RV-3049 datasheet(40/65 Pages) MICROCRYSTAL

40 / 65 page

Micro Crystal

DTCXO Temperature Compensated Real Time Clock / Calendar Module

RV-3049

40/65

5.2.2.SETTING THE FREQUENCY COMPENSATION PARAMETERS

In order to achieve best time accuracy, correct parameters have to be stored into the corresponding registers of the

EEPROM Control page.

Attention: these parameters are factory calibrated, it is recommended not to modify these register values.

XTAL Offset (address 31h…bits description)

Address

Function

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

31h

XTAL Offset

sign

Bit

Symbol

Value

Description

Sign

- Deviation (slower) of 32.768kHz frequency at T0

+ Deviation (faster) of 32.768kHz frequency at T0

6 to 0

XTAL Offset

0 to 121

Frequency Offset Compensation value

The register value “XTAL Offset” is used by the Frequency Compensation Unit “FCU” to compensate the initial

frequency deviation of the 32.768 kHz clock at the crystal’s turnover temperature “XTAL T0”.

The required register value “XTAL Offset” is calculated as follow:

XTAL Offset = XtalOFFSET x 1.05

XTAL COEF Temperature Coefficient (address 32h…bits description)

Address

Function

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

32h

XTAL Coef

128

Bit

Symbol

Value

Description

Reference

7 to 0

XTAL Coef

0 to 255

Quadratic Coefficient of XTAL’s Temperature Drift

1) The factory programmed register value XTAL Coef may also contain thermometer error compensation.

The register value “XTAL Coef” is used by the Frequency Compensation Unit “FCU” to compensate the frequency

deviation caused by 2

nd order temperature coefficient of the 32.768 kHz crystal (frequency drift vs temperature).

The required register value “XTAL Coef” is calculated as follow:

XTAL Coef = XtalTEMPERATURE COEFFICIENT x 4096 x 1.05

XTAL T0 Turnover Temperature (address 33h…bits description)

Address

Function

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

33h

XTAL T0

Bit

Symbol

Value

Description

Reference

7 to 6

unused

5 to 0

XTAL T0

4 to 67

XTAL’s Turnover Temperature in °C

1) The factory programmed register value XTAL T

0 may also contain thermometer error compensation.

The register value “XTAL T0” is used by the Frequency Compensation Unit “FCU” to compensate the frequency

deviation caused by the turnover temperature T0 of the 32.768 kHz crystal.

The required register value “XTAL T0” is calculated as follow:

XTAL T0 = XtalTURNOVER TEMP T0 - 4

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