STBC03 Datasheet, PDF (25/34 Pages) STMicroelectronics – Li-Ion linear battery charger with LDO and load switches

STBC03
Operation description
By contrast, as soon as the battery voltage reaches the VPRE threshold, the constant-
current fast charge phase starts operating, and the relevant charging current increases to
the IFAST level.
Likewise, if the constant current fast charge phase is not completed within tFAST, meaning
that VBAT < VFLOAT, the charging process is stopped and a fault is signaled (CHG starts
toggling at 10.2 Hz as long as a valid VIN is present).
Should the battery voltage decrease below VPRE during the fast charge phase, the charging
process is halted and a fault is signaled. The constant-current fast charge phase lasts until
the battery voltage is lower than VFLOAT. After that, the charging algorithm switches to a
constant-voltage (CV) mode.
During the CV mode, the battery voltage is regulated to VFLOAT and the charging current
starts decreasing over time. As soon as it goes below IEND, the charging process is
considered to be completed (EOC, end-of-charge ) and the relevant status is signaled via a
4.1 Hz toggling signal on the CHG pin, again as long as a there is a valid input source
applied (VUVLO < VIN < VINOVP).
Both IPRE and the IFAST values can be programmed from 1 mA to 450 mA via an external
resistor, as described in the ISET pin description.
For any IFAST programmed value above 20 mA, the IEND value can be set either 5% or 2.5%
of the IFAST level.
For any IFAST programmed value below 20 mA, the relevant IEND value is set as per the
following table:
IFAST
Table 10: IFAST and IEND
IEND
20 mA
1.7 mA
10 mA
1.1 mA
5 mA
0.65 mA
2 mA
0.4 mA
1 mA
0.2 mA
The battery temperature is monitored throughout the charging cycle for safety reasons.
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