How is the rechareable coin cell protected against deep discharge if the coin cell is connected to Pin 42 and the PMIC is in COIN CELL MODE? Is an integrated undervoltage protection in the MMPF0100A available? If yes, at which coin cell voltage is the shut off Level? And what about the leakage current after shut off? If no what is the recommended external additional circuit to protect the coin cell for destructive deep discharge?