DS1687-5 Maxim Integrated Products, DS1687-5 Datasheet - Page 23

IC RTC 5V 64-BIT Y2K 24-EDIP

DS1687-5

Manufacturer Part Number
DS1687-5
Description
IC RTC 5V 64-BIT Y2K 24-EDIP
Manufacturer
Maxim Integrated Products
Type
Clock/Calendar/NVSRAM/Y2Kr
Datasheet

Specifications of DS1687-5

Memory Size
242B
Time Format
HH:MM:SS (12/24 hr)
Date Format
YY-MM-DD-dd
Interface
Parallel
Voltage - Supply
4.5 V ~ 5.5 V
Operating Temperature
0°C ~ 70°C
Mounting Type
Through Hole
Package / Case
24-DIP (600 mil) Module
Lead Free Status / RoHS Status
Contains lead / RoHS non-compliant
Other names
DS16875

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The RTC address is latched on the falling edge of the ALE signal. Each time an RTC address is latched, the
register address stack is pushed. The stack is only four registers deep, holding the three previous RTC addresses
in addition to the current RTC address being accessed. The following waveform illustrates how the BIOS could
recover the RTC address when an SMI occurs.
1) The RTC address is latched.
2) An SMI is generated before an RTC read or write occurs.
3) RTC address 0Ah is latched and the address from 1 is pushed to the RTC Address-1 stack location. This step
4) RTC address 4Eh is latched and the address from “1” is pushed to location “4Eh,” “RTC Address-2” while 0Ah
ALE
is necessary to change the bank select bit, DV0 = 1.
is pushed to the “RTC Address-1” location. The data in this register, 4Eh, is the RTC address lost due to the
SMI.
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DS1685/DS1687 3V/5V Real-Time Clocks
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