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AC75 Hardware Interface Description
Strictly confidential / Preliminary
3.5
Charging Control
AC75 integrates a charging management for rechargeable Lithium Ion and Lithium Polymer
batteries. You can skip this chapter if charging is not your concern, or if you are not using the
implemented charging algorithm.
The following sections contain an overview of charging and battery specifications. Please
refer to [4] for greater detail, especially regarding requirements for batteries and chargers,
appropriate charging circuits, recommended batteries and an analysis of operational issues
typical of battery powered GSM/GPRS applications.
3.5.1 Hardware Requirements
AC75 has no on-board charging circuit. To benefit from the implemented charging
management you are required to install a charging circuit within your application according to
the Figure 46.
3.5.2 Software Requirements
Use the command AT^SBC, parameter <current>, to enter the current consumption of the
host application. This information enables the AC75 module to correctly determine the end of
charging and terminate charging automatically when the battery is fully charged. If the
<current> value is inaccurate and the application draws a current higher than the final charge
current, either charging will not be terminated or the battery fails to reach its maximum
voltage. Therefore, the termination condition is defined as: final charge current (50mA) plus
current consumption of the external application. If used the current flowing over the VEXT pin
of the application interface (typically 2.9V) must be added, too.
The parameter <current> is volatile, meaning that the factory default (0mA) is restored each
time the module is powered down or reset. Therefore, for better control of charging, it is
recommended to enter the value every time the module is started.
See [1] for details on AT^SBC.
AC75_HD_V00.202
Page 41 of 120
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27.04.2006
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