DS1689(2000) View Datasheet(PDF) - Dallas Semiconductor -> Maxim Integrated

Part Name

Description

Manufacturer

DS1689
(Rev.:2000)

3-Volt/5-Volt Serialized Real-Time Clock with NV RAM Control

Dallas Semiconductor -> Maxim Integrated 

PERIODIC INTERRUPT RATE AND

SQUARE WAVE OUTPUT FREQUENCY Table 2

EXT. REG. B SELECT BITS REGISTER A

tPI PERIODIC

E32K

RS3 RS2 RS1 RS0 INTERRUPT RATE

0

0

0

0

0

None

0

0

0

0

1

3.90625 ms

0

0

0

1

0

7.8125 ms

0

0

0

1

1

122.070 ms

0

0

1

0

0

244.141 ms

0

0

1

0

1

488.281 ms

0

0

1

1

0

976.5625 ms

0

0

1

1

1

1.953125 ms

0

1

0

0

0

3.90625 ms

0

1

0

0

1

7.8125 ms

0

1

0

1

0

15.625 ms

0

1

0

1

1

31.25 ms

0

1

1

0

0

62.5 ms

0

1

1

0

1

125 ms

0

1

1

1

0

250 ms

0

1

1

1

1

500 ms

1

X

X

X

X

*

*RS3-RS0 determine periodic interrupt rates as listed for E32K=0.

DS1689/DS1693

SQW OUTPUT

FREQUENCY

None

256 Hz

128 Hz

8.192 kHz

4.096 kHz

2.048 kHz

1.024 kHz

512 Hz

256 Hz

128 Hz

64 Hz

32 Hz

16 Hz

8 Hz

4 Hz

2 Hz

32.768 kHz

The third method uses a periodic interrupt to determine if an update cycle is in progress. The UIP bit in

Register A is set high between the setting of the PF bit in Register C (see Figure 3). Periodic interrupts

that occur at a rate of greater than tBUC allow valid time and date information to be reached at each

occurrence of the periodic interrupt. The reads should be complete within (tPI / 2+tBUC) to ensure that data

is not read during the update cycle.

UPDATE-ENDED AND PERIODIC INTERRUPT RELATIONSHIP Figure 3

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