Specifications

XT65/XT75 Hardware Interface Description
3.3 Power-Up / Power-Down Scenarios
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XT65_XT75_HD_v01.001 Page 39 of 133 2007-1-8
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The maximum temperature ratings are stated in Section 7.2. Refer to Table 7 for the associated URCs.
3.3.4.2 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).
3.3.4.3 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 suffi-
cient 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 shut-
down 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.
This type of URC does not need to be activated by the user. It will be output automatically when fault conditions
occur.
Table 7: Temperature dependent behavior
Sending temperature alert (15s after XT65/XT75 start-up, otherwise only if URC presentation enabled)
^SCTM_A: 1 Caution: Battery close to overtemperature limit.
^SCTM_B: 1 Caution: Bboard close to overtemperature limit.
^SCTM_A: -1 Caution: Battery close to undertemperature limit.
^SCTM_B: -1 Caution: 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: Battery equal or beyond overtemperature limit. XT65/XT75 switches off.
^SCTM_B: 2 Alert: Board equal or beyond overtemperature limit. XT65/XT75 switches off.
^SCTM_A: -2 Alert: Battery equal or below undertemperature limit. XT65/XT75 switches off.
^SCTM_B: -2 Alert: Board equal or below undertemperature limit. XT65/XT75 switches off.