Os motores de busca de Datasheet de Componentes eletrônicos |
|
X1228S14IZ-2.7A Folha de dados(PDF) 10 Page - Intersil Corporation |
|
X1228S14IZ-2.7A Folha de dados(HTML) 10 Page - Intersil Corporation |
10 / 29 page 10 FN8100.2 October 17, 2005 X1, X2 The X1 and X2 pins are the input and output, respectively, of an inverting amplifier. An external 32.768kHz quartz crystal is used with the X1228 to supply a timebase for the real time clock. The recommended crystal is a Citizen CFS206-32.768KDZF. Internal compensation circuitry is included to form a complete oscillator circuit. Care should be taken in the placement of the crystal and the layout of the circuit. Plenty of ground plane around the device and short traces to X1 and X2 are highly recommended. See Application section for more recommendations. Figure 1. Recommended Crystal connection POWER CONTROL OPERATION The power control circuit accepts a VCC and a VBACK input. The power control circuit power the clock from VBACK when VCC < VBACK - 0.2V. It will switch back to power the device from VCC when VCC exceeds VBACK. Figure 2. Power Control REAL TIME CLOCK OPERATION The Real Time Clock (RTC) uses an external 32.768kHz quartz crystal to maintain an accurate inter- nal representation of the second, minute, hour, day, date, month, and year. The RTC has leap-year correc- tion. The clock also corrects for months having fewer than 31 days and has a bit that controls 24 hour or AM/PM format. When the X1228 powers up after the loss of both VCC and VBACK, the clock will not operate until at least one byte is written to the clock register. Reading the Real Time Clock The RTC is read by initiating a Read command and specifying the address corresponding to the register of the Real Time Clock. The RTC Registers can then be read in a Sequential Read Mode. Since the clock runs continuously and a read takes a finite amount of time, there is the possibility that the clock could change during the course of a read operation. In this device, the time is latched by the read command (falling edge of the clock on the ACK bit prior to RTC data output) into a separate latch to avoid time changes during the read operation. The clock continues to run. Alarms occurring during a read are unaffected by the read operation. Writing to the Real Time Clock The time and date may be set by writing to the RTC registers. To avoid changing the current time by an uncompleted write operation, the current time value is loaded into a separate buffer at the falling edge of the clock on the ACK bit before the RTC data input bytes, the clock continues to run. The new serial input data replaces the values in the buffer. This new RTC value is loaded back into the RTC Register by a stop bit at the end of a valid write sequence. An invalid write operation aborts the time update procedure and the contents of the buffer are discarded. After a valid write operation the RTC will reflect the newly loaded data beginning with the next “one second” clock cycle after the stop bit is written. The RTC continues to update the time while an RTC register write is in progress and the RTC continues to run during any nonvolatile write sequences. A single byte may be written to the RTC without affecting the other bytes. Accuracy of the Real Time Clock The accuracy of the Real Time Clock depends on the frequency of the quartz crystal that is used as the time base for the RTC. Since the resonant frequency of a crystal is temperature dependent, the RTC perfor- mance will also be dependent upon temperature. The frequency deviation of the crystal is a fuction of the turnover temperature of the crystal from the crystal’s nominal frequency. For example, a >20ppm frequency deviation translates into an accuracy of >1 minute per month. These parameters are available from the crystal manufacturer. Intersil’s RTC family provides on-chip crystal compensation networks to adjust load- capacitance to tune oscillator frequency from +116 ppm to -37 ppm when using a 12.5 pF load crystal. For more detail information see the Application section. X1 X2 VBACK In Voltage VCC On Off X1228 |
Nº de peça semelhante - X1228S14IZ-2.7A |
|
Descrição semelhante - X1228S14IZ-2.7A |
|
|
Ligação URL |
Privacy Policy |
ALLDATASHEETPT.COM |
ALLDATASHEET é útil para você? [ DONATE ] |
Sobre Alldatasheet | Publicidade | Contato conosco | Privacy Policy | roca de Link | Lista de Fabricantes 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 |