DESCRIPTION
The MSM6542 is a perpetual-calendar-based real time clock with an alarm function which can read and write data in units of seconds. It can be connected to various buses and can function as a peripheral IC of a microcomputer.

FEATURES
• Real time clock providing seconds, minutes, hours, days, months, years, and days of the week.
• Multiple alarm ranges covering seconds, minutes, hours, days, months, and days of the week. A desired alarm range can be selected.
• A periodic interrupt output interval can be selected over a wide range from 1/1024 seconds up to 10 minutes.
• Interface flexibility allows for connection to many types of microprocessors.
• Single read-out procedure (Read flag).
• Single power sense circuitry. (Data protect function).
• Unused registers can be used as RAM.
• 30-second adjustment by software or hardware (software only for the MSM6542-1/-2).
• Stop and restart of clock by software or hardware (software only for the MSM6542-1/-2).
• 1 Hz output for adjustment and check of oscillation frequency (MSM6542-3 only).
• User selection of 12 or 24 hour clock mode.
• Address latch enable (ALE) input pin.
• Advanced CMOS circuitry allows low stand-by voltage and current.
• User standard 32.768 kHz oscillator crystal
• Available in multiple packages
    18-pin plastic DIP (for the MSM6542-1RS/2RS) (DIP18-P-300).
    20-pin plastic SOP (for the MSM6542-1MS-K/2MS-K) (SSOP20-P-250-K).
    24-pin plastic DIP (for the MSM6542-3RS) (DIP24-P-600).
    24-pin plastic SOP (for the MSM6542-3GS-VK) (SOP24-P-430-VK).
• Pin assignment compatibility with the MSM6242BRS (The MSM6542-3MSK provides near compatibility.).