DS1225AD-200+

The NE555 IC devices are precision timing circuits capable of producing accurate time delays or oscillation. In the time delay or monostable mode of operation, the timed interval is controlled by a single external resistor and capacitor network. In the a stable mode of operation, the frequency and duty cycle can be controlled independently with two external resistors and a single external capacitor. The threshold and trigger levels normally are two-thirds and one-third, respectively, of VCC. These levels can be altered by use of the control-voltage terminal. When the trigger input falls below the trigger level, the flip-flop is set, and the output goes high. If the trigger input is above the trigger level and the threshold input is above the threshold level, the flip-flop is reset and the output is low. The reset (RESET) input can override all other inputs and can be used to initiate a new timing cycle. When RESET goes low, the flip-flop is reset, and the output goes low. When the output is low, a low impedance path is provided between discharge (DISCH) and ground. The output circuit is capable of sinking or sourcing current up to 200 mA. Operation is specified for supplies of 5V to 15V. With a 5-V supply, output levels are compatible with TTL inputs.

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 permanently to avoid data corruption. The NV SRAMs can be used in place of conventional 8k × 8 SRAMs that are directly compatible with the common byte wide 28-pin DIP standard. The devices also have the same pinout as the 2764 EPROM and 2864 EEPROM, allowing for direct replacement while improving performance. The amount of write cycles that can be performed is not limited, and no extra assistance 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. The number of write cycles that can be performed is not limited, and no extra assistance circuitry is required for microprocessor connection.

The DS1307 Serial Real-Time Clock is a low-power, full binary-coded decimal (BCD) clock/calendar plus 56 bytes of NV SRAM. Address and data are transferred serially via a 2-wire, bi-directional bus. The clock/calendar provides seconds, minutes, hours, day, date, month, and year information. The end of the month date 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 DS1307 has a built-in power sense circuit that detects power failures and automatically switches to the battery supply.