Description, Figure 1. pin assignment – Rainbow Electronics DS1254 User Manual
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DS1254
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DESCRIPTION
The DS1254 is a fully static nonvolatile RAM (NV SRAM) (organized as 2M works by 8 bits) with built-
in real-time clock. It has a self-contained lithium energy source and control circuitry that constantly
monitors V
CC
for an out-of-tolerance condition. When such a condition occurs, the DS1254 makes use of
an attached DS3800 battery cap to maintain clock information and preserve stored data while protecting
that data by disallowing all memory accesses. Additionally, the DS1254 has dedicated circuitry for
monitoring the status of an attached DS3800 battery cap.
The phantom clock provides timekeeping information including hundredths of seconds, seconds, minutes,
hours, day, date, month, and year information. The date at the end of the month is automatically adjusted
for months with fewer than 31 days, including correction for leap years. The phantom clock operates in
either 24- hour or 12- hour format with an AM/PM indicator.
Because the DS1254 has a total of 168 balls and only 35 active signals, balls are wired together into
groups, thus providing redundant connections for every signal.
Figure 1. PIN ASSIGNMENT
V
CC
A7
A6
A5
GND
A4
A3
A2
A1
1
2
3
4
5
6
7
8
9
29
28
27
26
25
24
23
22
21
10
11
12
13
14
15
16
17
18
19
20
41
40
39
38
37
36
35
34
33
32
31
30
V
CC
A17
A18
A19
GND
A20
CE
OE
WE
A0
DQ0
DQ1
DQ2
DQ3
GND
DQ4
DQ5
DQ6
DQ7
BW
V
CC
A8
A9
A10
A11
GND
A12
A13
A14
A15
A16
V
CC
Receptacles for DS3800
Battery Cap pins
GND
V
BAT