The power control circuit accepts a VCC " />

      參數(shù)資料
      型號(hào): X1226V8ZT1
      廠商: Intersil
      文件頁數(shù): 21/25頁
      文件大小: 0K
      描述: IC RTC/CALENDAR/4K EE 8-TSSOP
      標(biāo)準(zhǔn)包裝: 2,500
      類型: 時(shí)鐘/日歷
      特點(diǎn): 警報(bào)器,閏年
      時(shí)間格式: HH:MM:SS(12/24 小時(shí))
      數(shù)據(jù)格式: YY-MM-DD-dd
      接口: I²C,2 線串口
      電源電壓: 2.7 V ~ 5.5 V
      電壓 - 電源,電池: 1.8 V ~ 5.5 V
      工作溫度: 0°C ~ 70°C
      安裝類型: 表面貼裝
      封裝/外殼: 8-TSSOP(0.173",4.40mm 寬)
      供應(yīng)商設(shè)備封裝: 8-TSSOP
      包裝: 帶卷 (TR)
      5
      FN8098.3
      May 8, 2006
      POWER CONTROL OPERATION
      The power control circuit accepts a VCC and a VBACK
      input. The power control circuit powers 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 X1226 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.
      CLOCK/CONTROL REGISTERS (CCR)
      The Control/Clock Registers are located in an area
      separate from the EEPROM array and are only
      accessible following a slave byte of “1101111x” and
      reads or writes to addresses [0000h:003Fh]. The
      clock/control memory map has memory addresses
      from 0000h to 003Fh. The defined addresses are
      described in the Table 1. Writing to and reading from
      the undefined addresses are not recommended.
      CCR Access
      The contents of the CCR can be modified by perform-
      ing a byte or a page write operation directly to any
      address in the CCR. Prior to writing to the CCR
      (except the status register), however, the WEL and
      RWEL bits must be set using a two step process (See
      section “Writing to the Clock/Control Registers.”)
      The CCR is divided into 5 sections. These are:
      1. Alarm 0 (8 bytes; non-volatile)
      2. Alarm 1 (8 bytes; non-volatile)
      3. Control (4 bytes; non-volatile)
      4. Real Time Clock (8 bytes; volatile)
      5. Status (1 byte; volatile)
      Each register is read and written through buffers. The
      non-volatile portion (or the counter portion of the RTC) is
      updated only if RWEL is set and only after a valid write
      operation and stop bit. A sequential read or page write
      operation provides access to the contents of only one
      section of the CCR per operation. Access to another sec-
      tion requires a new operation. Continued reads or writes,
      VBACK
      In
      Voltage
      VCC
      On
      Off
      X1226
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