u-blox LEON-G100 ECALL, System Integration Manual

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LEON-G100 / LEON-G200 - System Integration Manual
GSM.G1-HW-09002-G3 Preliminary System description
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LEON-G100 /
LEON-G200
C1
(a)
2 V_BCKP
R2
C2
(superCap)
(b)
2 V_BCKP
2V
(c)
2 V_BCKP
LEON-G100 /
LEON-G200
LEON-G100 /
LEON-G200
Figure 17: Real time clock supply (V_BCKP) application circuits: (a) using a 100 µF capacitor to let the RTC run for 50 seconds at
25°C; (b) using a 70 mF capacitor to let the RTC run for ~10 hours at 25°C when the VCC supply is removed; (c) using a not
rechargeable battery
Reference Description Part Number - Manufacturer
C1 100 µF Tantalum Capacitor GRM43SR60J107M - Murata
R2 4.7 k Ω Resistor 0402 5% 0.1 W RC0402JR-074K7L - Yageo Phycomp
C2 70 mF Capacitor XH414H-IV01E - Seiko Instruments
Table 10: Example of components for V_BCKP buffering
If longer buffering time is required to allow the time reference to run during a disconnection of the
VCC supply,
a rechargeable battery, which has to be able to provide a 2.0 V nominal voltage and must not exceed the
maximum operating voltage value of 2.25 V, can be connected to the
V_BCKP pin with a proper series resistor.
Otherwise a not rechargeable battery, which has to be able to provide a 2.0 V nominal voltage and must not
exceed the maximum operating voltage value of 2.25 V, can be connected to the
V_BCKP
pin with a proper
series resistor and a proper series diode. The purpose of the series resistor is to limit the battery charging current
due to the battery specifications, and also to let a fast rise time of the voltage value at the
V_BCKP pin after
VCC
supply has been provided. The purpose of the series diode is to avoid a current flow from the
V_BCKP
pin
of the module to the not rechargeable battery.
1.6 System functions
1.6.1 Module power on

The power-on sequence of the module is initiated in one of 4 ways:

Rising edge on the VCC pin to a valid voltage as module supply

Low level on the PWR_ON signal

RTC alarm

Charger detection on the V_CHARGE and CHARGE_SENSE pins (LEON-G200 only)
Name Description Remarks
PWR_ON Power-on input PWR_ON pin has high input impedance.
Do not keep floating in noisy environment: external pull-up
required.
Table 11: Power-on pin
PWR_ON pin ESD sensitivity rating is 1 kV (HBM JESD22-A114F). A higher protection level could be
required if the line is externally accessible on the application board. A higher protection level can be
achieved mounting an ESD protection (e.g. EPCOS CA05P4S14THSG varistor array) on the line
connected to this pin if it is externally accessible on the application board.