LP3910 Datasheet, PDF (32/72 Pages) Texas Instruments – Power Management IC for Hard-Drive-Based Portable Media Players

LP3910
SNVS481M – NOVEMBER 2006 – REVISED DECEMBER 2015
Feature Description (continued)
Adapter
VDD
USB
CHG_DET
USBPWR
Q1
Q2
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VBATT
Li-Ion Cell
Figure 54. Switches for USB Charging Path
8.3.4.2 Charge Status Indication
Two LEDs connected to the LP3910 are used to indicate the status of the charging. The CHG pin is connected to
a red LED that is enabled when an external power source is connected and the battery is charging. The second
STAT pin is connected to a green LED. When the battery charging transitions from CC to CV mode, then the
green LED is blinking with a 50% duty cycle and a period of 1 second. When the battery is fully charged, then the
green LED is always on.
Both LEDs are off when there is no external power connected.
Table 5. Truth Table for the LED Status Indicators
CONDITION
No Charger or USB
Charger off
Pre-Qualification
Constant Current CC
Constant Voltage CV
EOC / Top-OFF charging
Charge cycle complete
ERROR (Battery Temperature, Thermal shutdown)
Safety Timer Expired
RED LED
OFF
ON
ON
ON
ON
ON
ON
50% duty cycle
50% duty cycle
GREEN LED
OFF
OFF
OFF
OFF
50% duty cycle
ON
ON
OFF
OFF
50% duty cycle indicates the LED is pulsed on and off for equal times at a frequency of 1 Hz.
The RED pin and GREEN pin are connected to a regulated driver to ensure that the brightness is independent
from the external power. The LEDs need to be connected between the CHG and STAT pins and GND.
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