XT2055
Standalone Linear Li-Ion Battery Charger with Thermal Regulation
■
General Description
The XT2055 is a complete constant-current /constant
-voltage linear charger for single cell lithium-ion batteries.
Its Thin SOT package and low external component count
make the XT2055 ideally suited for portable applications.
Furthermore, the XT2055 is specifically designed to work
within USB power specifications.
No external sense resistor is needed, and no blocking
diode is required due to the internal MOSFET architecture.
Thermal feedback regulates the charge current to limit the
die temperature during high power operation or high
ambient temperature. The charge voltage is fixed at 4.2V,
and the charge current can be programmed externally with
a single resistor. The XT2055 automatically terminates the
charge cycle when the charge current drops to 1/10 the
programmed value after the final float voltage is reached.
When the input supply (wall adapter or USB supply) is
removed, the XT2055 automatically enters a low current
state, dropping the battery drain current to less than 2µA.
The XT2055 can be put into shutdown mode, reducing the
supply current to 25µA.
Other
features
include
charge
current
monitor,
th
■
Applications
Cellular Telephones, PDAs, MP3 Players
Bluetooth Applications
■
Features
Programmable charge current up to 500mA
No MOSFET, sense resistor or blocking diode
required
Complete linear charger in thinsot package for single
cell lithium-ion batteries
Constant-current/constant-voltage
operation
with
thermal regulation to maximize charge rate without
risk of overheating
Charges single cell li-ion batteries directly from USB
port
Preset 4.2V charge voltage with
1%
accuracy
Charge current monitor output for gas gaugin
Charge status output pin
C/10 charge termination
25µA supply current in shutdown
2.9V trickle charge threshold (XT2055)
Soft-start limits inrush current
Available in 6-Lead SOT-23
under-voltage lockout, automatic recharge and a status pin
to indicate charge termination and the presence of an input
voltage.
■
Package
SOT-23-6L
■
Typical Application Circuit
VIN
1K
RLED
GLED
VIN
BAT
VBAT
C1
C2
DONE
CHRG
GND
PROG
R
PROG
GND
GND
Rev.1.1
—
Feb. 29. 2016
1
http://www.silinktek.com
XT2055
■
Pin Function
CHRG (Pin 1):
Open-Drain Charge Status Output. When the battery is charging, the CHRG pin is pulled low by an internal
N-channel MOSFET. When the charge cycle is completed, a weak pull-down of approximately 20µA is connected to the
CHRG pin, indicating an “AC present” condition. When the XT2055 detects an under voltage lockout condition, CHRG is
forced high impedance.
GND (Pin 2):
Ground.
BAT (Pin 3):
Charge current output. Provides charge current to the battery and regulates the final float voltage to 4.2V. An
internal precision resistor divider from this pin sets the float voltage which is disconnected in shutdown mode.
VCC (Pin 4):
Positive input supply voltage. Provides power to the charger. VCC should be bypassed with at least a 1µF
capacitor. When VCC drops to within 30mV of the BAT pin voltage, the XT2055 enters shutdown mode, dropping IBAT to
less than 2µA.
DONE (Pin5):
Full indication output, when fully charged, DONE port is an internal N-channel MOSFET placed in low
position. In the charging process, low-power lock condition is detected; the input is too high to detect locking conditions,
DONE-Z state.
PROG (Pin 5):
Charge current program, charge current monitor and shutdown pin. The charge current is programmed by
connecting a 1% resistor, RPROG to ground. When charging in constant-current mode, this pin servos to 1V. In all modes,
the voltage on this pin can be used to measure the charge current using the following formula:
IBAT = (VPROG/RPROG) × 1000
The PROG pin can also be used to shut down the charger. Disconnecting the program resistor from ground allows a 3µA
current to pull the PROG pin high. When it reaches the 1.21V shutdown threshold voltage, the charger enters shutdown
mode, charging stops and the input supply current drops to 25µA. This pin is also clamped to approximately 2.4V. Driving
this pin to voltages beyond the clamp voltage will draw currents as high as 1.5mA. Reconnecting RPROG to ground will
return the charger to normal operation.
■
Marking Rule
SOT-23-6L
① ② ③ ④
. . . ..
.
SOT-23-6L
(TOP VIEW)
①
Represents the product name
Symbol
2
Product Name
XT2055◆◆◆◆◆
Rev.1.1
—
Feb. 29. 2016
3
http://www.silinktek.com
XT2055
②
Represents the type of the trickle charge voltage and CHRG pin
Symbol
C
D
Product Series
XT2055X◆◆◆◆
XT2055Y◆◆◆◆
Description
Without trickle charge
With trickle charge
③
Represents the regulator output voltage
Symbol
A
B
C
D
E
F
④
Represents the assembly lot No.
Voltage
4.0
4.025
4.05
4.075
4.1
4.125
Symbol
H
K
L
M
N
P
Voltage
4.150
4.175
4.2
4.225
4.250
4.275
0-9，A-Z; 0-9，A-Z mirror writing，repeated（G，I，J，O，Q，W exception）
■
Absolute Maximum Ratings
Parameter
Input Supply Voltage
PROG pin Voltage
BAT pin Voltage
CHAG pin Voltage
Power Dissipation
BAT pin Current
PROG pin Current
Operating Ambient Temperature
Storage Temperature
Symbol
V
cc
Vprog
Vbat
Vchrg
P
D
Ibat
Iprog
Topa
Tstr
Maximum Rating
V
SS
-0.3½V
SS
+10
V
SS
-0.3½V
cc
+0.3
Vss-0.3½7
V
SS
-0.3½V
SS
+10
SOT-23-6L
500
800
-40½+85
-65½+125
250
mW
mA
µA
°C
V
Unit
Caution:
The absolute maximum ratings are rated values exceeding which the product could suffer physical damage.
These values must therefore not be exceeded under any conditions.
Rev.1.1
—
Feb. 29. 2016
4
http://www.silinktek.com
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