Datasheet

Applications information: charging process L6924U
22/37 Doc ID 14716 Rev 2
Figure 15. T
PRG
pin connection
Where,
R
PRG
= resistor which sets the current (R
USB
or R
AC
)
V
REF
= 1.8 V,
K
T
= 279 x 10
5
,
V
BG
= 1.23 V, and
T
MAXCH
is the charging time given in seconds.
If the battery does not reach the end-of-charge condition before the timer expires, a fault is
issued.
Also during the pre-charge phase there is a safety timer, given by:
Equation 11
If this timer expires and the battery voltage is still lower than V
PRETH
, a fault signal is
generated, and the charge process finishes.
Note: When the device is charged in low power USB mode, in order to take into account the
reduced charge current, the maximum charging time is proportionally increased (five times
the maximum charging time calculated with R
USB
).
MAXCHMAXPRECH
TT ×=
8
1