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Teilenummer | DS1497 |
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Beschreibung | (DS1495 / DS1497) RAMified Real Time Clock | |
Hersteller | Dallas Semiconductor | |
Logo | ||
Gesamt 19 Seiten 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
www.DataSheet4U.comthe 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
A1
X2
X1
STBY
D0
D1
D2
D3
D4
D5
D6
D7
VSS
1
2
3
4
5
6
7
8
9
10
11
12
13
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
A1
X2
X1
STBY
D0
D1
D2
D3
D4
D5
D6
D7
VSS
1
2
3
4
5
6
7
8
9
10
11
12
13
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
A1
NC
NC
STBY
D0
D1
D2
D3
D4
D5
D6
D7
V SS
1
2
3
4
5
6
7
8
9
10
11
12
13
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
DS1495/DS1497
REAL TIME CLOCK RAM MAP Figure 2
RTC
INDIRECT ADDRESS REGISTER
RTC +1
INDIRECT
ADDRESS
00
13
14
www.DataSheet4U.com
63
RTC DATA REGISTER
14–BYTES
RTC
50–BYTES
USER RAM
00
0D
0E
3F
EXTENDED RAM ADDRESS MAP Figure 3
14– BYTES
REAL TIME CLOCK
00 SECONDS
01 SECONDS ALARM
02 MINUTES
03 MINUTES ALARM
04 HOURS
05 HOURS ALARM
06 DAY OF WEEK
07 DAY OF MONTH
08 MONTH
09 YEAR
0A REGISTER A
0B REGISTER B
0C REGISTER C
0D REGISTER D
020894 6/19
XRAM
THRU
XRAM + 1F
XRAM + 20
XRAM + 21
THRU
XRAM + 3F
256 PAGES
OF 32–BYTES
EXTENDED RAM
PAGE FF
02
01
PAGE 00
XRAM PAGE REGISTER
ALIASES OF
PAGE REGISTER
6 Page DS1495/DS1497
ABSOLUTE MAXIMUM RATINGS*
VDD Pin Potential to Ground Pin
Input Voltage
Power Dissipation
Storage Temperature
Ambient Temperature
Soldering Temperature
-0.3V to +7.0V
VSS – 0.3 to VDD + 0.3V
500 mW
DS1497: –40°C to +70°C
DS1495: –55°C to +125°C
0°C to 70°C
260°C for 10 seconds
* This is a stress rating only and functional operation of the device at these or any other conditions above those
indicated in the operation sections of this specification is not implied. Exposure to absolute maximum rating
conditions for extended periods of time may affect reliability.
RECOMMENDED DC OPERATING CONDITIONS
CHARACTERISTIC
TEST CONDITION
www.DataSheet4U.comSupply Voltage
Input High Voltage
Input Low Voltage
Battery Voltage
Recognized as a High Signal Over
Recommended VDD and tA Range
Recognized as a Low Signal Over
Recommended VDD and tA Range
(0°C to 70°C)
SYM MIN MAX UNITS NOTES
VCC 4.5
5.5
V
VIH 2.2 VDD+ V
0.3 V
VIL -0.3 0.8
V
VBAT 2.5
3.7
V
DC ELECTRICAL CHARACTERISTICS
(VDD = 5.0V + 10%, VSS = 0V, tA = 0° C to 70°C)
CHARACTERISTIC
TEST CONDITION
SYM MIN MAX UNIT NOTES
Input Leakage
VIL=0V, VIH=VDD
For any Single Pin: D0-7, RD, WR,
A0-5, XRAM, RTC, RESET
II
+1 µA
Output High Voltage VDD=5.0V ILOAD =1 mA
VOH
2.4
V
Output Low Voltage
VDD = 5.0V ILOAD = 2 mA
VOL 0.4 V
Power Supply Current
STBY pin Input Current
STBY pin Input Current
Outputs Unloaded
STBY=VDD
STBY=VSS
IDD
ISTBY
ISTBY
50
+500
–1
mA
µA
µA
AC SWITCHING CHARACTERISTICS
CHARACTERISTIC
TEST CONDITION
Reset Pulse Width
Oscillator Startup
From Software Enable Via DV Bits
IRQ Release from RD
High
IRQ Release from
RESET Low
(0°C to 70°C; VDD = 4.5V to 5.5V)
SYM MIN MAX UNIT NOTES
tRWL
5
µs
tRC
tIRDS
1s
2 µs
tIRR 2 µs
020894 12/19
12 Page | ||
Seiten | Gesamt 19 Seiten | |
PDF Download | [ DS1497 Schematic.PDF ] |
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