AXP209 Datasheet, PDF (22/45 Pages) List of Unclassifed Manufacturers – Enhanced single Cell Li-Battery and Power System Management IC

AXP209
Enhanced single Cell Li-Battery and Power System Management IC
10uF
C2
NTC
GND
BAT
TS
In the diagram above, VTH/VTL refers to the high temperature threshold and low temperature
threshold, which is programmable via registers REG38H/39H/3CH/3DH respectively. VTE=0.2V. The
temperature sensitive resistor suggested is a NTC temperature-sensitive resistor, which is 10Kohm and
1% accuracy at 25℃. The AXP209 will send a constant current via TS pin, and the current can be set
as 20uA, 40uA, 60uA, and 80uA (See registerREG84H) to adapt to different NTC resistors. When the
current goes through the temperature-sensitive resistor, a voltage is generated, which will be
measured by ADC, and compared with regulated value to release corresponding IRQ or suspend the
charge.
If the resistance value of temperature-sensitive resistor is too high or too low, extra resistors can be
placed in series or parallel to expand the detect extent. If the battery does not incorporate a themistor,
the TS pin can be linked to the ground, and in that case, AXP209 will automatically disable the battery
temperature monitoring function.
Battery Detection
AXP209 will automatically detect the battery presence, record the result in registers (refer to REG01H)
and send IRQ13, IRQ14.
Battery detection can be enabled and disabled by the Host. (Refer to register REG32H.)
9.4 Backup battery
The AXP209 supports backup battery charging and discharge. When no main power(BAT/ACIN/VBUS)
is available, LDO1 will choose the backup battery to support the operation of some circuits, such as the
system real-time clock, etc.
When there is a main power, REG35H[7] can be set to charge the backup battery, whose target voltage
is 3.0V by default (adjustable via REG35H[6:5]) and charge current is 200uA by default ( adjustable via
REG35H[1:0]).
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