User Manual
LARA-R2 series - System Integration Manual
UBX-16010573 - R02 Objective Specification System description
Page 27 of 148
1.6 System function interfaces
1.6.1 Module power-on
When the LARA-R2 series modules are in the not-powered mode (switched off, i.e. the VCC module supply is
not applied), they can be switched on as following:
Rising edge on the VCC input pins to a valid voltage for module supply: the modules switch on if the VCC
supply is applied with a rise time of less than 10 ms from 2.1 V to 3.0 V, reaching a proper nominal voltage
value within the VCC operating range.
Alternately, in case for example the fast rise time on VCC rising edge cannot be guaranteed by the application,
LARA-R2 series modules can be switched on from not-powered mode as following:
RESET_N input pin is held low by the external application during the VCC rising edge, so that the modules
will switch on when the external application releases the RESET_N input pin from the low logic level after
that the VCC supply voltage stabilizes at its proper nominal value within the operating range
PWR_ON input pin is held low by the external application during the VCC rising edge, so that the modules
will switch on when the external application releases the PWR_ON input pin from the low logic level after
that the VCC supply voltage stabilizes at its proper nominal value within the operating range
When the LARA-R2 series modules are in the power-off mode (i.e. switched off with valid VCC module supply
applied), they can be switched on as following:
Low pulse on the PWR_ON pin, which is normally set high by an internal pull-up, for a valid time period: the
modules start the internal power-on sequence when the external application releases the PWR_ON pin from
the low logic level after that it has been set low for an appropriate time period
Rising edge on the RESET_N pin, i.e. releasing the pin from the low level, as that the pin is normally set high
by an internal pull-up: the modules start the internal power-on sequence when the external application
releases the RESET_N pin from the low logic level
RTC alarm, i.e. pre-programmed alarm by AT+CALA command (see u-blox AT Commands Manual [2]).
As described in Figure 12, the LARA-R2 series PWR_ON input is equipped with an internal active pull-up resistor
to the V_BCKP supply: the PWR_ON input voltage thresholds are different from the other generic digital
interfaces. Detailed electrical characteristics are described in LARA-R2 series Data Sheet [1].
Baseband
Processor
15
PWR_ON
LARA-R2 series
2
V_BCKP
Power-on
Power
Management
Power-on
10k
Figure 12: LARA-R2 series PWR_ON input description