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PDF LTC4078 Data sheet ( Hoja de datos )
| Número de pieza | LTC4078 | |
| Descripción | Dual Input Li-Ion Battery Charger | |
| Fabricantes | Linear | |
| Logotipo |  |
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LTC4078/LTC4078X
Dual Input Li-Ion Battery
Charger with Overvoltage Protection
FEATURES
n 22V Maximum Voltage for Wall Adapter and
USB Inputs
n Charge Single-Cell Li-Ion Batteries from Wall
Adapter and USB Inputs
n Automatic Input Power Detection and Selection
n Charge Current Programmable Up to 950mA from
Wall Adapter Input
n Overvoltage Lockout for Wall Adapter and USB Inputs
n Battery Detection Input Disables Charger When No
Battery is Present
n No External MOSFET, Sense Resistor or Blocking
Diode Needed
n Thermal Regulation Maximizes Charge Rate Without
Risk of Overheating*
n Preset Charge Voltage with ±0.6% Accuracy
n Programmable Charge Current Termination
n 40μA USB Suspend Current in Shutdown
n Charge Status Output
n Automatic Recharge
n Available Without Trickle Charge (LTC4078X)
n Available in a Thermally Enhanced, Low Profile
(0.75mm) 10-Lead (3mm × 3mm) DFN Package
APPLICATIONS
n Cellular Telephones
n Handheld Computers
n Portable MP3 Players
n Digital Cameras
DESCRIPTION
The LTC®4078/LTC4078X are standalone linear chargers
that are capable of charging a single-cell Li-Ion/Polymer
battery from both wall adapter and USB inputs. The chargers
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
LTC4078/LTC4078X feature 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 con-
ditions. The float voltage is fixed at 4.2V and the charge
current is programmed with an external resistor. The
LTC4078/LTC4078X terminate 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.
L, 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.
TYPICAL APPLICATION
High Voltage Dual Input Battery Charger
for Li-Ion Battery Pack
WALL
ADAPTER
USB
PORT
1μF
LTC4078
DCIN
BAT
USBIN BATDET
1μF IUSB
2k
1%
IDC
1.24k
ITERM
GND
1%
800mA (WALL)
500mA (USB)
+
3.9k
4.2V
Li-Ion
BATTERY
PACK
2k
1%
4078X TA01
Charger Current vs Supply Voltage
900
RIDC = 1.24k
800 RIUSB = 2k
VBAT = 3.5V
700 VBATDET = 0V
600 CHARGE FROM DCIN
500
400
CHARGE
300 FROM USBIN
200
100
0
2 3 4 5 6 7 8 19 20
SUPPLY VOLTAGE (V)
4078x TA01b
4078xfb
1
1 page  
LTC4078/LTC4078X
TYPICAL PERFORMANCE CHARACTERISTICS TA = 25°C, unless otherwise specified.
Charge Current
vs Ambient Temperature
1000
900
RIDC = 1.24k
800
700
600
RIDC = RIUSB = 2k
500
400
300
200 VDCIN = VUSBIN = 5V
100 VBAT = 4V
θJA = 30°C/W
0
–10 10 30 50
70
90
TEMPERATURE (°C)
110 130
4078x G10
DCIN Power FET On-Resistance
vs Temperature
800
VBAT = 4V
IBAT = 200mA
750
700
650
600
550
500
–10
10 30 50 70 90
TEMPERATURE (°C)
4078x G13
USBIN Shutdown Current
vs Temperature
60
VENABLE = 0V
55
50 VUSBIN = 5V
45
40
35 VUSBIN = 4.3V
30
25
20
–50 –25
0
25 50 75 100
TEMPERATURE (°C)
4078x G16
Charge Current
vs Supply Voltage
900
800
700
600
500
400
300
200
RIDC = 1.24k
100 VBAT = 4V
θJA = 30°C/W
0
4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0
VDCIN (V)
4078x G11
USBIN Power FET On-Resistance
vs Temperature
900
VBAT = 4V
IBAT = 200mA
850
800
750
700
650
600
–10
10 30 50 70 90
TEMPERATURE (°C)
4078x G14
DCIN Shutdown Current
vs Temperature
60
VENABLE = 5V
55
50 VDCIN = 5V
45
40
35
30 VDCIN = 4.3V
25
20
–50 –25
0
25 50 75 100
TEMPERATURE (°C)
4078x G17
Charge Current vs Battery Voltage
1000
800
600
400
200 VDCIN = VUSBIN = 5V
RIDC = 1.24k
θJA = 30°C/W
0
2.4 2.7 3.0 3.3 3.6 3.9 4.2 4.5
VBAT (V)
4078x G12
ENABLE Pin Threshold Voltage
(On-to-Off) vs Temperature
1000
VDCIN = VUSBIN = 5V
980
960
940
920
900
880
860
–10
10 30 50 70 90
TEMPERATURE (°C)
4078x G15
ENABLE Pin Pulldown Resistance
vs Temperature
2.4
2.3
2.2
2.1
2.0
1.9
1.8
1.7
1.6
–50 –25
0
25 50 75 100
TEMPERATURE (°C)
4078x G18
4078xfb
5
5 Page 
LTC4078/LTC4078X
OPERATION
This output is strong enough to drive an LED. If no valid
voltage is applied at either pin, the PWR pin is high im-
pedance, indicating that the LTC4078/LTC4078X lack valid
input voltage (see Table 1) to charge the battery.
Thermal Limiting
An internal thermal feedback loop reduces the programmed
charge current if the die temperature attempts to rise above
a preset value of approximately 120°C. This feature protects
the LTC4078/LTC4078X from excessive temperature and
allows the user to push the limits of the power handling
capability of a given circuit board without risk of damag-
ing the device. The charge current can be set according
to typical (not worst-case) ambient temperature with the
assurance that the charger will automatically reduce the
current in worst case conditions. DFN package power
considerations are discussed further in the Applications
Information section.
DCIN POWER REMOVED
ENABLE = LOW
NO POWER
USB POWER REMOVED
POWER APPLIED
ENABLE = HIGH
6V > DCIN > 4.15V
AND DCIN > BAT
YES
BATDET < 1.75V
NO
NO
YES
FULL CURRENT (BAT > 2.9V)
1/10TH FULL CURRENT
(BAT < 2.9V)*
CHRG STATE: PULLDOWN
IBAT < ITERMINATE
IN VOLTAGE MODE
BAT < 4.075V
STANDBY MODE
(DCIN)
NO CHARGE CURRENT
CHRG STATE: Hi-Z
YES DCIN > 4.15V
AND DCIN > BAT
NO
NO 6V > USBIN > 3.95V
AND USBIN > BAT
YES
NO
BATDET < 1.75V
YES
FULL CURRENT (BAT > 2.9V)
1/10TH FULL CURRENT
(BAT < 2.9V)*
CHRG STATE: PULLDOWN
IBAT < ITERMINATE
IN VOLTAGE MODE
STANDBY MODE
(USBIN)
NO CHARGE CURRENT
CHRG STATE: Hi-Z
BAT < 4.075V
*LTC4078 ONLY
SHUTDOWN MODE
(DCIN)
CHRG STATE: Hi-Z
SHUTDOWN MODE
(USBIN)
CHRG STATE: Hi-Z
4078X F01
Figure 1. LTC4078 State Diagram of a Charge Cycle
4078xfb
11
11 Page | ||
| Páginas | Total 16 Páginas | |
| PDF Descargar | [ Datasheet LTC4078.PDF ] | |
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