Charger Requirements; Table 8: At Commands Available In Charge-Only Mode - Siemens MC45 Manual

MC45 Hardware Interface Description
P R E L I M I N A R Y
Features of Charge-only mode
Once the GSM engine enters the Charge-only mode, the AT command interface presents an
Unsolicited Result Code (URC) which reads:
^SYSSTART CHARGE-ONLY MODE
Note that this URC will not appear when autobauding was activated (due to the missing
synchronization between DTE and DCE upon start-up). Therefore, it is recommended to
select a fixed baudrate before using the Charge-only mode.
While the Charge-only mode is in progress, you can only use the AT commands listed in
Table 8. For further instructions refer to the AT Command Set supplied with your GSM
engine.

Table 8: AT commands available in Charge-only mode

AT command Use
AT+CALA Set alarm time
AT+CCLK Set date and time of RTC
AT^SBC Monitor charging process
Note: While charging is in progress, no battery capacity value is available. To query
the battery capacity disconnect the charger.
If the charger connects externally to the host device no charging parameters are
transferred to the module. In this case, the command cannot be used.
AT^SCTM Query temperature range, enable/disable URCs to report critical temperature ranges
AT^SMSO Power down GSM engine
To proceed from Charge-only mode to normal operation, it is necessary to drive the ignition
line to ground. This must be implemented in your host application as described in Chapter
3.3.1.1. When the engine is in Alarm mode there is no direct way to start charging, i.e.
charging will not begin even though the charger connects to the POWER pin of MC45. See
also Chapter 3.3.5 which summarizes the various options of changing the mode of
operation.
If your host application uses the SYNC pin to control a status LED as described in Chapter
3.8.2.2, please note that the LED is off while the GSM engine is in Charge-only mode.

3.2.3.5 Charger requirements

If you are using the implemented charging technique and the charging circuit recommended
in Figure 3, the charger must be designed to meet the following requirements:
a) Simple transformer power plug
- Output voltage: 5.5V...8V (under load)
The charge current must be limited to 500mA
-
- Voltage spikes that may occur while you connect or disconnect the charger must be
limited to a maximum of 25V and must not exceed 1ms
- There must not be any capacitor on the secondary side of the power plug (avoidance of
current spikes at the beginning of charging)
b) Supplementary requirements for a) to ensure a regulated power supply
- When current is switched off a voltage peak of 10V is allowed for a maximum 1ms
- When current is switched on a spike of 1.6A for 1ms is allowed
MC45_HD_01_V00.02a Page 32 of 90 12.08.2002