Wavecom WISMO Quik Q2406 - Typical Implementation; Figure 22: RTC Supplied by a Capacitor; Figure 23: RTC Supplied by a Super Capacitor

WM_PRJ_Q2400_PTS_005 -007
18th January 2006
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2.10.2 Typical implementation
2.10.2.1 Capacitor
VCC
_
RTC
Regulator
2.5 V
±
10%
(With very Low Iq)
+VBATT
470
1K
Ex: 470uF
Shottky
Diode
En
Vout
Gnd
Vin
Figure 22: RTC Supplied by a capacitor
Estimated range with 470 µF Capacitor: ~30 seconds.
2.10.2.2 Super Capacitor
Regulator
2.5 V ±10%
(With very Low Iq)
+
VBATT
470 1K
Ex: EECE0EL474S
(Panasonic)
Shottky
Diode
En
Vout
Gnd
Vin
VCC
_
RTC
Figure 23: RTC supplied by a super capacitor
Estimated range with 0.47 Farad Gold Capacitor: 2 hours min.
Note: the Gold Capacitor maximum voltage is 2.5 V.