ICM7170AIBG

The clock in the ICM7170 is set or read by accessing the 8 internal separately addressable and programmable counters from 1/100 seconds to years. The counters are controlled by a pulse train divided down from a crystal oscillator circuit, and the frequency of the crystal is selectable with the on-chip command register. An extremely stable oscillator frequency is achieved through the use of an on-chip regulated power supply. The device access time (t ACC) of 300ns eliminates the need for a backup pin to be pulled up to V DD through a 2K resistor. Time synchronization is achieved through bit D3 of the Command Register, which enables or disables the 100Hz clock from the counters. To accurately set the time, a logic “0” should be written into D3 and then the desired times entered into the appropriate counters. The clock is then started at the proper time by writing a logic “1” into D3 of the Command Register. Latched Data is used to prevent ambiguity while the processor is gathering data from the registers, incorporating data latches and a transparent transition delay circuit.

The main feature of the ICM7170 real-time clock is its compatibility with microprocessor bus, allowing for direct addressing or multiplexed addressing. It also features a regulated oscillator supply for frequency stability and low power consumption. The clock can measure time from 1/100 seconds to 99 years and offers software-selectable 12/24 hour format. Additionally, it has a full calendar with automatic leap year correction and on-chip battery backup switchover circuit. The device has a fast access time of less than 300ns and offers various programmable crystal oscillator frequencies. It also includes an on-chip alarm comparator and RAM, as well as interrupts from alarm and selectable periodic intervals. The ICM7170 is suitable for applications in portable and personal computers, data logging, industrial control systems, and point of sale.

The ICM7170 can generate two types of interrupts: periodic and alarm. The periodic interrupt can be programmed to provide 6 different output signals, while the alarm interrupt is activated when the real-time counter and alarm RAM time are equal.