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DS12885S 参数 Datasheet PDF下载

DS12885S图片预览
型号: DS12885S
PDF下载: 下载PDF文件 查看货源
内容描述: 实时时钟 [Real-Time Clock]
分类和应用: 外围集成电路光电二极管时钟
文件页数/大小: 22 页 / 259 K
品牌: MAXIM [ MAXIM INTEGRATED PRODUCTS ]
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Real-Time Clock  
Pin Description (continued)  
PIN  
SO,  
PDIP  
NAME  
FUNCTION  
EDIP  
PLCC  
TQFP  
Active-Low Interrupt Request Output. The IRQ pin is an active-low output of the  
device that can be used as an interrupt input to a processor. The IRQ output  
remains low as long as the status bit causing the interrupt is present and the  
corresponding interrupt-enable bit is set. The processor program normally  
reads the C register to clear the IRQ pin. The RESET pin also clears pending  
interrupts. When no interrupt conditions are present, the IRQ level is in the high-  
impedance state. Multiple interrupting devices can be connected to an IRQ  
bus, provided that they are all open drain. The IRQ pin is an open-drain output  
19  
19  
23  
21  
IRQ  
and requires an external pullup resistor to V  
.
CC  
Connection for a Primary Battery. (DS12885 Only.) Battery voltage must be held  
between the minimum and maximum limits for proper operation. If a backup  
supply is not supplied, V  
must be grounded. Connect the battery directly to  
BAT  
20  
21  
24  
25  
22  
24  
V
BAT  
the V  
pin. Diodes in series between the V  
pin and the battery may  
BAT  
BAT  
prevent proper operation. UL recognized to ensure against reverse charging  
when used with a lithium battery.  
Active-Low RAM Clear. The RCLR pin is used to clear (set to logic 1) all the  
general-purpose RAM, but does not affect the RAM associated with the RTC. To  
clear the RAM, RCLR must be forced to an input logic 0 during battery-backup  
21  
RCLR  
(DS12887A/  
DS12C887A)  
mode when V  
is not applied. The RCLR function is designed to be used  
CC  
through a human interface (shorting to ground manually or by a switch) and not  
to be driven with external buffers. This pin is internally pulled up. Do not use an  
external pullup resistor on this pin.  
Square-Wave Output. The SQW pin can output a signal from one of 13 taps  
provided by the 15 internal divider stages of the RTC. The frequency of the  
23  
24  
23  
24  
27  
28  
26  
28  
SQW SQW pin can be changed by programming Register A, as shown in Table 1.  
The SQW signal can be turned on and off using the SQWE bit in Register B. The  
SQW signal is not available when V is less than V  
.
PF  
CC  
DC Power Pin for Primary Power Supply. When V  
is applied within normal  
CC  
limits, the device is fully accessible and data can be written and read. When  
is below V reads and writes are inhibited.  
V
CC  
V
CC  
PF  
5/DS12C87A  
10  
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