Ublox SARA-N210, System Integration Manual

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SARA-N2 series - System Integration Manual
UBX-17005143 - R06 System description Page 14 of 82
1.6 System function interfaces
1.6.1 Module power-on
1.6.1.1 Switch-on events
When the SARA-N2 series modules are in the not-powered mode (i.e. switched off with the VCC
module supply not applied), they can be switched on by:

Rising edge on the VCC supply input to a valid voltage value for module supply, starting from a
voltage value lower than 1.8 V, so that the module switches on applying a proper VCC supply within
the normal operating range. (See SARA-N2 series Data Sheet
[1] .)
 Alternately, the RESET_N pin can be held low during the VCC rising edge, so that the module
switches on by releasing the RESET_N pin when the VCC voltage stabilizes at its nominal value
within the normal range.
1.6.1.2 Switch-on sequence from not-powered mode
Figure 5 shows the modules power-on sequence from the not-powered mode, describing the following
phases:

The external supply is applied to the VCC module supply inputs, representing the start-up event.
 The RESET_N line rises suddenly to high logic level due to internal pull-up to VCC.
 The V_INT generic digital interfaces supply output is enabled by the integrated power
management unit.

The RXD UART data output pin also rises to the high logic level, at VCC voltage value
 A greeting message is sent on the RXD pin (for more details see SARA-N2 series AT Commands
Manual
[3] ). From now on the module is fully operational and the UART interface is functional
VCC
RESET_N
V_INT
HIGH when radio is ON
LOW when radio is OFF
RXD
System State
OFF ON
0 s ~3.5 s
Module is
operational
Start-up
event
Greeting text
Figure 5: SARA-N2 series power-on sequence from not-powered mode
☞
No voltage driven by an external application should be applied to the UART interface of the module
before applying the VCC supply, to avoid latch-up of circuits and allow a proper boot of the module.
☞
No voltage driven by an external application should be applied to any generic digital interface of
the module (GPIOs, I2C interface) before the switch-on of the generic digital interface supply
source of the module (V_INT), to avoid latch-up of circuits and allow a proper boot of the module.