LY3085A
800mA Lithium Ion Battery Linear Charger
LY3085A
General Description
LY3085A is a complete constant-current/constant
voltage linear charger for single cell lithium-ion
batteries. Furthermore the
LY3085A is specifically
Features
●Protection of battery cell reverse connection
●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 Rate Without risk
of overheating.
● Preset 4.2V charge voltage with ±
1% accuracy
● Automatic Recharge
●Charges Single Cell Li-Ion Batteries Directly from
USB Port
●C/10 charge termination
● 55μA supply current in shutdown
● 2.9V trickle current charge threshold
● Soft-Start limits inrush current
●Charge Status Output Pin
●Available in SOT23-5 Package
designed to work within USB power specifications.
No external sense resistor is needed and no
blocking diode is required due to the internal
PMOSFET 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
LY3085A
automatically
terminates the charge cycle when the charge current
drops to 1/10
th
the programmed value after the final
float voltage is reached.
When the input supply (wall adapter or USB supply)
is removed the LY3085A automatically enters a low
current state dropping the battery drain current to less
than 2μA.The LY3085A can be put into shutdown
mode reducing the supply current to 55μA.
Other features include charge current monitor,
undervoltage lockout, automatic recharge and a
status.
Applications
●Cellular Telephones, PDAs, MP3 Players
●Charging Docks and Cradles
●Bluetooth Applications
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15
LY3085A
600mA Single Cell Li-Ion Charger
V
IN
4.5V TO 6.5V
Typical charge cycle（750mAh batter
700
LY3085A
4.75
CONSTANT CURRENT
CONSTANT 4.5
CONSTANT
VOLTAGAE
POWER
4.25
4.0
V
CC
=5V
3.75
3.5
3.25
3.0
2.0
CHARGE CURRENT(mA)
BATTERY VOLTAGE(V)
4
VCC
BAT
3
600
500
400
300
200
100
0
0
LY3085A
GND
1μF
PROG
5
600mA
4.2V
1.65K
Li-Ion
BATTERY
2
θ
JA
=130℃/W
R
PROG
=1.65K CHARGE
T
A
=25℃
TERMINATED
0.25 0.5 0.75 1.0 1.25 1.5 1.75
TIME(HOURS)
Pin Configuration
CHRG 1
GND 2
LY3085A
5 PROG
BAT 3
4 VCC
封装½式：SOT23-5
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LY3085A
Pin Assignment
LY3085A
Pin Num.
Symbol
Open-Drain charge status output
1
CHRG
When the battery is being charged, the
otherwise,
2
GND
Ground
Battery connection Pin
Connect the positive terminal of the battery to this pin. Dropping BAT pin’s current to
3
BAT
less than 2μA when IC in disable mode or in sleep mode. BAT pin provides charge
current to the battery and provides regulation voltage of 4.2V.
Positive input supply voltage
4
VCC
Provides power to the internal circuit. When V
CC
drops to within 80mV of the BAT pin
voltage, the LY3085A enters low power sleep mode, dropping I
BAT
to less than 2μA.
Constant Charge Current Setting and Charge Current Monitor Pin
The charge current is programmed by connecting a resistor R
PROG
from this pin to
GND. When in precharge mode, the PROG pin’s voltage is regulated to 0.1V. When
5
PROG
charging in constant-current mode this pin’s voltage is regulated to 1V. In all modes
during charging, the voltage on this pin can be used to measure the charge current
using the following formula:
pin is pulled low by an internal switch,
Function
pin is in high impedance state.
I
BAT
=
V
PROG
*1100
R
PROG
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FAX:0755-82985153
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LY3085A
Block Diagram
LY3085A
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LY3085A
Absolute Maximum Ratings
Parameter
Input supply voltage : V
CC
PROG pin voltage
BAT pin voltage
pin voltage
BAT pin current
PROG pin current
Maximum junction temperature
Operating ambient temperature :T
opa
Storage temperature :T
str
Soldering temperature and time
Rating
-0.3½8
-0.3½VCC+0.3
-0.3½7
-0.3½10
800
1200
145
-40½85
-65½125
+260（Recommended 10S）
Unit
V
V
V
V
mA
μA
℃
℃
℃
℃
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.
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Page 5 of
15
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