'real-time' related articles 2

  1. 2009/03/24 S-35199A01 - 3-WIRE REAL-TIME CLOCK
  2. 2008/04/23 PT7C4307 - Real-time Clock Module (I2C Bus)
The S-35199A01 is a CMOS 3-wire real-time clock IC which operates with the very low current consumption and in the wide range of operation voltage. The operation voltage is 1.3 V to 5.5 V so that this IC can be used for various power supplies from main supply to backup battery. Due to the 0.34 μA current consumption and wide range of power supply voltage at time keeping, this IC makes the battery life longer. In the system which operates with a backup battery, the included free registers can be used as the function for user’s backup memory. Users always can take back the information in the registers which is stored before power-off the main power supply, after the voltage is restored.
This IC has the function to correct advance/delay of the clock data speed, in the wide range, which is caused by the oscillation circuit’s frequency deviation. Correcting according to the temperature change by combining this function and a temperature sensor, it is possible to make a high precise clock function which is not affected by the ambient temperature. This IC has the function for the external microcomputer’s sub clock to output the 32.768 kHz clock pulse. And for this output, users can select either of Nch open drain or CMOS.
Moreover, this IC has a 24-bit binary up counter. This counter counts up every 60 sec from power-on so that users are able to grasp the elapsed time from power-on up to 30 years.

*Low current consumption : 0.34 μA typ. (VDD = 3.0 V, Ta = 25°C)
*Wide range of operating voltage : 1.3 to 5.5 V
*Built-in clock-correction function
*Clock pulse output (CMOS output, function to select frequency)
*32.768 kHz clock pulse output (Nch open-drain, output control pin)
*Built-in 24-bit binary up counter
*Built-in free user register
*3-wire (micro wire) CPU interface
*Built-in alarm interrupter
*Built-in flag generator during detection of low power voltage or at power-on
*Auto calendar up to the year 2099, automatic leap year calculation function
*Built-in constant voltage circuit
*Built-in 32.768 kHz crystal oscillator (Cd built in, Cg external)
*Package : WLP-12A
*Lead-free product

*Mobile game devices
*Mobile AV devices
*Digital still cameras
*Digital video cameras
*Electronic power meters
*DVD recorders
*TVs, VCRs
*Mobile phones, PHS
*Car navigation


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Product Description
 The PT7C4307 serial real-time clock is a low-power clock/calendar with a programmable square-wave output and 56 bytes of nonvolatile RAM.
Address and data are transferred serially via a 2-wire, bidirectional bus.
The clock/calendar provides seconds, minutes, hours, day, date, month, and year information.
The date at the end of the month is automatically adjusted for months with fewer than 31 days, including corrections for leap year.
The clock operates in either the 24-hour or 12-hour format with AM/PM indicator.
The PT7C4307 has a built-in power sense circuit that detects power failures and automatically switches to the battery supply.

Product Features
• Using external 32.768kHz quartz crystal
• Supports I2C-Bus's high speed mode (400 kHz)
• Includes time (Hour/Minute/Second) and calendar (Year/Month/Date/Day) counter functions (BCD code)
• Programmable square wave output signal
• 56-byte, battery-backed, nonvolatile (NV) RAM for data storage
• Automatic power-fail detect and switch circuitry of battery backup
• Consumes less than 500nA in battery backup mode with oscillator running


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