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SIM548C Hardware Design
SIM548C_HD_V1.01
09.05.2008
42
Figure
12
: RTC supply from rechargeable battery
Figure
13
: RTC supply from capacitor
z
Li-battery backup
Rechargeable Lithium coin cells such as the TC614 from Maxell, or the TS621 from Seiko, are
also small in size, but have higher capacity than the double layer capacitors resulting in longer
backup times.
Typical charge curves for each cell type are shown in following figures. Note that the rechargeable
Lithium type coin cells generally come pre-charged from the vendor.