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PDF ( 数据手册 , 数据表 ) A4055

零件编号 A4055
描述 800mA STANDALONE LINEAR LI-ION BATTERY CHARGER
制造商 AiT Semiconductor
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A4055 数据手册, 描述, 功能
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 pdf, 数据表
AiT Semiconductor Inc.
www.ait-ic.com
A4055
LINEAR LI-ION BATTERY CHARGER
800mA STANDALONE LINEAR LI-ION BATTERY CHARGER
Figure 13. CHRG Pin Current vs.
Temperature(Weak Pull-Down State)
Figure 14. Trickle Charge Current vs. Temperature
Figure 15. Trickle Charge Current vs.
Supply Voltage
Figure 16. Trickle Charge Threshold vs.
Temperature
Figure 17. Charge Current vs. Battery Voltage
Figure 18. Charge Current vs. Supply Voltage
REV1.1
- OCT 2011 RELEASED, NOV 2014 UPDATED -
-8-







A4055 equivalent, schematic
AiT Semiconductor Inc.
www.ait-ic.com
A4055
LINEAR LI-ION BATTERY CHARGER
800mA STANDALONE LINEAR LI-ION BATTERY CHARGER
The A4055 can be used above 45°C ambient, but the charge current will be reduced from 400mA. The
approximate current at a given ambient temperature can be approximated by:
Using the previous example with an ambient temperature of 60°C, the charge current will be reduced to
approximately:
Moreover, when thermal feedback reduces the charge current, the voltage at the PROG pin is also reduced
proportionally as discussed in the Operation section. It is important to remember that A4055 applications do
not need to be designed for worst-case thermal conditions since the IC will automatically reduce power
dissipation when the junction temperature reaches approximately 120°C.
Thermal Considerations
The small size of the SOT package, it is very important to use a good thermal PC board layout to maximize
the available charge current. The thermal path for the heat generated by the IC is from the die to the copper
lead frame, through the package leads, (especially the ground lead) to the PC board copper. The PC board
copper is the heat sink. The footprint copper pads should be as wide as possible and expand out to larger
copper areas to spread and dissipate the heat to the surrounding ambient. Feed-through vias to inner or
backside copper layers are also useful in improving the overall thermal performance of the charger. Other
heat sources on the board, not related to the charger, must also be considered when designing a PC board
layout because they will affect overall temperature rise and the maximum charge current.
The following table lists thermal resistance for several different board sizes and copper areas.
All measurements were taken in still air on 3/32" FR-4 board with the device mounted on topside.
Table 1. Measured Thermal Resistance (2-Layer BoardNOTE6)
COPPER AREA
TOPSIDE
2500mm2
1000mm2
225mm2
100mm2
50mm2
BACKSIDE
2500mm2
2500mm2
2500mm2
2500mm2
2500mm2
BOARD ARE
2500mm2
2500mm2
2500mm2
2500mm2
2500mm2
THERMAL RESISTANCE
JUNCTION-TO-AMBIENT
125/W
125/W
130/W
135/W
150/W
NOTE6: Each layer uses one ounce copper
REV1.1
- OCT 2011 RELEASED, NOV 2014 UPDATED -
- 16 -










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