The DS1554 is a full-function, year 2000-compliant (Y2KC), real-time clock/calendar (RTC) with an RTC alarm, watchdog timer, power-on reset, battery monitor, and 32k x 8 nonvolatile static RAM. User access to all registers within the DS1554 is accomplished with a byte-wide interface as shown in Figure 1.The RTC registers contain century, year, month, date, day, hours, minutes, and seconds data in 24-hour binary-coded decimal (BCD) format. Corrections for day of month and leap year are made automatically.

The RTC registers are double-buffered into an internal and external set. The user has direct access to the external set. Clock/calendar updates to the external set of registers can be disabled and enabled to allow the user to access static data. Assuming the internal oscillator is turned on, the internal set of registers is continuously updated; this occurs regardless of external registers settings to guarantee that accurate RTCinformation is always maintained.

The DS1554 has interrupt (active-low IRQ/FT) and reset (active-low RST) outputs which can be used to control CPU activity. The active-low IRQ/FT interrupt output can be used to generate an external interrupt when the RTC Register values match user programmed alarm values. The interrupt is always available while the device is powered from the system supply and can be programmed to occur when in the battery-backed state to serve as a systemwakeup. Either the active-low IRQ/FT or active-low RST outputs can also be used as a CPU watchdog timer, CPU activity is monitored and an interrupt or reset output will be activated if the correct activity is not detected within programmed limits. The DS1554 power-on reset can be used to detect a system power down or failure and hold the CPU in a safe reset state until normal power returns and stabilizes; the active-low RST output is used for this function.

The DS1554 also contains its own power-fail circuitry, which automatically deselects the device when the VCC supply enters an out of tolerance condition. This feature provides a high degree of data security during unpredictable system operation brought on by low VCC levels.

• MAX14753 - 8通道/双4通道72V模拟复用器
• MAX13052 - 工业标准高速CAN收发器，具有±80V故障保护
• MAX1963A - 低输入电压、300mA LDO稳压器，带有RESET，SOT或TDFN封装
• MAX4928A - DisplayPort/PCIe无源开关
• MAX6018A - 高精度、微功耗、1.8V电源、低压差、SOT23封装电压基准
• MAX6437 - 低功耗、单/双电平电池监测器，带有滞回
• MAX6763 - 低功耗、单/双电压窗检测器
• MAX11632 - 12位、300ksps ADC，带有FIFO和内部电压基准
• MAX111 - 低成本、2通道、±14位串行ADC
• MAX1205 - +5V单电源、1Msps、14位自校准ADC