User's Manual

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Note d’étude / Technical document : URD1– OTL
5665.3 – 003 / 72238 Edition 01
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• To avoid any current re-injection on VPERM (3.0V)
 The POK_IN signal is internally pulled up and can be connected to an open drain transistor.
• To avoid any current re-injection on VRTC (3.0V)
 The VBACKUP signal has to be only connected to a DC coin 3V battery or a capacitor of 10µF.
• To avoid any current re-injection on VSIM (1.8V or 2.9V)
 Use only VSIM pads to supply the sim card or sim chip.
• To avoid any current re-injection on VBAT (3.2V to 4.5V)
 Use a VBAT signal with a fast rise time to have a VBAT final value as fast as possible. (see hereafter)
 In case of needs, use 2 serial capacitors of 10µF to connect the audio speaker lines to the external system
inputs.
4.14.6 CASE OF VBAT RISE TIME
The VBAT rise time from 0V to its final value has to be lower than 1ms
(1)
. This is necessary in order to avoid any
possible failure during the power up. If this value cannot be guaranteed, then some MOS transistors could be
used to create a fast rise time switch able to quickly commute from the VBAT final value to the modules power
pads.
(1)
This value will be updated to a higher final value including the worst case.
4.14.7 START- UP
To start the module, first power up VBAT, which must be in the range 3.2V ~ 4.5V, and able to provide 2.2A
during the TX bursts
(Refer to the module specification for more details).

POK_IN is a low level active signal internally pulled up to a dedicated power domain to 3V.
As POK_IN is internally pulled up, a simple open collector or open drain transistor can be used for ignition.

To start the module, a low level pulse must be applied on POK_IN during 2000 ms.

RESET must not be Low during that period of time
After a few seconds, the CTS goes to the active state when the module is ready to receive AT commands.

VGPIO is a supply output from the module that can be used to check if the module is alive.
• When VGPIO = 0V the module is OFF
• When VGPIO = 2.8V the module is ON (It can be in Idle, communication or sleep modes)