lp8765rlx National Semiconductor Corporation, lp8765rlx Datasheet - Page 13

• Manufacturer Part Number: lp8765rlx
• Description: High Performance Power Management Unit For Handset Applications
• Manufacturer: National Semiconductor Corporation

Linear Li-Ion Battery Charger with
Single Input
LP8765 has a built-in Li-Ion/Li-Poly battery management sys-
tem. Its main features are:
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CHARGER FUNCTION
After detecting stable voltage on input (Put 10 µF 35V rated
capacitor at input), charger enters pre-charge mode. In this
mode battery is charged with pre-charge current until battery
voltage reaches full-rate threshold. Now full charging current
EOC & BATTERY DEFAULT SETTING
By default the EOC and Battery Detection Function will be
disabled/masked off (2 EOC bits = 00) in order to support
factory testing or software downloading without the main bat-
tery. in a normal customer usage, the BB processor should
enable the EOC and Battery detection through the I
the system startup.
HIGH-CURRENT MODE
The high-current mode should be used only during factory
test, and there are few limitations since it is an add-on feature
after the LP8765 was defined.
Once the high-current mode is enabled by programming the
2 MSB of ICHARGE to 11, three charger functions will be dis-
abled:
Single input - AC adapter or USB
CC/CV linear charging
Selectable battery regulation voltage
Flexible charging cycle control
Wide array of charging current
Safety timer
2
C after
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is applied to the battery, until termination voltage is reached.
After that, charger enters constant voltage mode, where con-
stant battery voltage is maintained.
END-OF-CHARGE (EOC) FUNCTION
This function ends the charging cycle if charger has reached
constant voltage mode. It has automatic and manual control
possibilities. Automatic EOC is enabled if AUTOMATIC
START/STOP bit is set to 1, otherwise manual control is used.
Automatic EOC measures charging current and compares it
to selected EOC current level. If charging current drops below
EOC current threshold, then charging cycle is ended. It is also
possible to set EOC time delay. This is the duration for which
charging current must be below EOC level before charging
ends. For manual EOC write '1' to STOP CHARGING in reg-
ister 0x39 to stop charging, and write '1' to START CHARG-
ING in register 0x39 to start charging again. These two bits
are WRITE ONLY, and only one bit can be set to '1' at a time.
1.
2.
3.
This high-current mode is not guaranteed to operate normally
if the load is too high or with fast dynamic changes due to the
following limitations:
1.
2.
Charger current limit
Battery voltage OVP (4.9V)
Charger Thermal regulation (115°C)
There is only one bump assigned for VBATT, so the
maximum DC load is 1.5A.
The charger output will vary when load step is applied
since there is no main battery connected.
30162006
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