L6924U STMicroelectronics, L6924U Datasheet - Page 27

• Manufacturer Part Number: L6924U
• Description: Battery Management USB Battery Charger System w/integra
• Manufacturer: STMicroelectronics

Specifications of L6924U

• Product: Charge Management
• Battery Type: Li-Ion
• Output Voltage: 4.2 V
• Output Current: 30 mA
• Maximum Operating Temperature: + 125 C
• Minimum Operating Temperature: - 40 C
• Package / Case: VFQFPN
• Mounting Style: SMD/SMT
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

L6924U
8.2
8.3
Battery absence detection
This feature provides a battery absent detection scheme to detect the removal or the
insertion of the battery. If the battery is removed, the charge current falls below the I
At the end of the de-glitch time, a detection current I
output for a time of T
V
checked to see if the voltage on the output goes higher than V
voltage changes from V
battery is connected to the charger. The T
Equation 24
Figure 20. Battery absence detection flow chart
Status pins
To indicate various charger status conditions, there are two open-collector output pins, ST1
and ST2. These status pins can be used either to drive status LEDs, connected with an
external power source, by a resistor, or to communicate to a host processor.
PRETH
YES
, a current equal to I
Detect High Absent
Detect Low Absent
BATTERY
ABSENT
V
V
V
V
PRETH
>
>
BAT
BAT
RCH
NO
DETECT
NO
YES
PRETH
DETECT
. The device checks the voltage at the output. If it is below the
Doc ID 14716 Rev 2
to V
DETECT LOW ABSENT = a I
DETECT HIGH ABSENT = a I
T
I
SINK
DET
RCH
= I
PRE CHARGE
is injected in the output capacitor for a T
= 100ms (Typ.)
T
Application information: monitoring and protection
INJ
DETECT
and vice versa in a T
= 1mA (Typ.)
FAST CHARGE
DETECT
=
54×
T
MAXCH
is expressed by:
10
DETECT
3
SINK
INJ
is injected for a T
, equal to 1 mA, is sunk from the
is sunk for a T
DETECT
RCH
(4.05 V). If the battery
time, it means that no
DET
DET
from the battery
in the battery
DETECT
, and it is
ENDTH
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