Specifications

WM_PRJ_Q2501_PTS_002 - 001
March 2004
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3.1.2 RTC Back-up supply
3.1.2.1 Design requirements
VCC_RTC pin is used to provide a back-up power supply for the internal Real
Time Clock (RTC).
The RTC is supported by the WISMO Quik Q2501 module when powered on,
but a back-up power supply is needed to save date and time information
when the module is switched off.
If the RTC is not used this pin can be left open.
Back-up Power Supply can be provided by:
 A super capacitor,
 A non rechargeable battery,
 A rechargeable battery cell.
3.1.2.2 Typical application electrical diagram
3.1.2.2.1 Super Capacitor
WISMO
Q2501
GND
Ex: EECEOEL474S
(Panasonic)
470
Ω
VCC_RTC
+
Figure 3: RTC supplied by a super capacitor
Estimated range with 0.47 Farad Gold Cap: 25 minutes min.
Note
: the Gold Capacitor maximum voltage is 2.5 V.