant-
Temperature Mode
From Low to High
V
BATDET
= 0V
V
DCIN
= 5V, V
USBIN
= 5V
I
SINK
= 5mA
V
FLOAT
– V
RECHRG
, 0°C < T
A
< 85°C
V
BAT
from High to Low
I
BAT
Drops Below Termination Threshold
90
2.25
1
125
4.1
1.6
600
700
120
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 LTC4078X is guaranteed to meet the performance
specifications from 0°C to 85°C. Specifications over the –40°C to 85°C
operating temperature range are assured by design, characterization and
correlation with statistical process controls.
Note 3:
Failure to correctly solder the exposed backside of the package to
the PC board will result in a thermal resistance much higher than 40°C/W.
See Thermal Considerations.
Note 4:
Supply current includes IDC and ITERM pin current (approximately
100µA each) but does not include any current delivered to the battery
through the BAT pin.
Note 5:
Supply current includes IUSB and ITERM pin current
(approximately 100µA each) but does not include any current delivered to
the battery through the BAT pin.
4078xf
3
LTC4078X
TYPICAL PERFORMANCE CHARACTERISTICS
Regulated Output (Float) Voltage
vs Charge Current
4.26
4.24
4.22
V
FLOAT
(V)
V
FLOAT
(V)
4.20
4.18
4.16
4.14
4.12
4.10
0
100 200 300 400 500 600 700 800 900
I
BAT
(mA)
4078x G01
T
A
= 25°C, unless otherwise specified.
IDC Pin Voltage vs Temperature
(Constant-Current Mode)
1.008
1.006
1.004
1.002
V
IDC
(V)
1.000
0.998
0.996
0.994
V
DCIN
= 5V
Regulated Output (Float) Voltage
vs Temperature
4.220
4.215
4.210
V
DCIN
= V
USBIN
= 5V
V
DCIN
= V
USBIN
= 5V
R
IDC
= 1.24k
4.205
4.200
4.195
4.190
4.185
4.180
–10
10
30
50
TEMPERATURE (°C)
70
90
4078x G02
R
IDC
= R
IUSB
= 2k
0.992
–10
10
30
50
TEMPERATURE (°C)
70
90
4078x G03
IUSB Pin Voltage vs Temperature
(Constant-Current Mode)
1.008
1.006
1.004
I
BAT
(mA)
V
IUSB
(V)
1.002
1.000
0.998
0.996
0.994
0.992
–10
10
30
50
TEMPERATURE (°C)
70
90
4078x G04
Charge Current
vs IDC Pin Voltage
900
800
700
600
500
400
300
200
100
0
0
0.2
0.4
0.6
0.8
V
IDC
(V)
1.0
1.2
R
IDC
= 10k
R
IDC
= 2k
I
BAT
(mA)
R
IDC
= 1.24k
V
DCIN
= 5V
900
800
Charge Current
vs IUSB Pin Voltage
V
USBIN
= 5V
R
IUSB
= 1.24k
700
600
500
400
300
200
100
0
0
0.2
0.4
0.6
0.8
V
IUSB
(V)
1.0
1.2
R
IUSB
= 10k
R
IUSB
= 2k
V
USBIN
= 5V
4078x G05
4078x G06
⎯
P
⎯
W
⎯
R Pin I-V Curve
60
50
40
30
20
10
0
0
1
2
3
V
PWR
(V)
4078x G07
⎯
CH
⎯
R
⎯
G Pin I-V Curve
⎯
60
50
40
I
CHRG
(mA)
4
5
6
30
20
10
0
0
1
2
3
V
CHRG
(V)
4078x G08
V
DCIN
= V
USBIN
= 5V
V
DCIN
= V
USBIN
= 5V
I
PWR
(mA)
4
5
6
4078xf
4
LTC4078X
TYPICAL PERFORMANCE CHARACTERISTICS
Charge Current
vs Ambient Temperature
1000
900
800
700
I
BAT
(mA)
I
BAT
(mA)
600
500
400
300
200 V
DCIN
= V
USBIN
= 5V
V
BAT
= 4V
100
θ
JA
= 30°C/W
0
70
50
30
90
–10 10
TEMPERATURE (°C)
R
IDC
= R
IUSB
= 2k
R
IDC
= 1.24k
900
800
700
600
500
400
300
200
100
110
130
4078x G10
T
A
= 25°C, unless otherwise specified.
Charge Current
vs Supply Voltage
1000
Charge Current vs Battery Voltage
800
I
BAT
(mA)
R
IDC
= 1.24k
V
BAT
= 4V
θ
JA
= 30°C/W
4.5
5.0
5.5 6.0 6.5
V
DCIN
(V)
7.0
7.5
8.0
600
400
200
0
4.0
0
2.4
V
DCIN
= V
USBIN
= 5V
R
IDC
= 1.24k
θ
JA
= 30°C/W
2.7
3.0
3.3 3.6
V
BAT
(V)
3.9
4.2
4.5
4078x G11
4078x G12
DCIN Power FET On-Resistance
vs Temperature
800
750
700
650
600
550
500
–10
V
BAT
= 4V
I
BAT
= 200mA
900
850
800
750
700
650
USBIN Power FET On-Resistance
vs Temperature
V
BAT
= 4V
I
BAT
= 200mA
1000
980
960
R
DS(ON)
(mΩ)
V
ENABLE
(V)
940
920
900
880
ENABLE Pin Threshold Voltage
(On-to-Off) vs Temperature
V
DCIN
= V
USBIN
= 5V
R
DS(ON)
(mΩ)
10
30
50
TEMPERATURE (°C)
70
90
4078x G13
600
–10
10
30
50
TEMPERATURE (°C)
70
90
4078x G14
860
–10
10
30
50
TEMPERATURE (°C)
70
90
4078x G15
USBIN Shutdown Current
vs Temperature
60
55
50
I
USBIN
(µA)
45
40
35
30
25
20
–50
–25
0
25
50
TEMPERATURE (°C)
75
100
V
USBIN
= 4.3V
V
USBIN
= 5V
I
DCIN
(µA)
V
ENABLE
= 0V
60
55
50
45
40
35
30
25
DCIN Shutdown Current
vs Temperature
V
ENABLE
= 5V
2.4
2.3
V
DCIN
= 5V
R
ENABLE
(MΩ)
V
DCIN
= 4.3V
–25
0
25
50
TEMPERATURE (°C)
75
100
2.2
2.1
2.0
1.9
1.8
1.7
ENABLE Pin Pulldown Resistance
vs Temperature
20
–50
1.6
–50
–25
0
25
50
TEMPERATURE (°C)
75
100
4078x G16
4078x G17
4078x G18
4078xf
5
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