DS1495 Datasheet, PDF (1/19 Pages) Dallas Semiconductor – RAMified Real Time Clock

DS1495/DS1497
DS1495/DS1497
RAMified Real Time Clock
FEATURES
• Ideal for EISA bus PCs
• Functionally compatible with MC146818 in 32 KHz
mode
• Totally nonvolatile with over 10 years of operation in
the absence of power
• Self-contained subsystem includes lithium, quartz,
and support circuitry
• Counts seconds, minutes, hours, day of the week,
date, month, and year with leap year compensation
• Binary or BCD representations of time, calendar, and
alarm
• 12- or 24-hour clock with AM and PM in 12-hour mode
• Daylight Savings Time option
• Interfaced with software as 64 register/RAM locations
plus 8K x 8 of static RAM
– 14 bytes of clock and control registers
– 50 bytes of general and control registers
– Separate 8K x 8 nonvolatile SRAM
• Programmable square wave output signal
• Bus-compatible interrupt signals (IRQ)
• Three interrupts are separately software-maskable
and testable:
– Time-of-day alarm once/second to once/day
– Periodic rates from 122 µs to 500 ms
– End-of-clock update cycle
• 28-pin JEDEC footprint
• Available as chip (DS1495/DS1495S) or stand alone
module with embedded lithium battery and crystal
(DS1497)
ORDERING INFORMATION
DS1495
DS1495S
DS1497
RTC Chip; 28–pin DIP
RTC Chip; 28–pin SOIC
RTC Module; 28–pin DIP
PIN ASSIGNMENT
A0
1
A1
2
X2
3
X1
4
STBY
5
D0
6
D1
7
D2
8
D3
9
D4
10
D5
11
D6
12
D7
13
VSS
14
28 A2
27 A3
26
VDD
25 SQW
24 A4
23 A5
22 VBAT
21 ^IRQ
20 ^RESET
19 ^RD
18 ^BGND
17 ^WR
16 ^XRAM
15 ^RTC
DS1495S 28-Pin SOIC (330 mil)
A0 ¹
A1 2
X2 ³
X1 4
STBY 5
D0 ⁶
D1 ⁷
D2 ⁸
D3 ⁹
D4 ¹⁰
D5 ¹¹
D6 12
D7 13
VSS 14
28 A2
27 A3
26 ^VDD
25 SQW
24 A4
23 A5
22 ^VBAT
21 ^IRQ
20 ^RESET
19 ^RD
18 ^BGND
17 WR
16 XRAM
15 RTC
DS1495 28-Pin DIP (600 mil)
A0 1
A1 2
NC 3
NC 4
STBY ⁵
D0 6
D1 7
D2 8
D3 9
D4 10
D5 11
D6 12
D7 13
V _SS 14
28 A2
27 A3
26 VDD
25 ^SQW
24 ^A4
23 A5
22 ^NC
21 ^IRQ
20 RESET
19 ^RD
18 NC
17 WR
16 XRAM
15 RTC
DS1497 28-Pin Encapsulated Package (720 mil)
ECopyright 1995 by Dallas Semiconductor Corporation.
All Rights Reserved. For important information regarding
patents and other intellectual property rights, please refer to
Dallas Semiconductor databooks.
020894 1/19