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PDF LTC4055 Data sheet ( Hoja de datos )
| Número de pieza | LTC4055 | |
| Descripción | USB Power Controller and Li-Ion Linear Charger | |
| Fabricantes | Linear Technology | |
| Logotipo |  |
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LTC4055/LTC4055-1
USB Power Controller
and Li-Ion Charger
FEATURES
DESCRIPTION
n Charges Single-Cell Li-Ion Batteries Directly from
USB Port
n Load Dependent Charging Guarantees USB Input
Current Compliance
n Automatic Battery Switchover When Input Supply is
Removed
n Constant-Current/Constant-Voltage Operation with
Thermal Feedback to Maximize Charging Rate
Without Risk of Overheating*
n Selectable 500mA/100mA Current Limit
n Low Loss Full PowerPath™ Control with Ideal Diode
Operation (Reverse Current Blocking)
n Preset 4.2V Charge Voltage with 0.8% Accuracy
(4.1V for LTC4055-1)
n 4.1V Float Voltage (LTC4055-1) Improves Battery Life
and High Temperature Safety Margin
n USB-Compliant Suspend Mode
n Programmable Charge Current and Termination Timer
n Soft-Start Limits Inrush Current
n NTC Thermistor Input for Temperature Qualified
Charging
n Tiny (4mm × 4mm × 0.75mm) QFN Package
APPLICATIONS
n Portable USB Devices: Cameras, MP3 Players, PDAs
L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
PowerPath is a trademark of Linear Technology Corporation. All other trademarks are the
property of their respective owners. *Protected by U.S. Patent, including 6522118.
The LTC®4055/LTC4055-1 are USB power manager and
Li-Ion battery chargers designed to work in portable
battery-powered applications. The parts manage and limit
the total current used by the USB peripheral for operation
and battery charging. Depending on the state of the current
select pin (HPWR), total input current can be limited to
either 100mA or 500mA. The voltage drop from the USB
supply or battery to the USB peripheral is typically less than
100mV at 400mA and 20mV at 80mA. Other management
features include: automatic switchover to battery when
input is removed, inrush current limiting, reverse current
blocking, undervoltage lockout and thermal shutdown.
The LTC4055/LTC4055-1 include a complete constant-
current/constant-voltage linear charger for single-cell
Li-ion batteries. The float voltage applied to the battery
is held to a tight 0.8% tolerance, and charge current is
programmable using an external resistor to ground. Fully
discharged cells are automatically trickle charged at 10%
of the programmed current until the cell voltage exceeds
2.8V. Total charge time is programmable by an external
capacitor to ground. When the battery drops 100mV below
the float voltage, automatic recharging of the battery
occurs. Also featured is an NTC thermistor input used to
monitor battery temperature while charging.
The LTC4055/LTC4055-1 are available in a 16-pin low
profile (4mm × 4mm) QFN package.
TYPICAL APPLICATION
5V (NOM)
FROM USB
CABLE VBUS
1Ω
10μF
SUSPEND USB POWER
500mA/100mA SELECT
IN1
IN2
VNTC
NTC
WALL
LTC4055
SHDN
SUSP
HPWR
TIMER PROG CLPROG
OUT
BAT +
CHRG
ACPR
GND
Li-Ion
CELL
0.1μF
97.6k 97.6k
4055 TA01
TO SYSTEM
LOADS
10μF
Input and Battery Current vs Load Current
RPROG = RCLPROG = 97.6k
600
500 IIN
400
ILOAD
300
200
IBAT
CHARGING
100
0
–100
0
IBAT
(IDEAL DIODE)
100 200 300 400 500 600
ILOAD (mA)
4055 TA02
4055fb
1
1 page  
LTC4055/LTC4055-1
TYPICAL PERFORMANCE CHARACTERISTICS
Input Supply Current
vs Temperature
900
VIN = 5V
800 VBAT = 4.2V
RPROG = RCLPROG = 100k
700
600
500
400
300
200
100
0
–50
–25 0 25 50
TEMPERATURE (°C)
75 100
4055 G01
Input Current Limit
vs Temperature, HPWR = 5V
515
VIN = 5V
VBAT = 3.5V
505 RPROG = RCLPROG = 100k
495
485
475
465
–50 –25
0 25 50 75
TEMPERATURE (°C)
100 125
4055 G04
PROG Pin Voltage vs Temperature
1.020
VIN = 5V
1.015 RPROG = 100k
1.010
1.005
1.000
0.995
0.990
0.985
0.980
–50 –25
0
25 50 75
TEMPERATURE (°C)
100
4055 G07
Input Supply Current
vs Temperature (Suspend Mode)
60
VIN = 5V
VBAT = 4.2V
50 RPROG = RCLPROG = 100k
SUSP = 5V
40
30
20
10
0
–50 –25 0
25 50
TEMPERATURE (°C)
75 100
4055 G02
Input Current Limit
vs Temperature, HPWR = 0V
105.0
102.5
VIN = 5V
VBAT = 3.5V
RPROG = RCLPROG = 100k
100.0
97.5
95.0
92.5
90.0
–50 –25
0 25 50 75
TEMPERATURE (°C)
100 125
4055 G05
CLPROG Pin Voltage
vs Temperature
1.020
VIN = 5V
1.015 RCLPROG = 100k
1.010
1.005
1.000
0.995
0.990
0.985
0.980
–50 –25 0
25 50 75 100
TEMPERATURE (°C)
4055 G08
Battery Drain Current
vs Temperature
(BAT Powers OUT, No Load)
70
VIN = 0V
60 VBAT = 4.2V
50
40
30
20
10
0
–50 –25
0 25 50
TEMPERATURE (°C)
75 100
4055 G03
RON vs Temperature
250
ILOAD = 400mA
225
VIN = 5V
200
VIN = 4.5V
175
VIN = 5.5V
150
125
100
–50 –25
0 25 50 75
TEMPERATURE (°C)
100 125
4055 G06
Battery Regulated Output (Float)
Voltage vs Temperature
4.3
VIN = 5V
LTC4055
4.2
LTC4055-1
4.1
4.0
–50 –25 0
25 50 75 100
TEMPERATURE (oC)
4055 G09
4055fb
5
5 Page 
LTC4055/LTC4055-1
OPERATION
The LTC4055/LTC4055-1are complete PowerPath control-
lers for battery-powered USB applications. The LTC4055/
LTC4055-1 are designed to provide device power and Li-ion
battery charging from the USB VBUS while maintaining
the current limits as specified in the USB specification.
This is accomplished by reducing battery charge current
as output/load current is increased. In this scenario, the
available bus current is maximized in an effort to minimize
battery charge time.
An ideal diode function provides power from the battery
when output/load current exceeds the input current limit
set for the part or when input power is removed. The
advantage to powering the load through the ideal diode
(rather than connecting the load directly to the battery)
is that when the bus is connected and the battery is fully
charged, the battery remains fully charged until bus power
is removed. Once bus power is removed the output drops
until the ideal diode is forward biased. The forward biased
ideal diode will then provide the output power to the load
from the battery.
Another advantage to powering the load from the bus when
the bus is available is in cases where the load is a switching
regulator. The input power to a switching regulator can be
thought of as constant. A higher voltage across a constant
power load will require less current. Less load current in
USB applications means more available charge current.
More charge current translates to shorter charge times.
The LTC4055/LTC4055-1 also have the ability to
accommodate power from a wall adapter. Wall adapter
power can be connected to the output (load side) of the
LTC4055/LTC4055-1 through an external device such as a
power Schottky or FET, as shown in Figure 1. The LTC4055/
LTC4055-1 have the unique ability to use the output, which
is powered by the wall adapter, as an alternate path to
charge the battery while providing power to the load. A
wall adapter comparator on the LTC4055/LTC4055-1 can
be configured to detect the presence of the wall adapter
and shut off the connection to the USB to prevent reverse
conduction out to the bus.
WALL
ADAPTER
VBUS
IN1
4
IN2
1
INPUT CHARGER
CONTROL
ENABLE
CURRENT LIMIT
CONTROL
ENABLE
OUTPUT CHARGER
CONTROL
ENABLE
OUT
3
LOAD
IDEAL
WALL
5
+
1V –
UVLO
Figure 1. Simplified Block Diagram—PowerPath
BAT
2
+
Li-Ion
4055 F01
4055fb
11
11 Page | ||
| Páginas | Total 24 Páginas | |
| PDF Descargar | [ Datasheet LTC4055.PDF ] | |
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