TC65 Hardware Interface Description
Strictly confidential / Draft
s
TC65_HD_V00.521
Page 33 of 99
24.05.2005
Table 2: Temperature dependent behavior
Sending temperature alert (15s after TC65 start-up, otherwise only if URC presentation enabled)
^SCTM_A: 1
Caution: T
amb
of battery close to overtemperature limit.
^SCTM_B: 1
Caution: T
amb
of board close to overtemperature limit.
^SCTM_A: -1
Caution: T
amb
of battery close to undertemperature limit.
^SCTM_B: -1
Caution: T
amb
of board close to undertemperature limit.
^SCTM_A: 0
Battery back to uncritical temperature range.
^SCTM_B: 0
Board back to uncritical temperature range.
Automatic shutdown (URC appears no matter whether or not presentation was enabled)
^SCTM_A: 2
Alert: T
amb
of battery equal or beyond overtemperature limit. TC65 switches off.
^SCTM_B: 2
Alert: T
amb
of board equal or beyond overtemperature limit. TC65 switches off.
^SCTM_A: -2
Alert: T
amb
of battery equal or below undertemperature limit. TC65 switches off.
^SCTM_B: -2
Alert: T
amb
of board equal or below undertemperature limit. TC65 switches off.
3.3.3.2
Temperature Control during Emergency call
If the temperature limit is exceeded while an emergency call is in progress the engine
continues to measure the temperature, but deactivates the shutdown functionality. If the
temperature is still out of range when the call ends, the module switches off immediately
(without another alert message).
3.3.3.3
Undervoltage Shutdown if Battery NTC is Present
In applications where the module’s charging technique is used and an NTC is connected to
the BATT_TEMP terminal, the software constantly monitors the applied voltage. If the
measured battery voltage is no more sufficient to set up a call the following URC will be
presented:
^SBC: Undervoltage.
The message will be reported, for example, when you attempt to make a call while the
voltage is close to the shutdown threshold of 3.2V and further power loss is caused during
the transmit burst. In IDLE mode, the shutdown threshold is the sum of the module’s
minimum supply voltage (3.2V) and the value of the maximum voltage drop resulting from
earlier calls. This means that in IDLE mode the actual shutdown threshold may be higher
than 3.2V. Therefore, to properly calculate the actual shutdown threshold application
manufacturers are advised to measure the maximum voltage drops that may occur during
transmit bursts.
To remind you that the battery needs to be charged soon, the URC appears several times
before the module switches off.
To enable or disable the URC use the AT^SBC command. The URC will be enabled when
you enter the write command and specify the current consumption of your host application.
Step by step instructions are provided in [1].
