u-blox TOBY-L4 Series System Integration Manual

Contents

TOBY-L4 series - System Integration ManualUBX-16024839 - R04 System descriptionPage 34 of 143Figure 14 describes the TOBY-L4 series modules’ switch-off sequence started by means of the PWR_ON inputpin, allowing storage of current parameter settings in the module’s non-volatile memory and a clean networkdetach, with the following phases A low pulse with the appropriate time duration is applied at the PWR_ON input pin, which is normally sethigh by an internal pull-up: the module starts the switch-off routine when the PWR_ON signal is releasedfrom the low logical level. At the end of the switch-off routine, all the digital pins are tri-stated and all the internal voltage regulatorsare turned off, including the generic digital interfaces supply (V_INT). Then, the module remains in power-off mode as long as a switch-on event does not occur (i.e. applying asuitable low level pulse to the PWR_ON input pin), and enters not-powered mode if the supply is removedfrom the VCC pins.VCCPWR_ONRESET_NV_INTInternal ResetSystem StateBB Pads StateOFFTristate / FloatingONOperational -> TristateOperational0 s ~2.5 s ~5 sThe module startsthe switch-off routineVCCcan be removedFigure 14: TOBY-L4 series power-off sequence descriptionThe Internal Reset signal is not available on a module pin, but the application can monitor the V_INT pinto sense the end of the power-off sequence.The VCC supply can be removed only after the end of the module internal switch-off routine, i.e. onlyafter that the V_INT voltage level has gone low.The duration of each phase in the TOBY-L4 series modules’ switch-off routines can largely vary dependingon the application / network settings and the concurrent module activities.