CHARGE CURRENT (mA)

700

100

0.247

1.235

1.729

500

LP3921

SNVS580A – AUGUST 2008 – REVISED MAY 2013

www.ti.com

Table 15. Register Address 8h'13: CHGSTATUS1 (continued)

BIT

NAME

FUNCTION (if bit = '1')

0

PRECHG

Set during precharge.

Charger Status Register 2 Read only

Table 16. Register Address 8h'13: CHGSTATUS2

BIT

NAME

FUNCTION (if bit = '1')

1

Tout_ConstV

Set after timeout in CV phase.

0

BAD_BATT

Set at bad battery state.

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:

VIMON(mV) = (2.47 x ICHG)(mA)

Figure 8. 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 less than the compliance voltage.

LDO Information

OPERATIONAL INFORMATION

The LP3921 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. LDO's 4, 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.

INPUT VOLTAGES

There are two input voltage pins used to power the 7 LDO's on the LP3921. VIN2is the supply for LDO3, LDO4,

LDO5, LDO6 and LDO7. VIN1is the supply for LDO1 and LDO2.

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