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DS1251P Schematic ( PDF Datasheet ) - Dallas Semiconducotr

Teilenummer DS1251P
Beschreibung 4096k NV SRAM with Phantom Clock
Hersteller Dallas Semiconducotr
Logo Dallas Semiconducotr Logo 




Gesamt 22 Seiten
DS1251P Datasheet, Funktion
www.DataSheet4U.com
DS1251/DS1251P
4096k NV SRAM with Phantom Clock
www.maxim-ic.com
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
§ Embedded lithium energy cell maintains
A18/RST
A16
A14
A12
A7
A6
A5
1
2
3
4
5
6
7
32 VCC
31 A15
30 A17
29 WE
28 A13
27 A8
26 A9
calendar operation and retains RAM data
§ Watch function is transparent to RAM
operation
§ Month and year determine the number of
A4 8
A3 9
A2 10
A1 11
A0 12
25 A11
24 OE
23 A10
22 CE
21 DQ7
days in each month; valid up to 2100
DQ0 13
20 DQ6
§ Over 10 years of data retention in the
absence of power
§ Full 10% operating range
DQ1
DQ2
GND
14
15
16
19 DQ5
18 DQ4
17 DQ3
§ Lithium energy source is electrically
disconnected to retain freshness until power
is applied for the first time
DataSheet4U.com
32-Pin Encapsulated Package
740mil Flush
§ DIP Module only
– Standard 32-pin JEDEC pinout
– Upward comparable with the DS1248
§ PowerCap® Module Board only
– Surface mountable package for direct
connection to PowerCap containing
battery and crystal
– Replaceable battery (PowerCap)
– Pin for pin compatible with other densities
of DS124XP phantom clocks
RST
A15
A16
NC
VCC
WE
OE
CE
DQ7
DQ6
DQ5
DQ4
DQ3
DQ2
DQ1
DQ0
GND
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
X1 GND VBAT X2
34
33
32
31
30
29
28
27
26
25
24
23
22
21
20
19
18
34-Pin PowerCap Module Board
(Uses DS9034PCX PowerCap)
A18
A17
A14
A13
A12
A11
A10
A9
A8
A7
A6
A5
A4
A3
A2
A1
A0
DataShee
PowerCap is a registered trademark of Dallas Semiconductor.
DataSheet4U.com
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DS1251P Datasheet, Funktion
www.DataSheet4U.com
PHANTOM CLOCK REGISTER DEFINITION Figure 2
DS1251/DS1251P
et4U.com
DataSheet4U.com
DataShee
AM/PM/12/24 MODE
Bit 7 of the hours register is defined as the 12-hour or 24-hour mode-select bit. When high, the 12-hour
mode is selected. In the 12-hour mode, bit 5 is the AM/PM bit with logic high being PM. In the 24-hour
mode, bit 5 is the second 10-hour bit (20–23 hours).
OSCILLATOR AND RESET BITS
Bits 4 and 5 of the day register are used to control the RESET and oscillator functions. Bit 4 controls the
RESET (pin 1). When the RESET bit is set to logic 1, the RESET input pin is ignored. When the RESET
bit is set to logic 0, a low input on the RESET pin will cause the phantom clock to abort data transfer
without changing data in the watch registers. Bit 5 controls the oscillator. When set to logic 1, the
oscillator is off. When set to logic 0, the oscillator turns on and the watch becomes operational. These bits
are shipped from the factory set to a logic 1.
ZERO BITS
Registers 1, 2, 3, 4, 5, and 6 contain one or more bits which will always read logic 0. When writing these
locations, either a logic 1 or 0 is acceptable.
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6 Page









DS1251P pdf, datenblatt
www.DataSheet4U.com
DS1251/DS1251P
MEMORY AC ELECTRICAL CHARACTERISTICS
Over the operating range (3.3V)
PARAMETER
SYMBOL
DS1251W-120
MIN MAX
UNITS
NOTES
Read Cycle Time
Access Time
tRC 120
ns
tACC 120 ns
OE to Output Valid
tOE 60 ns
CE to Output Valid
tCO 120 ns
OE or CE to Output Active
tCOE
5
ns 5
Output High-Z from Deselection
Output Hold from Address Change
Write Cycle Time
Write Pulse Width
Address Setup Time
Write Recovery Time
tOD
40 ns
5
tOH 5
ns
tWC 120
ns
tWP 90
ns 3
tAW 0
ns
tWR 20
ns 10
Output High-Z from WE
tODW
40 ns
5
Output Active from WE
tOEW
5
ns 5
Data Setup Time
tDS 50
ns 4
Data Hold Time from WE
tDH 20
ns 4
et4U.com
PHANTOM
CLOCK
AC
ELECTRICAL
CHARACTERISTICS
Over the operating
range
(3.3V)
PARAMETER
SYDMataBSOheLet4UM.coINm TYP MAX UNITS NOTES
Read Cycle Time
tRC 120
ns
CE Access Time
tCO 100 ns
OE Access Time
tOE 100 ns
CE to Output Low-Z
tCOE
5
ns
OE to Output Low-Z
tOEE
5
ns
CE to Output High-Z
tOD
40 ns
5
OE to Output High-Z
tODO
40 ns
5
Read Recovery
Write Cycle Time
Write Pulse Width
Write Recovery
Data Setup Time
Data Hold Time
tRR 20
tWC 120
tWP 100
tWR 20
tDS 45
tDH 0
ns
ns
ns 3
ns 10
ns 4
ns 4
CE Pulse Width
tCW 105
ns
RESET Pulse Width
tRST 120
ns
DataShee
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