User's Manual
Table Of Contents
- Contents
- Figures
- Tables
- Document history
- Introduction
- Product concept
- GSM application interface
- GSM/GPRS operating modes
- Power supply
- Power up / down scenarios
- Automatic GPRS Multislot Class change
- Charging control of the GSM part
- Power saving
- Summary of state transitions (except SLEEP mode)
- RTC backup for GSM part of XT55/56
- Serial interfaces of the XT55/56 GSM part
- Audio interfaces
- SIM interface
- Control signals
- GPS application interface
- GSM and GPS antenna interfaces
- Electrical, reliability and radio characteristics
- Mechanics
- Reference approval
- Example applications
- List of parts and accessories
XT55/56 Hardware Interface Description
Confidential / Released
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XT55/56_hd_v02.06a Page 39 of 125 17.12.2004
3.3.3.4 Undervoltage shutdown if no battery NTC is present
The undervoltage protection is also effective in applications, where no NTC connects to the
GSM_BATT_TEMP terminal. Thus, you can take advantage of this feature even though the
application handles the charging process or XT55/56 is fed by a fixed supply voltage. All you
need to do is executing the write command AT^SBC=<current> which automatically enables
the presentation of URCs. You do not need to specify <current>.
Whenever the supply voltage falls below the specified value (see Table 28) the URC
^SBC: Undervoltage
appears several times before the module switches off.
3.3.3.5 Overvoltage shutdown
For overvoltage conditions, no software controlled shutdown is implemented. If the supply
voltage exceeds the maximum value specified in Table 28, loss of data and even
unrecoverable hardware damage can occur.
Keep in mind that several XT55/56 components are directly linked to GSM_BATT+ and,
therefore, the supply voltage remains applied at major parts of XT55/56. Especially the
power amplifier is very sensitive to high voltage and might even be destroyed.