M41TC8025CMC7F datasheet(29/41 Pages) STMICROELECTRONICS

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M41TC8025

Operation

The VLF (Voltage Low Flag) bit indicates a low voltage occurrence. At initial power-up, the

VLF bit is set to 1 and the user needs to reset it to 0 in the startup routine. The VLF bit is

automatically set and can only be reset to 0 by the user.

During operation, if VLF=1, all the register data is not guaranteed to be correct and the RTC

needs initialization.

The VDET (Voltage Detection Flag) bit indicates the status of temperature compensation. At

initial power-up, the VDET bit is set to 1 and the user needs to reset it to 0 in the startup

routine.

During operation, if VDET=1, although the timekeeping is still functional, the temperature

compensation stops and the timing accuracy is not guaranteed. The VDET bit is

automatically set and can only be reset to 0 by the user.

VLF and VDET detection occurs during the temperature compensation period

(Section 2.4.4: Temperature compensation on page 17). The worst case delay is 30

seconds for these bits to be set to 1 (longest temperature compensation period).

2.11

Application

2.11.1

Battery backup and recovery

Figure 18 gives an example of the battery backup for the M41TC8025. The diode in the

battery block is only required when using a lithium battery. The battery backup sequence

and AC characteristics are given in Figure 19 and Table 23.

Figure 18. Battery backup connection

Obsolete

Product(s)

- Obsolete

Product(s)

M41TC8025CMC7F 数据表(PDF) 29 Page - STMicroelectronics