Rainbow-electronics DS1644P Uživatelský manuál stáhnout pdf (Strana 3)

DS1644/DS1644P

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DS1644 BLOCK DIAGRAM Figure 1

DS1644 TRUTH TABLE Table 1

CE OE WE

MODE DQ POWER

X X DESELECT HIGH-Z STANDBY

X X X DESELECT HIGH-Z STANDBY

WRITE DATA IN ACTIVE

READ DATA OUT ACTIVE

5V ± 10%

READ HIGH-Z ACTIVE

<4.5V >V

BAT

X X X DESELECT HIGH-Z CMOS STANDBY

BAT

X X X DESELECT HIGH-Z DATA RETENTION

MODE

SETTING THE CLOCK

The MSB Bit, (B7) of the control register is the write bit. Setting the write bit to a 1, like the read bit,

halts updates to the DS1644 registers. The user can then load them with the correct day, date and time

data in 24-hour BCD format. Resetting the write bit to a 0 then transfers those values to the actual clock

counters and allows normal operation to resume.

STOPPING AND STARTING THE CLOCK OSCILLATOR

The clock oscillator may be stopped at any time. To increase the shelf life, the oscillator can be turned off

to minimize current drain from the battery. The

OSC bit is the MSB for the seconds registers. Setting it to

a 1 stops the oscillator.

FREQUENCY TEST BIT

Bit 6 of the day byte is the frequency test bit. When the frequency test bit is set to logic 1 and the

oscillator is running, the LSB of the seconds register will toggle at 512 Hz. When the seconds register is

being read, the DQ0 line will toggle at the 512 Hz frequency as long as conditions for access remain valid

(i.e., CE low, OE low, and address for seconds register remain valid and stable).

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Rainbow-electronics DS1644P Uživatelský manuál Strana 3