DS1232 MicroMonitor Chip

RTC DS 12C887 is widely used to provide exact time and date in many applications such as x86 IBM PC. This RTC provides time components hour, minute and second in addition to the date/calendar components of year, month and day. This chip uses an internal lithium battery, which keeps the time and date updated even when the power is off. The DS12C887 works on CMOS technology to keep the power consumption low. It has a total of 128 bytes of non volatile RAM. It uses 14 bytes of RAM for storing the values of clock/calendar and control registers. The rest 114 bytes of RAM are for general purpose data storage. The internal registers are accessible only when the RTC is powered by an external power source. When the external power is turned off, the RTC clock keeps running from the internal lithium battery source but the internal registers of the RTC cannot be accessed. RTC 12C887 becomes active when a voltage greater than 4.25V is applied and the internal registers can be accessed after 200 msec.

The DS1225AB and DS1225AD are 65,536-bit nonvolatile SRAMs that are structured as 8192 words by 8 bits. Each NV SRAM contains its own lithium energy source as well as control circuitry that constantly monitors VCC for out-of-tolerance conditions. When this occurs, the lithium energy source is automatically activated, and write protection is enabled unconditionally to avoid data corruption. The NV SRAMs can be used in place of existing 8k × 8 SRAMs that are directly compatible with the common bytewide 28-pin DIP standard. The devices also have the same pinout as the 2764 EPROM and 2864 EEPROM, allowing for straightforward replacement while improving performance. The number of write cycles that can be performed is not limited, and no additional support circuitry is required for microprocessor connection.

The DS1230 256k Nonvolatile SRAMs have a capacity of 262,144 bits and are structured as 32,768 words by 8 bits. Each NV SRAM contains its own lithium energy source as well as control circuitry that constantly monitors VCC for out-of-tolerance conditions. When this occurs, the lithium energy source is automatically activated, and write protection is enabled unconditionally to avoid data corruption. The DS1230 DIP-package devices can be utilized in place of current 32k × 8 static RAMs that directly comply to the common byte wide 28-pin DIP standard. The pinout of the DIP devices matches that of the 28256 EEPROMs, allowing for straightforward substitution while improving performance. The Low Profile Module package of DS1230 devices is specifically suited for surface-mount applications. There is no limit to the number of write cycles that can be performed.