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A4054A Datasheet Preview

A4054A Datasheet

800mA STANDALONE LINEAR Li-ion BATTERY CHARGER

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A4054A pdf
AiT Semiconductor Inc.
www.ait-ic.com
A4054A
800mA STANDALONE LINEAR Li-ion BATTERY CHARGER
THERMAL REGULATION
DESCRIPTION
The A4054A is a complete constant current / constant
voltage linear charger for single cell Lithium-Ion
batteries. 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 A4054A 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 A4054A automatically enters a low
current state, dropping the battery drain current to
less than 2μA. The A4054A can be put into shutdown
mode, reducing the supply current to 25μA. Other
features include charge current monitor, under-voltage
lockout, automatic recharge and a status pin to
indicate charge termination and the presence of an
input voltage. A4054A will check the battery voltage
first, it will not start charging unless the battery
voltage is below the auto-rechrage threshold.
The A4054A is available in SOT-25 packages.
FEATURES
Programmable Charge Current Up to 800mA
No MOSFET, Sense Resistor or Blocking
Diode Required
Preset 4.2V Charge Voltage with ±1%
Accuracy
Charge Current Monitor Output for Gas
Gauging
Thermal Regulation Maximizes Charge Rate
Without Risk of Overheating
Charges Single Cell Li-Ion Batteries Directly
from USB Port
Over-Voltage Protect
Automatic Recharge
Charge Status Output Pin
C/10 Charge Termination
25μA Supply Current in Shutdown
2.9V Trickle Charge Threshold
Soft-Start Limits Inrush Current
Available in SOT-25 Packages
APPLICATION
Cellular and Smart Phones
Charging Docks and Cradles
Blue Tooth Applications
PDAs
MP3/MP4/MP5 Players
ORDERING INFORMATION
TYPICAL APPLICATION
Package Type
Part Number
SOT-25
A4054AE5R
E5
A4054AE5VR
Note
R: Tape & Reel
V: Halogen free Package
AiT provides all RoHS products
Suffix “V” means Halogen free Package
REV1.1
- DEC 2008 RELEASE, JUN 2012 UPDATED -
-1-



AiT Semiconductor
AiT Semiconductor

A4054A Datasheet Preview

A4054A Datasheet

800mA STANDALONE LINEAR Li-ion BATTERY CHARGER

No Preview Available !

A4054A pdf
AiT Semiconductor Inc.
www.ait-ic.com
A4054A
800mA STANDALONE LINEAR Li-ion BATTERY CHARGER
THERMAL REGULATION
PIN DESCRIPTION
Pin #
1
2
3
4
5
Symbol
CHRGb
GND
BAT
VCC
PROG
Top View
Function
Open-Drain Charge Status Output. When the battery is charging, the CHRGb pin is
pulled low by an internal N-channel MOSFET. When the charge cycle is completed, a
weak pull-down of approximately 12μA is connected to the CHRGb pin, indicating an
“AC present” condition. When the A4054A detects an under-voltage lockout condition,
CHRGb is forced high impedance.
Ground
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.
Positive Input Supply Voltage. Provides power to the charger. VCC can range from
4.25V to 6.5V and should be bypassed with at least a 1μF capacitor. When VCC drops
to within 30mV of the BAT pin voltage, the A4054A enters shutdown mode, dropping
IBAT to less than 2μA.
Charge Current Program, Charge Current Monitor and Shutdown Pin. The charge
current is Programmed by connecting a 1% resistor, RPROG, from this pin 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.
REV1.1
- DEC 2008 RELEASE, JUN 2012 UPDATED -
-2-


Part Number A4054A
Description 800mA STANDALONE LINEAR Li-ion BATTERY CHARGER
Maker AiT Semiconductor
Total Page 20 Pages
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