LP3918 Datasheet, PDF (25/39 Pages) National Semiconductor (TI) – Battery Charge Management and Regulator Unit

LP3918
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BIT
1
0
SNVS476D – AUGUST 2007 – REVISED MAY 2013
Table 15. Register Address 8h'13: CHGSTATUS1 (continued)
NAME
Fullrate
PRECHG
FUNCTION (if bit = '1')
Set when the charger is in CC/CV mode.
Set during precharge.
Charger Status Register 2 Read only
Table 16. Register Address 8h'13: CHGSTATUS2
BIT
NAME
FUNCTION (if bit = '1')
1
Tout_
Set after timeout in CV phase.
ConstV
0
BAD_
Set at bad battery state.
BATT
IMON CHARGE CURRENT MONITOR
Charge current is monitored within the charger section and a proportional voltage representation of the charge
current is presented at the IMON output pin. The output voltage relationship to the actual charge current is
represented in the following graph and by the equation:
V_IMON(mV) = (2.47 x I_CHG)(mA)
1.729
1.235
0.247
100
500
700
CHARGE CURRENT (mA)
Figure 12. IMON Voltage vs Charge Current
Note that this function is not available if there is no input at CHG_IN or if the charger is off due to the input at
CHG_IN being outwith the operating voltage range.
LDO Information
OPERATIONAL INFORMATION
The LP3918 has 7 LDO's of which 3 are enabled by default, LDO's 1,2 and 3 are powered up during the power
up sequence. LDO4, 5 and 6 are separately, externally enabled and will follow LDO2 in start up if their respective
enable pin is pulled high. LDO2, LDO3 and LDO7 can be enabled/disabled via the serial interface.
LDO2 must remain in regulation otherwise the device will power down. While LDO1 is enabled this must also be
in regulation for the device to remain powered. If LDO1 is disabled via I2C interface the device will not shut
down.
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