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PDF LTC4054L-4.2 Data sheet ( Hoja de datos )
| Número de pieza | LTC4054L-4.2 | |
| Descripción | Standalone Linear Li-Ion Battery Charger | |
| Fabricantes | Linear Technology | |
| Logotipo |  |
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LTC4054L-4.2
150mA Standalone Linear
Li-Ion Battery Charger in ThinSOT
FEATURES
s Programmable Charge Current Range:
10mA to 150mA
s No External MOSFET, Sense Resistor or Blocking
Diode Required
s Complete Linear Charger in ThinSOTTM Package for
Single Cell/Coin Cell Lithium-Ion Batteries
s Constant-Current/Constant-Voltage Operation with
Thermal Regulation* to Maximize Charge Rate
Without Risk of Overheating
s Charges Single Cell Li-Ion Batteries Directly
from USB Port
s Preset 4.2V Charge Voltage with ±1% Accuracy
s Charge Current Monitor Output for Gas Gauging*
s Automatic Recharge
s Charge Status Output Pin
s C/10 Charge Termination
s 25µA Max Supply Current in Shutdown Mode
s 2.9V Trickle Charge Threshold
s Soft-Start Limits Inrush Current
s Available in a 6-Lead Low Profile (1mm)
SOT-23 Package
U
APPLICATIO S
s Charger for Li-Ion Coin Cell Batteries
s Portable MP3 Players, Wireless Headsets
s Bluetooth Applications
s Multifunction Wristwatches
DESCRIPTIO
The LTC®4054L is a complete, constant-current/constant-
voltage linear charger for single cell lithium-ion batteries.
Its small size and ability to regulate low charge currents
make the LTC4054L especially well-suited for portable
applications using low capacity rechargeable lithium-ion
coin cells. Furthermore, the LTC4054L is specifically de-
signed to work within USB power specifications.
No external sense resistor is needed, and no blocking di-
ode is required due to the internal MOSFET architecture.
Thermal feedback regulates the charge current to eliminate
thermal overdesign. The charge voltage is fixed at 4.2V, and
the charge current can be programmed externally with a
single resistor. The LTC4054L automatically terminates a
charge cycle when the charge current drops to 1/10th the
programmed value after the final float voltage is reached.
When the input supply (wall adapter or USB supply) is
removed, the LTC4054L automatically enters a low cur-
rent state, dropping the battery drain current to less than
2µA. The LTC4054L can be put into shutdown mode, re-
ducing the supply current to 25µA.
Other features include charge current monitor, undervoltage
lockout, automatic recharge and a status pin to indicate
charge termination and the presence of an input voltage.
, LTC and LT are registered trademarks of Linear Technology Corporation.
ThinSOT is a trademark of Linear Technology Corporation.
*U.S. Patent No. 6,522,118
TYPICAL APPLICATIO
90mA Li-Ion Single Coin Cell Charger
VIN
4.5V TO 6.5V
1µF
4
VCC BAT 3
LTC4054L-4.2
5
PROG
GND
2
1.69k
90mA
4.2V
COIN CELL
Li-Ion
BATTERY
4054l42 TA01
Complete Charge Cycle (130mAh Battery)
100 4.4
90
CONSTANT
80 CURRENT
70
CONSTANT
VOLTAGE
4.3
4.2
4.1
60 4.0
50 3.9
40 3.8
30 3.7
20
VCC = 5V
θJA = 130°C/W
3.6
10 RPROG = 1.69k
3.5
TA = 25°C
0 3.4
0 0.25 0.5 0.75 1.0 1.25 1.5 1.75 2.0 2.25
TIME (HOURS)
4054l42 TA01b
4054l42f
1
1 page  
TYPICAL PERFOR A CE CHARACTERISTICS
CHRG Pin Current vs Temperature
(Weak Pull-Down State)
28
VCC = 5V
VBAT = 4.3V
25 VCHRG = 5V
22
19
16
13
10
–50 –25 0
25 50
TEMPERATURE (°C)
75 100
4054L G13
Trickle Charge Threshold
vs Temperature
3.000
VCC = 5V
2.975 RPROG = 1k
2.950
2.925
2.900
2.875
2.850
2.825
2.800
–50 –25
0
25 50 75 100
TEMPERATURE (°C)
4054L G16
Charge Current
vs Ambient Temperature
180
RPROG = 1k
150
120
VBAT = 4V
90 VCC = 5V
θJA = 125°C/W
60
ONSET OF
THERMAL
REGULATION
30
RPROG = 15k
0
–50 –25 0 25 50 75
TEMPERATURE (°C)
100 125
4054L G19
Trickle Charge Current
vs Temperature
15
RPROG = 1k
12
9
VCC = 5V
VBAT = 2.5V
6
3
RPROG = 15k
0
–50 –25
0
25 50
TEMPERATURE (°C)
75 100
4054L G14
Charge Current vs Battery Voltage
160
120
VCC = 5V
80
RPROG = 1k
TA = 25°C
θJA = 125°C/W
40
0
2.7 3.0 3.3 3.6 3.9 4.2 4.5
VBAT (V)
4054L G17
Recharge Voltage Threshold
vs Temperature
4.11
VCC = 5V
RPROG = 1k
4.09
4.07
4.05
4.03
4.01
3.99
–50 –25 0
25 50
TEMPERATURE (°C)
75 100
4054L G20
LTC4054L-4.2
Trickle Charge Current
vs Supply Voltage
15
RPROG = 1k
12
9
VBAT = 2.5V
TA = 25°C
6
3
RPROG = 15k
0
4 4.5 5 5.5 6
VCC (V)
6.5 7
4054L G15
Charge Current vs Supply Voltage
200
VBAT = 4V
TA = 25°C
160 θJA = 125°C/W
RPROG = 1k
120
80
40
RPROG = 15k
0
4 4.5 5 5.5 6
VCC (V)
6.5 7
4054L G18
Power FET “ON” Resistance
vs Temperature
1.8
VCC = 4.1V
VBAT = 4V
1.6 RPROG = 1k
1.4
1.2
1.0
0.8
–50 –25
0 25 50 75
TEMPERATURE (°C)
100 125
4054L G21
4054l42f
5
5 Page 
LTC4054L-4.2
APPLICATIO S I FOR ATIO
Stability Considerations
The constant-voltage mode feedback loop is stable with-
out an output capacitor provided a battery is connected to
the charger output. With no battery present, an output
capacitor is recommended to reduce ripple voltage. When
using high value, low ESR ceramic capacitors, it is recom-
mended to add a 1Ω resistor in series with the capacitor.
No series resistor is needed if tantalum capacitors are
used.
In constant-current mode, the PROG pin is in the feedback
loop, not the battery. The constant-current mode stability
is affected by the impedance at the PROG pin. With no
additional capacitance on the PROG pin, the charger is
stable with program resistor values as high as 20k. How-
ever, additional capacitance on this node reduces the
maximum allowed program resistor. The pole frequency
at the PROG pin should be kept above 100kHz. Therefore,
if the PROG pin is loaded with a capacitance, CPROG, the
following equation can be used to calculate the maximum
resistance value for RPROG:
RPROG
≤
2π
1
• 105 •
CPROG
Average, rather than instantaneous, charge current may
be of interest to the user. For example, if a switching power
supply operating in low current mode is connected in
parallel with the battery, the average current being pulled
out of the BAT pin is typically of more interest than the
instantaneous current pulses. In such a case, a simple RC
filter can be used on the PROG pin to measure the average
battery current as shown in Figure 2. A 10k resistor has
been added between the PROG pin and the filter capacitor
to ensure stability.
Power Dissipation
The conditions that cause the LTC4054L to reduce charge
current through thermal feedback can be approximated by
considering the power dissipated in the IC. Nearly all of
this power dissipation is generated from the internal
MOSFET—this is calculated to be approximately:
PD = (VCC – VBAT) • IBAT
where PD is the power dissipated, VCC is the input supply
voltage, VBAT is the battery voltage and IBAT is the charge
current. The approximate ambient temperature at which
the thermal feedback begins to protect the IC is:
TA = 120°C – PDθJA
TA = 120°C – (VCC – VBAT) • IBAT • θJA
PROG
LTC4054L
GND
10k
RPROG
CHARGE
CURRENT
MONITOR
CIRCUITRY
CFILTER
4054L42 F02
Figure 2. Isolating Capacitive Load on PROG Pin and Filtering
4054l42f
11
11 Page | ||
| Páginas | Total 16 Páginas | |
| PDF Descargar | [ Datasheet LTC4054L-4.2.PDF ] | |
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