DS1689SSLASHT datasheet(23/36 Pages) DALLAS

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DS1689/DS1693

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ELAPSED TIME COUNTERS

The DS1689/DS1693 has two 32-bit elapsed time counters, which reside in bank 1 of the RTC registers.

To access these counters the DV0 bit in register A must first be set to a logical 1.

The VCC powered elapsed time counter resides in register 54H through 57H. The LSB of this counter

resides in register 54 and the MSB is in 57H. The VCC powered elapsed time counter runs only while the

VCCI input is within nominal limits. The elapsed time counter is a binary counter that records the number

of seconds that have elapsed. The counter can be read or written at the user’s discretion. The VBAT-

powered elapsed time counter resides in register 58H through 5BH. The LSB of this counter resides in

The VBAT powered elapsed time counter runs continually as long as the VBAT or VBAUX pin is within

nominal limits regardless of the condition of VCCI. The number of seconds that have elapsed is recorded

in a binary counter and the counter can be read or written at the user’s discretion.

In a typical application, the VBAT-powered elapsed time counter can be used to record the length of time

that has elapsed from which the equipment that contains the device was first put into service. The VCC

powered counter can then be used to record the length of time that VCC power is applied. These functions

can be particularly useful for warranty and maintenance information. In addition, battery life can be

predicted based on known loading factors. However, it is worth noting that a properly selected battery

should power the DS1689/DS1693 and external RAM for the useful life of most equipment.

POWER-CYCLE COUNTER

The DS1689/DS1693 has a 16-bit power-cycle counter that resides in register 5C and 5D of bank 1. The

LSB of this counter resides in 5C and the MSB is in 5D. This binary counter is incremented by one count

each time VCCI power is applied within nominal limits. This counter can be read or written at the user’s

discretion.

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