LP3921 Datasheet, PDF (19/41 Pages) National Semiconductor (TI) – Battery Charger Management and Regulator Unit with Integrated Boomer® Audio Amplifier

LP3921
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VTERM[1]
0
0
1
1
SNVS580A – AUGUST 2008 – REVISED MAY 2013
Table 6. Charging Termination Voltage Control
VTERM[0]
0
1
0
1
Termination Voltage (V)
4.1
4.2 (Default)
4.3
4.4
Table 7. End Of Charge Current Control⁽¹⁾
PROG_EOC[1]
0
0
1
1
PROG_EOC[0]
0
1
0
1
End of Charge Current
0.1 (Default)
0.15C
0.2C
0.25C
(1) Note: C is the set charge current.
PROG_VRSTRT[1]
0
0
1
1
Table 8. Charging Restart Voltage Programming
PROG_VRSTRT[1]
0
1
0
1
Restart Voltage(V)
V_TERM - 50 mV
V_TERM - 100 mV
V_TERM - 150 mV
V_TERM - 200 mV
USB_Mode_En
0
1
0
1
CHG_Mode_En
0
0
1
1
Table 9. USB Charging Selection
Mode
Fast Charge
Fast Charge
USB
USB
Current
Default or Selection
Default or Selection
100 mA
450 mA
Battery Charge Management
A charge management system allowing the safe charge and maintenance of a Li-Ion battery is implemented on
the LP3921. This has a CC/CV linear charge capability with programmable battery regulation voltage and end of
charge current threshold. The charge current in the constant current mode is programmable and a maintenance
mode monitors for battery voltage drop to restart charging at a preset level. A USB charging mode is also
available with 2 charge current levels.
CHARGER FUNCTION
Following the correct detection of an input voltage at the charger pin the charger enters a pre-charge mode. In
this mode a constant current of 50 mA is available to charge the battery to 3.0V. At this voltage level the charge
management applies the default (100 mA) full rate constant current to raise the battery voltage to the termination
voltage level (default 4.2V). The full rate charge current may be programmed to a different level at this stage.
When termination voltage (V_TERM) is reached, the charger is in constant voltage mode and a constant voltage of
4.2V is maintained. This mode is complete when the end of charge current (default 0.1C) is detected and the
charge management enters the maintenance mode. In maintenance mode the battery voltage is monitored for
the restart level (4.05V at the default settings) and the charge cycle is re-initiated to re-establish the termination
voltage level. For start up the EOC function is disabled. This function should be enabled once start up is
complete and a battery has been detected. EOC is enabled via register CHGCNTL1, Table 10.
The full rate constant current rate of charge may be programmed to 19 levels from 50 mA to 950 mA. These
values are given in Table 5 and Table 13.
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