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PDF DS1284 Data sheet ( Hoja de datos )
| Número de pieza | DS1284 | |
| Descripción | (DS1284 / DS1286) Watchdog Timekeepers | |
| Fabricantes | Dallas Semiconductor | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de DS1284 (archivo pdf) en la parte inferior de esta página. Total 18 Páginas | ||
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DS1284/DS1286
Watchdog Timekeepers
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GENERAL DESCRIPTION
The DS1284/DS1286 watchdog timekeepers are
self-contained real-time clocks, alarms, watchdog
timers, and interval timers in a 28-pin JEDEC DIP
and encapsulated DIP package. The DS1286
contains an embedded lithium energy source and a
www.DataShqeueat4rUtz.cocmrystal, which eliminates the need for any
external circuitry. The DS1284 requires an external
quartz crystal and a VBAT source, which could be a
lithium battery. Data contained within 64 8-bit
registers can be read or written in the same manner
as byte-wide static RAM. Data is maintained in the
watchdog timekeeper by intelligent control circuitry
that detects the status of VCC and write protects
memory when VCC is out of tolerance. The lithium
energy source can maintain data and real time for
over 10 years in the absence of VCC. Watchdog
timekeeper information includes hundredths of
seconds, seconds, minutes, hours, day, date, month,
and year. The date at the end of the month is
automatically adjusted for months with fewer than
31 days, including correction for leap year. The
DS1284/DS1286 operate in either 24-hour or 12-
hour format with an AM/PM indicator. The devices
provide alarm windows and interval timing between
0.01 seconds and 99.99 seconds. The real-time
alarm provides for preset times of up to one week.
FEATURES
Keeps Track of Hundredths of Seconds,
Seconds, Minutes, Hours, Days, Date of the
Month, Months, and Years; Valid Leap Year
Compensation Up to 2100
Watchdog Timer Restarts an Out-of-Control
Processor
Alarm Function Schedules Real-Time-Related
Activities
Embedded Lithium Energy Cell Maintains
Time, Watchdog, User RAM, and Alarm
Information
Programmable Interrupts and Square-Wave
Outputs Maintain JEDEC Footprint
All Registers are Individually Addressable via
the Address and Data Bus
Accuracy is Better than ±1 Minute/Month at
+25°C (EDIP)
Greater than 10 Years of Timekeeping in the
Absence of VCC
50 Bytes of User NV RAM
Underwriters Laboratory (UL) Recognized
-40°C to +85°C Industrial Temperature Range
Option
Pin Configurations appear at end of data sheet.
ORDERING INFORMATION
PART
TEMP RANGE VOLTAGE (V)
DS1284
0°C to +70°C
5.0
DS1284N
-40°C to +85°C
5.0
DS1284Q
0°C to +70°C
5.0
DS1284Q+
0°C to +70°C
5.0
DS1284Q/T&R
0°C to +70°C
5.0
DS1284Q+T&R
0°C to +70°C
5.0
DS1284QN
-40°C to +85°C
5.0
DS1284QN+
-40°C to +85°C
5.0
DS1284QN/T&R
-40°C to +85°C
5.0
DS1284QN+T&R
-40°C to +85°C
5.0
DS1286
0°C to +70°C
5.0
DS1286I
-40°C to +85°C
5.0
DS1286I+
-40°C to +85°C
5.0
+ Denotes a lead-free/RoHS-compliant package.
* A “+” anywhere on the top mark indicates a lead-free package.
PIN-PACKAGE
28 DIP (600 mils)
28 DIP (600 mils)
28 PLCC
28 PLCC
28 PLCC/Tape and Reel
28 PLCC/Tape and Reel
28 PLCC
28 PLCC
28 PLCC/Tape and Reel
28 PLCC/Tape and Reel
28 EDIP (720 mils)
28 EDIP (720 mils)
28 EDIP (720 mils)
TOP MARK*
DS1284
DS1284 N
DS1284Q
DS1284Q
DS1284Q
DS1284Q
DS1284QN
DS1284QN
DS1284QN
DS1284QN
DS1286
DS1286 IND
DS1286 IND
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REV: 032406
1 page  
DS1284/DS1286
HUNDREDTHS-OF-SECONDS GENERATOR
The hundredths-of-seconds generator circuit shown in the Block Diagram (Figure 1) is a state machine
that divides the incoming frequency (4096Hz) by 41 for 24 cycles and 40 for 1 cycle. This produces a
100Hz output that is slightly off during the short term, and is exactly correct every 250ms. The divide
ratio is given by:
Ratio = [41 x 24 + 40 x 1] / 25 = 40.96
Thus, the long-term average frequency output is exactly 100Hz.
Figure 2. Watchdog Timekeeper Registers
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5 of 18
5 Page 
READ CYCLE (NOTE 1)
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WRITE CYCLE 1 (NOTES 2, 6, 7)
DS1284/DS1286
11 of 18
11 Page | ||
| Páginas | Total 18 Páginas | |
| PDF Descargar | [ Datasheet DS1284.PDF ] | |
Hoja de datos destacado
| Número de pieza | Descripción | Fabricantes |
| DS1283 | Watchdog Timekeeper Chip | Dallas Semiconductor |
| DS1284 | (DS1284 / DS1286) Watchdog Timekeepers | Dallas Semiconductor |
| DS1284 | (DS1284 / DS1286) Watchdog Timekeepers | Dallas Semiconductor |
| DS1284 | (DS1284 / DS1286) Watchdog Timekeepers | Dallas Semiconductor |
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