DS1742(2008) 查看數據表（PDF） - Maxim Integrated
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DS1742 Datasheet PDF : 16 Pages
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DS1742
PIN DESCRIPTION
PIN
NAME
1
A7
2
A6
3
A5
4
A4
5
A3
6
A2
7
A1
8
A0
19
A10
22
A9
23
A8
9
DQ0
10
DQ1
11
DQ2
13
DQ3
14
DQ4
15
DQ5
16
DQ6
17
DQ7
12
GND
18
CE
20
OE
21
WE
24
VCC
FUNCTION
Address Input
Data Input/Output
Ground
Active-Low Chip-Enable Input
Active-Low Output-Enable Input
Active-Low Write-Enable Input
Power-Supply Input
DESCRIPTION
The DS1742 is a full-function, year 2000-compliant (Y2KC), real-time clock/calendar (RTC) and
2k x 8 nonvolatile static RAM. User access to all registers within the DS1742 is accomplished
with a bytewide interface as shown in Figure 1. The RTC information and control bits reside in
the eight uppermost RAM locations. The RTC registers contain century, year, month, date, day,
hours, minutes, and seconds data in 24-hour BCD format. Corrections for the day of the month
and leap year are made automatically.
The RTC clock registers are double-buffered to avoid access of incorrect data that can occur
during clock update cycles. The double-buffered system also prevents time loss as the
timekeeping countdown continues unabated by access to time register data. The DS1742 also
contains its own power-fail circuitry, which deselects the device when the VCC supply is in an
out-of-tolerance condition. This feature prevents loss of data from unpredictable system
operation brought on by low VCC as errant access and update cycles are avoided.
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