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SLUS501A – OCTOBER 2001
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FEATURES
DESCRIPTION
D
D
Designed Specifically to Work With
Current-Limited Wall Supplies
The bq2420x series are simple Li-Ion linear
charge management devices targeted at low-cost
and space limited charger applications. The
bq2420x series offer integrated powerFET,
high-accuracy voltage regulation, temperature
monitoring, charge status, and charge
termination, in a single monolithic device.
Ideal for Low Dropout Charger Design for
Single-Cell Li-Ion Packs With Coke or
Graphite Anodes
D
D
Integrated PowerFET for 500 mA
Integrated Voltage Regulation With 0.5%
Accuracy
The bq2420x is designed to work with a
current-limited wall-mount transformer and
therefore does not provide any current regulation.
However, these devices offer a fixed internal
current limit to prevent damage to the internal
powerFET. A time-limited pre-conditioning phase
is provided to condition deeply discharged cells.
Once the battery reaches the charge voltage, the
high accuracy voltage regulation loop takes over
and completes the charge cycle. Charge is
terminated based on minimum current. An internal
charge timer provides a backup safety for charge
termination.
D
Battery Insertion and Removal Detection
D
Charge Termination by Minimum Current and
Time
D
D
D
Pre-Charge Conditioning With Safety Timer
Sleep Mode for Low-Power Consumption
Charge Status Output for LED or Host
Processor Interface Indicates
Charge-in-Progress, Charge Completion, and
Fault Conditions
D
D
Optional Temperature Monitoring Before and
During Charge
Other standard features include an automatic
Small, 8-Pin Power-Pad MSOP Package
sleep mode activated when V
battery voltage and a recharge feature activated
falls below the
CC
when the battery voltage falls below the V
threshold.
RCH
TYPICAL APPLICATION
bq24202DGN
DC+
In addition to the standard features, the core
product provides two additional enhancements:
temperature monitoring and status display. The
temperature-sense circuit continuously measures
battery temperature using an external thermistor
and inhibits charge until the battery temperature is
within the user–defined thresholds. The STAT pin
indicates three conditions of operation of the
charger. These conditions are charge-
in-progress, charge complete, and fault. This
output can be used to drive an LED or an interface
to a microcontroller.
1
2
3
4
IN
OUT
8
7
6
5
C1
C1
VCC BAT
+
STAT
VSS
CE
DC–
R1
N/C
BATTERY PACK
UDG–01111
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Copyright 2001, Texas Instruments Incorporated
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ꢢ ꢦ ꢣ ꢢꢛ ꢜꢯ ꢞꢝ ꢡ ꢨꢨ ꢧꢡ ꢟ ꢡ ꢠ ꢦ ꢢ ꢦ ꢟ ꢣ ꢪ
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