DS1603 Datasheet, PDF (1/8 Pages) National Semiconductor (TI) – TRI-STATE Dual Receiver

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DS1603
Elapsed Time Counter Module
FEATURES
§ Two 32–bit counters keep track of real time
and elapsed time
§ Counters keep track of seconds for over 125
years
§ Battery powered counter counts seconds from
the time battery is attached until V_BAT is less
than 2.5 volts
§ V_CC powered counter counts seconds while
V_CC is above 4.25 volts and retains the count
in the absence of V_CC under battery backup
power
§ Clear function resets selected counter to 0
§ Read/Write serial port affords low pin count
§ Powered internally by a lithium energy cell
that provides over 10 years of operation
§ 1-byte protocol defines read/write, counter
address and software clear function
§ Self-contained crystal provides an accuracy of
±2 min per month
§ Operating temperature range of 0°C to 70°C
§ Low profile SIP module
PIN ASSIGNMENT
V_CC
1
RST
2
DQ
3
NC
4
CLK
5
OSC
6
GND
7
PIN DESCRIPTION
RST
CLK
DQ
GND
V_CC
OSC
NC
- Reset
- Clock
- Data Input/Output
- Ground
- +5 Volts
- 1 Hz Oscillator Output
- No Connect
DESCRIPTION
The DS1603 is a real time clock/elapsed time counter designed to count seconds when V_CC power is
applied and continually count seconds under battery backup power with an additional counter regardless
of the condition of V_CC. The continuous counter can be used to derive time of day, week, month, and year
by using a software algorithm. The V_CC powered counter will automatically record the amount of time
that V_CC 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.
OPERATION
The main elements of the DS1603 are shown in Figure 1. As shown, communications to and from the
elapsed time counter occur over a 3–wire serial port. The port is activated by driving RST to a high state.
With RST at high level 8 bits are loaded into the protocol shift register providing read/write, register
select, register clear, and oscillator trim information. Each bit is serially input on the rising edge of the
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