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PDF DS1251Y Data sheet ( Hoja de datos )
| Número de pieza | DS1251Y | |
| Descripción | 4096K NV SRAM with Phantom Clock | |
| Fabricantes | Dallas Semiconducotr | |
| Logotipo |  |
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DS1251Y
DS1251Y
4096K NV SRAM with Phantom Clock
FEATURES
PIN ASSIGNMENT
• Real time clock keeps track of hundredths of seconds,
minutes, hours, days, date of the month, months, and
years
• 512K x 8 NV SRAM directly replaces volatile static
RAM or EEPROM
A18/RST
A16
A14
A12
A7
1
2
3
4
5
32 VCC
31 A15
30 A17
29 WE
28 A13
• Embedded lithium energy cell maintains calendar op-
eration and retains RAM data
• Watch function is transparent to RAM operation
A6 6
A5 7
A4 8
A3 9
27 A8
26 A9
25 A11
24 OE
• Month and year determine the number of days in each
month; valid up to 2100
• Standard 32–pin JEDEC pinout
A2
A1
A0
DQ0
10
11
12
13
23 A10
22 CE
21 DQ7
20 DQ6
• Full 10% operating range
DQ1
DQ2
• Operating temperature range 0°C to 70°C DataSheet4U.com GND
14
15
16
19 DQ5
18 DQ4
17 DQ3
• Accuracy is better than ±1 minute/month @ 25°C
32–PIN ENCAPSULATED PACKAGE
740 MIL FLUSH
• Over 10 years of data retention in the absence of
power
PIN DESCRIPTION
• Available in 120 ns and 150 ns access time
ORDERING INFORMATION
DS1251Y–120 120 ns access
DS1251Y–150 150 ns access
A0–A18
CE
GND
DQ0–DQ7
VCC
WE
OE
RST
– Address Inputs
– Chip Enable
– Ground
– Data In/Data Out
– Power (+5V)
– Write Enable
– Output Enable
– Reset
DataShee
DESCRIPTION
The DS1251Y 4096K NV SRAM with Phantom Clock is
a fully static nonvolatile RAM (organized as 512K words
by 8 bits) with a built–in real time clock. The DS1251Y
has a self–contained lithium energy source and control
circuitry which constantly monitors VCC for an out–of–
tolerance condition. When such a condition occurs, the
lithium energy source is automatically switched on and
write protection is unconditionally enabled to prevent
garbled data in both the memory and real time clock.
DataSheet4U.com
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 less 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.
ECopyright 1997 by Dallas Semiconductor Corporation.
All Rights Reserved. For important information regarding
DataSheet 4 U .compatents and other intellectual property rights, please refer to
Dallas Semiconductor data books.
032697 1/12
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DS1251Y
ABSOLUTE MAXIMUM RATINGS*
Voltage on Any Pin Relative to Ground
Operating Temperature
Storage Temperature
Soldering Temperature
–0.3V to +7.0V
0°C to 70°C
–40°C to +70°C
260°C for 10 seconds (See Note 13)
* 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
PARAMETER
SYMBOL MIN
Power Supply Voltage
Input Logic 1
Input Logic 0
VCC 4.5
VIH 2.2
VIL –0.3
TYP
5.0
DC ELECTRICAL CHARACTERISTICS
PARAMETER
SYMBOL
MIN
TYP
Input Leakage Current
I/O Leakage Current
CE VIH VCC
Output Current @ 2.4 volts
et4U.Ocoutmput Current @ 0.4 volts
Standby Current CE = 2.2 volts
Standby Current CE =
VCC – 0.5 volts
Operating Current tCYC = 200 ns
IIL –1.0
IIO –1.0
IOHDataSh–e1e.0t4U.com
IOL 2.0
ICCS1
5.0
ICCS2
3.0
ICC01
DC TEST CONDITIONS
Outputs are open; all voltages are referenced to ground.
CAPACITANCE
PARAMETER
Input Capacitance
Input/Output Capacitance
SYMBOL
CIN
CI/O
MIN
TYP
5
5
MAX
5.5
VCC+0.3
+0.8
(0°C to 70°C)
UNITS NOTES
V
V
V
(0°C to 70°C; VCC = 5V ± 10%)
MAX
UNITS NOTES
+1.0 µA
12
+1.0 µA
mA
mA DataShee
10 mA
5.0 mA
85 mA
MAX
10
10
UNITS
pF
pF
(tA = 25°C)
NOTES
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032697 5/12
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DS1251Y
NOTES:
1. WE is high for a read cycle.
2. OE = VIH or VIL. If OE = VIH during write cycle, the output buffers remain in a high impedance state.
3. tWP is specified as the logical AND of CE and WE. tWP is measured from the latter of CE or WE going low to the
earlier of CE or WE going high.
4. tDH, tDS are measured from the earlier of CE or WE going high.
5. These parameters are sampled with a 50 pF load and are not 100% tested.
6. If the CE low transition occurs simultaneously with or later than the WE low transition in Write Cycle 1, the output
buffers remain in a high impedance state during this period.
7. If the CE high transition occurs prior to or simultaneously with the WE high transition, the output buffers remain
in a high impedance state during this period.
8. If WE is low or the WE low transition occurs prior to or simultaneously with the CE low transition, the output buffers
remain in a high impedance state during this period.
9. The expected tDR is defined as accumulative time in the absence of VCC with the clock oscillator running.
10. tWR is a function of the latter occurring edge of WE or CE.
11. tDH and tDS are a function of the first occurring edge of WE or CE.
12. RST (Pin1) has an internal pull–up resistor.
13. Real–Time Clock Modules can be successfully processed through conventional wave–soldering techniques as
long as temperature exposure to the lithium energy source contained within does not exceed +85°C. Post solder
cleaning with water washing techniques iDs aactcaeSpthaebleet,4pUro.vcidoemd that ultrasonic vibration is not used.
et4U.com
DataShee
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032697 11/12
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| Páginas | Total 12 Páginas | |
| PDF Descargar | [ Datasheet DS1251Y.PDF ] | |
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