RV-3049 datasheet(38/65 Pages) MICROCRYSTAL

38 / 65 page

Micro Crystal

DTCXO Temperature Compensated Real Time Clock / Calendar Module

RV-3049

38/65

5.2. COMPENSATION PRINCIPLE

The Frequency Compensation Unit “FCU” is calculating every 32 seconds a Frequency Compensation Value

based on individual device data:

•

XTAL offset:

Device individual frequency deviation ±20ppm @ 25°C

•

XTAL T0:

Xtal’s turnover temperature 25°C ±5°C

•

XTAL temp. coefficient: Xtal’s frequency drift vs. temperature -0.035 ppm * (T-T0)

2 ±10%

•

Temperature:

Measured ambient temperature

Calculating the Anticipated Frequency Deviation and the Time Compensation Value

-400

-350

-300

-250

-200

-150

-100

-50

100

150

200

250

300

350

400

-50

-40

-30

-20

-10

100

110

120

130

140

Temperature [°C]

Note:

The 32.768 kHz frequency is adjusted according to the calculated Time Compensation value.

The compensation itself is achieved by adding or subtracting clock-pulses to the 32.768 kHz reference clock.

One complete compensation period takes 32 seconds.

XTAL Temperature Coefficient

∆

f/f [ppm] = -0.035 * (Tamb-T0)

2 (+/-10%)

XTAL T0

T0 = 25°C (+/-5°C)

XTAL OFFSET

∆

f/f = +/-20 ppm

Calculated Time

Compensation Value

RV-3049 Datasheet(PDF) 38 Page - MICORO CRYSTAL SWITZERLAND

RV-3049 Datasheet(HTML) 38 Page - MICORO CRYSTAL SWITZERLAND

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