DS1554 Datasheet, PDF (1/21 Pages) Dallas Semiconductor – 256K NV Y2KC Timekeeping RAM

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PRELIMINARY
DS1554
256K NV Y2KC Timekeeping RAM
FEATURES
Integrated NV SRAM, real time clock, crystal,
power-fail control circuit and lithium energy
source
Clock registers are accessed identically to the
static RAM; these registers are resident in the
16 top RAM locations
Century byte register; i.e., Y2K complaint
Totally nonvolatile with over 10 years of
operation in the absence of power
Precision power-on reset
Programmable watchdog timer and RTC alarm
BCD coded year, month, date, day, hours,
minutes, and seconds with automatic leap year
compensation valid up to the year 2100
Battery voltage level indicator flag
Power-fail write protection allows for ±10%
V_CC power supply tolerance
Lithium energy source is electrically
disconnected to retain freshness until power is
applied for the first time
PIN ASSIGNMENT
RST 1
A16 ₂
A14 3
A12 4
A7 5
A6 6
A5 7
A4 8
A3 9
A2 10
A1 11
A0 ¹²
DQ0 ¹³
DQ1 14
DQ2 15
GND 16
32
VCC
31 NC
30 IRQ/FT
29 WE
28 A13
27 A8
26 A9
25 A11
24 ^OE
23 A10
22
CE
21 DQ7
20 DQ6
19 DQ5
18 DQ4
17 DQ3
32-PIN ENCAPSULATED PACKAGE
IRQ/FT ¹
34
NC
NC ²
NC ³
RST ⁴
VCC
WE
5
6
OE ⁷
CE
DQ7
8
9
33
NC
32
A14
31
A13
30
A12
29
A11
28
A10
27
A9
26
A8
DQ6 ¹⁰
25
A7
DQ5 ¹¹
DQ4 12
24
A6
23
A5
DQ3 ¹³
22
A4
DQ2
DQ1
DQ0
14
21
15
16
X1 GND VBAT X2
20
19
A3
A2
A1
GND ¹⁷
18
A0
34-Pin POWERCAP MODULE BOARD
(USES DS9034PCX POWERCAP)
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