RV-3049 datasheet(42/65 Pages) MICROCRYSTAL

42 / 65 page

Micro Crystal

DTCXO Temperature Compensated Real Time Clock / Calendar Module

RV-3049

42/65

Effect of correction clocks:

•

CLKOUT 32.768 kHz:

not affected, this frequency is not compensated

•

CLKOUT 1024 / 32 / 1 Hz: affected, these frequencies are compensated

•

Timer / INT Output:

affected; the internal Timer Source Clocks are compensated

•

Time / Date

affected; time & date information are compensated

5.3.1.CORRECT METHOD FOR TESTING THE TIME ACCURACY

The compensation method of adding or subtracting correction clocks is changing the period of a single second;

therefore the duration of single seconds may vary within a compensation cycle of 32 seconds.

For a test result correctly representing the time accuracy of the RTC module, it is mandatory to measure the device

during one complete compensation cycle of 32 seconds.

When the device is tested over a shorter period of time, an error will be caused by the test method and shall be

considered for interpretation of the test-results:

Measuring Time

Resolution of Compensation Method

Test Error / Deviation per Day

1 second

± 1 clock

(32.768 kHz)

± 30.5 ppm / ± 2.7 sec. per day

2 seconds

± 1 clock

(32.768 kHz)

± 15.3 ppm / ± 1.3 sec. per day

4 seconds

± 1 clock

(32.768 kHz)

± 7.7 ppm / ± 0.7 sec. per day

8 seconds

± 1 clock

(32.768 kHz)

± 3.9 ppm / ± 0.4 sec. per day

32 seconds

± 1 clock

(32.768 kHz)

represents real performance

5.3.2.TESTING THE TIME ACCURACY USING CLKOUT OUTPUT

The simplest method to test the time accuracy of the Frequency Compensation Unit (FCU) is by measuring the

compensated frequencies at the CLKOUT pin.

Enable temperature compensation:

•

Select scanning interval 1 s:

set “ThP” = “0” (bit 0 register EEPROM Control)

•

Enable thermometer:

set “ThE” = “1” (bit 1 register EEPROM Control)

Select compensated frequency at CLKOUT:

•

Set CLKOUT frequency:

set “FD0” / “FD1” (bits 1&3 register EEPROM Control) to select

CLKOUT frequency = 1024Hz or alternatively 1Hz

Measuring equipment and setup:

•

Use appropriate frequency counter:

for example Agilent A53132A Universal Counter

•

Correct setup:

set gate time to 32 seconds (one complete compensation cycle)

to measure frequency and calculate time deviation upon the

measured frequency deviation

RV-3049 Datasheet(PDF) 42 Page - MICORO CRYSTAL SWITZERLAND

RV-3049 Datasheet(HTML) 42 Page - MICORO CRYSTAL SWITZERLAND

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