SIM802 Hardware Design
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 are generally pre-charged from the vendor.
Figure 16: Panasonic EECEMOE204A Charge Characteristic
Figure 17: Maxell TC614 Charge Characteristic
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