Rainbow Electronics DS1644P - Manual (Page 4)

DS1644/DS1644P
4 of 11
CLOCK ACCURACY (DIP MODULE)
The DS1644 is guaranteed to keep time accuracy to within
±
1 minute per month at 25
°
C. The RTC is
calibrated at the factory by Dallas Semiconductor using nonvolatile tuning elements, and does not require
additional calibration. For this reason, methods of field clock calibration are not available and not
necessary. Clock accuracy is also effected by the electrical environment and caution should be taken to
place the RTC in the lowest level EMI section of the PCB layout. For additional information please see
application note 58.
CLOCK ACCURACY (POWERCAP MODULE)
The DS1644 and DS9034PCX are each individually tested for accuracy. Once mounted together, the
module will typically keep time accuracy to within
±
1.53 minutes per month (35 ppm) at 25°C. Clock
accuracy is also effected by the electrical environment and caution should be taken to place the RTC in
the lowest level EMI section of the PCB layout. For additional information please see application note
58.
DS1644 REGISTER MAP - BANK1 Table 2
DATA
ADDRESS
B
7
B
6
B
5
B
4
B
3
B
2
B
1
B
0
FUNCTION
7FFF - - - - - - - - YEAR 00-99
7FFE X X X - - - - - MONTH 01-12
7FFD X X - - - - - - DATE 01-31
7FFC X FT X X X - - - DAY 01-07
7FFB X X - - - - - - HOUR 00-23
7FFA X - - - - - - - MINUTES 00-59
7FF9
OSC
- - - - - - - SECONDS 00-59
7FF8 W R X X X X X X CONTROL A
OSC = STOP BIT R = READ BIT FT = FREQUENCY TEST
W = WRITE BIT X = UNUSED
NOTE:
All indicated “X” bits are not dedicated to any particular function and can be used as normal RAM bits.