Motore di ricerca datesheet componenti elettronici |
|
FM30C256 Scheda tecnica(PDF) 6 Page - List of Unclassifed Manufacturers |
|
FM30C256 Scheda tecnica(HTML) 6 Page - List of Unclassifed Manufacturers |
6 / 18 page FM30C256 Rev 2.1 Dec. 2002 Page 6 of 18 32.768 kHz crystal Oscillator Clock Divider Update Logic 512 Hz W R Seconds 7 bits Minutes 7 bits Hours 6 bits Date 6 bits Months 5 bits Years 8 bits CF Days 3 bits User Interface Registers 1 Hz Figure 2. Real-time Clock Core Block Diagram Calibration When the CAL bit in register 0 is set to 1, the clock enters calibration mode. Calibration operates by applying a digital correction to the counter based on the frequency error. In CAL mode, the CAL pin is driven with a 512 Hz (nominal) square wave. Any measured deviation from 512 Hz is converted to an error in ppm. This error corresponds to a correction value that is then written by the user into the calibration register. The correction factors are listed in the table below. Positive ppm errors require a negative adjustment that removes pulses. Negative ppm errors require a positive correction that adds pulses. Positive ppm adjustments have the CALS bit set to 1, where as negative ppm adjustments have CALS = 0. After calibration, the clock will have a maximum error of ± 2.17 ppm or ± 0.09 minutes per month at the calibrated temperature. The calibration setting is battery backed and is stored in bits CAL.4-0. This value only can be written when the CAL bit is set to a 1. To exit the calibration mode, the user must clear the CAL bit to a 0. When the CAL bit is 0, the CAL pin will be driven low. When the calibration mode is entered, the user can measure the frequency error on the CAL pin. This error expressed in ppm translates directly into timekeeping error. An offsetting calibration adjustment corrects this error. However, the correction is applied by adding or removing pulses on a periodic basis. Therefore, the correction will not appear on the 512 Hz output. The calibration correction must be applied using the lookup table below. The timekeeping accuracy can be verified by comparing the FM30C256 time to a reference source. |
Codice articolo simile - FM30C256 |
|
Descrizione simile - FM30C256 |
|
|
Link URL |
Privacy Policy |
ALLDATASHEETIT.COM |
Lei ha avuto il aiuto da alldatasheet? [ DONATE ] |
Di alldatasheet | Richest di pubblicita | contatti | Privacy Policy | scambio Link | Ricerca produttore All Rights Reserved©Alldatasheet.com |
Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
Family Site : ic2ic.com |
icmetro.com |