Datasheet

Applications information: charging process L6924D
20/38 Doc ID 11908 Rev 9
7.6 Recharge flow chart
Figure 15. Recharge flow chart
7.7 Recharge threshold
When, from an end-of-charge condition, the battery voltage goes lower than the recharging
threshold (V
RCH
), the device goes back in charging state. The value of the recharge
threshold is V
OPRG
–150 mV.
7.8 Maximum charging time
To avoid the charging of a dead battery for a long time, the L6924D has the possibility to set
a maximum charging time starting from the beginning of the fast-charge phase. This timer
can be set with a capacitor, connected between the T
PRG
pin and GND. The C
TPRG
is the
external capacitor (in nF) and is given by the following equation:
Equation 11
Note: The maximum recommended C
TPRG
value must be less than 50 nF.
END of CHARGE
V
BAT
>
V
RCH
Detect Low
V
BAT
>
V
PRETH
FAST CHARGE
Detect High
V
BAT
>
V
RCH
BATTERY
ABSENT
PRE CHARGE
FAULT
IND FAULT
V
BAT
>
V
RCH
Detect High Fault
V
BAT
<
V
ABS
Detect Low Fault
V
BAT
>
V
PRETH
BATTERY
ABSENT
YES
NO
NO
NO
YES
YES
NO
YES
NO
NO
YES
YES
DETECT LOW = a I
SINK
is sunk for a T
DET
from the battery
DETECT HIGH = a I
INJ
is injected for a T
DET
in the battery
DETECT LOW FAULT = a I
SINK
is sunk for a T
DET
from the battery
DETECT HIGH FAULT = a I
INJ
is injected for a T
DET
in the battery
V
ABS
= V
OPRG
– 50mV
V
RCH
= V
OPRG
– 150mV
T
DET
= 100ms (Typ.)
I
SINK
= I
INJ
= 1mA (Typ.)
RETURN TO CHARGING PROCESS
FLOW CHART
GO TO BATTERY ABSENT
FLOW CHART
FROM CHARGING PROCESS FLOW CHART
9
10×
⎟
⎟
⎟
⎟
⎠
⎞
⎜
⎜
⎜
⎜
⎝
⎛
×
=
REF
PRG
BG
T
MAXCH
TPRG
V
R
V
K
T
C