FEATURES

ß Two 32–bit counters keep track of real time and elapsed time

ß Counters keep track of seconds for over 125 years

ß Battery powered counter counts seconds from the time battery is attached until VBAT is less than 2.5 volts

ß VCC powered counter counts seconds while VCC is above 4.25 volts and retains the count in the absence of VCC under battery backup power

ß Clear function resets selected counter to 0

ß Read/Write serial port affords low pin count

ß Powered internally by a lithium energy cell that provides over 10 years of operation

ß 1-byte protocol defines read/write, counter address and software clear function

ß Self-contained crystal provides an accuracy of ±2 min per month

ß Operating temperature range of 0°C to 70°C

ß Low profile SIP module

DESCRIPTION

The DS1603 is a real time clock/elapsed time counter designed to count seconds when VCC power is applied and continually count seconds under battery backup power with an additional counter regardless of the condition of VCC. The continuous counter can be used to derive time of day, week, month, and year by using a software algorithm. The VCC powered counter will automatically record the amount of time that VCC power is applied. This function is particularly useful in determining the operational time of equipment in which the DS1603 is used. Alternatively, this counter can also be used under software control to record real time events. Communication to and from the DS1603 takes place via a 3–wire serial port. A 1-byte protocol selects read/ write functions, counter clear functions and oscillator trim. The device contains a 32.768 kHz crystal which will keep track of time to within ±2 min/mo. An internal lithium energy source contains enough energy to power the continuous seconds counter for over 10 years.

DS1603 ELAPSED TIME COUNTER BLOCK DIAGRAM Figure 1

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