DS12887A

DS12887A Application Field and Working Principle

Real Time Clocks - The DS12887A is an integrated circuit which combines the functions of a real time clock (RTC) and a personal computer peripheral. It is primarily used in PCs and as an ancillary component in disk drives, network interface cards and other peripherals.

The DS12887A contains logic to interpret commands supplied by the host microprocessor, such as read and write, and to interpret the data received and placed in memory. It also contains a battery to power the clock system, a register to store the time, and a register to store the control and status information.

The DS12887A\'s clock oscillator is a 32.768 kHz quartz crystal, which allows the time period to be extremely accurate. In order to power the quartz and to carry out the clock operations, the DS12887A requires a periodic supply of power which is supplied in standby mode. Consequently, the time and date remains accurate although the computer is switched off.

In operation, the processor communicates with the DS12887A by issuing commands, such as read and write, to the register. The register is then able to access the clock through the communication lines between the processor and the RTC. This communication takes place through a serial peripheral interface known as SPI, which is the standard used for a real-time clock.

Based on the I2C protocol, the RTC communicates with the main processor by sending two bytes of data to verify the current time and then subsequently, the current time value is sent back in a two-byte format. The I2C protocol is relatively simple as it only requires two wires - a transmission line and a receive line - and no external capacitor, making it more suited for use in personal computers.

The DS12887A can be used in a variety of applications, such as embedded applications and automotive systems. In embedded applications, the device can be used to set alarms, to detect power-failure events, to monitor temperature and to control the system\'s operation. In automotive systems, the DS12887A can be used to indicate time-to-travel, to measure trip times and to detect brake failures.

The DS12887A also includes a number of features to improve its performance and long-term reliability. These features include low-voltage and battery low detect, automatic timer write, and an EEPROM to store up to 256 bytes of data. Additionally, the chip has a range of built-in interrupts to provide notification of events, such as an external power failure or an RTC event.

In conclusion, the DS12887A is a versatile chip which can be deployed in a variety of applications. It can be used to provide accurate timing and storage information, making it an invaluable part of any embedded computer system. Furthermore, thanks to its I2C protocol, it can be implemented in both embedded and automotive systems with ease.