Specifications

XT65/XT75 Hardware Interface Description
3.3 Power-Up / Power-Down Scenarios
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XT65_XT75_HD_v01.001 Page 37 of 133 2007-1-8
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While XT65/XT75 is in Power-down mode the application interface is switched off and must not be fed from any
other source. Therefore, your application must be designed to avoid any current flow into any digital pins of the
application interface, especially of the serial interface. No special care is required for the USB interface which is
protected from reverse current.
Figure 8: Signal states during turn-off procedure
Note 1: Depending on capacitance load from host application
3.3.3.2 Leakage Current in Power-Down Mode
The leakage current in Power-down mode varies: If the supply voltage at BATT+ was disconnected and then
applied again without starting up the XT65/XT75 module, the leakage current is undeterminately higher than if
the XT65/XT75 module was started and then powered down again.
In order to minimize leakage current the following steps should therefore be completed after initially applying
BATT+:
• Power up the module (see Section 3.3).
• Power up the module’s GPS receiver either in Transparent mode (AT^SGPSS=1,1) or in AT mode
(AT^SGPSS=1,0). For more information on how to use the command AT^SGPSS and on how to control the
GPS receiver see [1] and [12].
• Wait at least 1 second.
• Turn the module’s GPS receiver off again by using AT^SGPSS=0.
• Switch the module off by using AT^SMSO.