User's Manual

WM_PRJ_Q2400_PTS_002 - 004
March 5, 2004
2.14 Battery charging interface
2.14.1 Hardware description
The WISMO module supports one battery charging circuit for Li-Ion batteries.
This circuit uses an interface which consists of a current source inputs (CHG_IN) where the constant
current has to flow in order to charge the battery.
This current value depends on the battery capacity. It is recommended to provide a current equal to
the value of the capacity plus 50 mA. For a 550 mA battery the current will be 600 mA. The
maximum current is 800 mA.
A specific AT command (AT+WBCM), available from 4.3 level, allows to manage the battery charge
(start and stop the charge, enable or disable unsolicited Battery Charge Indications and set the
battery charge parameters).
The WISMO module monitors the battery voltage to detect the end of the charge.
The WISMO module also monitors the temperature of the battery through the BAT_TEMP pin which
has to be connected to a temperature sensor inside the battery (a NTC resistor for instance).
Pin description
Signal Pin number I/O I/O type Description
CHG_IN 1, 2, 4 I Supply Current source input
BAT_TEMP 38 I Analog A/D converter
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