参数资料
型号: DS1554-70IND+
厂商: Maxim Integrated Products
文件页数: 2/18页
文件大小: 0K
描述: IC RTC RAM Y2K 5V 70NS 32-EDIP
产品培训模块: Lead (SnPb) Finish for COTS
Obsolescence Mitigation Program
标准包装: 11
类型: 时钟/日历
特点: 警报器,闰年,NVSRAM,监视计时器,Y2K
存储容量: 32KB
时间格式: HH:MM:SS(24 小时)
数据格式: YY-MM-DD-dd
接口: 并联
电源电压: 4.5 V ~ 5.5 V
工作温度: -40°C ~ 85°C
安装类型: 通孔
封装/外壳: 32-DIP 模块(0.600",15.24mm)
供应商设备封装: 32-EDIP
包装: 管件
DS1554 256k, Nonvolatile, Y2K-Compliant Timekeeping RAM
10 of 18
Figure 4. Backup Mode Alarm Waveforms
USING THE WATCHDOG TIMER
The watchdog timer can be used to detect an out-of-control processor. The user programs the watchdog
timer by setting the desired amount of time-out into the 8-bit Watchdog Register (Address 7FF7h). The
five Watchdog Register bits BMB4 to BMB0 store a binary multiplier and the two lower order bits
RB1-RB0 select the resolution, where 00=1/16 second, 01=1/4 second, 10=1 second, and 11=4 seconds.
The watchdog time-out value is then determined by the multiplication of the 5-bit multiplier value with
the 2-bit resolution value. (For example: writing 00001110 in the Watchdog Register = 3 X 1 second or
3 seconds.) If the processor does not reset the timer within the specified period, the Watchdog Flag (WF)
is set and a processor interrupt is generated and stays active until either the Watchdog Flag (WF) is read
or the Watchdog Register (7FF7) is read or written.
The most significant bit of the Watchdog Register is the Watchdog Steering Bit (WDS). When set to a 0,
the watchdog will activate the IRQ /FT output when the watchdog times out.
When WDS is set to a 1, the watchdog will output a negative pulse on the
RST output for a duration of
40 ms to 200 ms. The Watchdog Register (7FF7) and the FT bit will reset to a 0 at the end of a watchdog
time-out when the WDS bit is set to a 1.
The watchdog timer resets when the processor performs a read or write of the Watchdog Register. The
timeout period then starts over. Writing a value of 00h to the Watchdog Register disables the watchdog
timer. The watchdog function is automatically disabled upon power-up and the Watchdog Register is
cleared. If the watchdog function is set to output to the
IRQ/FT output and the frequency test function is
activated, the watchdog function prevails and the frequency test function is denied.
POWER-ON DEFAULT STATES
Upon application of power to the device, the following register bits are set to 0:
WDS = 0, BMB0 to BMB4 = 0, RB0 to RB1 = 0, AE = 0, and ABE = 0.
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