6.2.4 Anti-tearing (Power Loss Protection)

In the event of a power loss during a write cycle, the integrity of the device's stored data may be recovered. This function is optional, and the host may choose to activate the anti-tearing function for any write to a User zone or Configuration zone by use of the appropriate B4 System Write command. When anti-tearing is active, write commands will take longer to execute since more write cycles are required. Additionally, the data written are limited to eight bytes.

Data are written first to a buffer zone in EEPROM instead of the intended destination address in the User zone or Configuration zone, but with the same access conditions. If this write cycle is interrupted, the original data remain intact in the User zone or Configuration zone. The data are then written in the required memory location. If this second write cycle is interrupted, the device will automatically recover the data from the system buffer zone at the next power-up and write it to the intended destination address.

In Two-Wire mode, the host is required to perform ACK polling for 36 ms after each write command when anti-tearing is active. At power-up, five clock cycles are required to check the anti-tearing flags. In the event the device needs to carry out the data recovery process the host is required to perform ACK polling for 18 ms.