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A4055 Schematic ( PDF Datasheet ) - AiT Semiconductor

Teilenummer A4055
Beschreibung 800mA STANDALONE LINEAR LI-ION BATTERY CHARGER
Hersteller AiT Semiconductor
Logo AiT Semiconductor Logo 




Gesamt 19 Seiten
A4055 Datasheet, Funktion
AiT Semiconductor Inc.
www.ait-ic.com
A4055
LINEAR LI-ION BATTERY CHARGER
800mA STANDALONE LINEAR LI-ION BATTERY CHARGER
DESCRIPTION
The A4055 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 A4055
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 A4055 automatically enters a low
current state, dropping the battery drain current to
less than 2μA. The A4055 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.
The A4055 is available in SOT-25 Package
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 Package
ORDERING INFORMATION
Package Type
Part Number
SOT-25
A4055E5R
E5
A4055E5VR
Note
R: Tape & Reel
V: Halogen free package
AiT provides all RoHS products
Suffix V means Halogen free Package
APPLICATION
Cellular and Smart Phones
Charging Docks and Cradles
Blue Tooth Applications
PDAs
MP3/MP4/MP5 Players
TYPICAL APPLICATION
REV1.1
- OCT 2011 RELEASED, NOV 2014 UPDATED -
600mA Application Circuit
-1-






A4055 Datasheet, Funktion
AiT Semiconductor Inc.
www.ait-ic.com
A4055
LINEAR LI-ION BATTERY CHARGER
800mA STANDALONE LINEAR LI-ION BATTERY CHARGER
TYPICAL PERFORMANCE CHARACTERISTICS
Figure 1. PROG Pin Voltage vs. Supply Voltage
(Constant Current Mode)
Figure 2. PROG Pin Voltage vs. Temperature
Figure 3. Charge Current vs. PROG Pin Voltage
Figure 4. PROG Pin Pull-Up Current vs.
Temperature and Supply Voltage
Figure 5. PROG Pin Current vs. PROG Pin Voltage Figure 6. PROG Pin Current vs. PROG Pin Voltage
(Pull-Up Current)
(Clamp Current)
REV1.1
- OCT 2011 RELEASED, NOV 2014 UPDATED -
-6-

6 Page









A4055 pdf, datenblatt
AiT Semiconductor Inc.
www.ait-ic.com
A4055
LINEAR LI-ION BATTERY CHARGER
800mA STANDALONE LINEAR LI-ION BATTERY CHARGER
DEATAILED INFORMATION
The A4055 is a single cell Lithium-Ion battery charger using a constant-current / constant voltage algorithm.
It can deliver up to 800mA of charge current (using a good thermal PCB layout) with a final float voltage
accuracy of 1%. The A4055 includes an internal P-channel power MOSFET and thermal regulation circuitry.
No blocking diode or external current sense resistor is required; thus, the basic charger circuit requires only
two external components. Furthermore, the A4055 is capable of operating from a USB power source.
Normal Charge Cycle
A charge cycle begins when the voltage at the VCC pin rises above the UVLO threshold level and a 1%
program resistor is connected from the PROG pin to ground or when a battery is connected to the charger
output. If the BAT pin is less than 2.9V, the charger enters trickle charge mode. In this mode, the A4055
supplies approximately 1/10 the programmed charge current to bring the battery voltage up to a safe level for
full current charging.
When the BAT pin voltage rises above 2.9V, the charger enters constant-current mode, where the
programmed charge current is supplied to the battery. If the battery voltage is above 2.9V at power-on, A4055
enters the constant-current mode immediately. Refer to Figure 1.
When the BAT pin approaches the final float voltage (4.2V), the A4055 enters constant-voltage mode and the
charge current begins to decrease. When the charge current drops to 1/10 of the programmed value, the
charge cycle ends.
Programming Charge Current
The charge current is programmed using a single resistor from the PROG pin to ground. The battery charge
current is 1000 times the current out of the PROG pin. The program resistor and the charge current are
calculated using the following equations:
The charge current out of the BAT pin can be determined at any time by monitoring the PROG pin voltage
using the following equation:
REV1.1
- OCT 2011 RELEASED, NOV 2014 UPDATED -
- 12 -

12 Page





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