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DS1248 Schematic ( PDF Datasheet ) - Dallas Semiconducotr

Teilenummer DS1248
Beschreibung 1024k NV SRAM with Phantom Clock
Hersteller Dallas Semiconducotr
Logo Dallas Semiconducotr Logo 




Gesamt 21 Seiten
DS1248 Datasheet, Funktion
DS1248/DS1248P
1024k NV SRAM with Phantom Clock
www.maxim-ic.com
FEATURES
§ Real-time clock (RTC) keeps track of
hundredths of seconds, minutes, hours, days,
date of the month, months, and years
§ 128k x 8 NV SRAM directly replaces
volatile static RAM or EEPROM
§ Embedded lithium energy cell maintains
calendar operation and retains RAM data
§ Watch function is transparent to RAM
operation
§ Month and year determine the number of
days in each month; valid up to 2100
§ Full 10% operating range
§ Operating temperature range: 0°C to +70°C
§ Over 10 years of data retention in the
absence of power
§ Lithium energy source is electrically
disconnected to retain freshness until power
is applied for the first time
§ DIP Module only
§ Standard 32-pin JEDEC pinout
§ PowerCap® Module Board only
- Surface mountable package for direct
connection to PowerCap containing
battery and crystal
- Replaceable battery (PowerCap)
- Pin for pin compatible with DS1244P
and DS1251P
PIN ASSIGNMENT
RST
A16
A14
A12
A7
A6
A5
A4
A3
A2
A1
A0
DQ0
DQ1
DQ2
GND
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
32 VCC
31 A15
30 NC
29 WE
28 A13
27 A8
26 A9
25 A11
24 OE
23 A10
22 CE
21 DQ7
20 DQ6
19 DQ5
18 DQ4
17 DQ3
32-Pin Encapsulated Package
740mil Flush
RST
A15
A16
NC
VCC
WE
OE
CE
DQ7
DQ6
DQ5
DQ4
DQ3
DQ2
DQ1
DQ0
GND
1 34
2 33
3 32
4 31
5 30
6 29
7 28
8 27
9 26
10 25
11 24
12 23
13 22
14 21
15
16
X1 GND VBAT X2
20
19
17 18
34-Pin PowerCap Module Board
(Uses DS9034PCX PowerCap)
NC
NC
A14
A13
A12
A11
A10
A9
A8
A7
A6
A5
A4
A3
A2
A1
A0
PowerCap is a registered trademark of Dallas Semiconductor.
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DS1248 Datasheet, Funktion
PHANTOM CLOCK REGISTER DEFINITION Figure 2
DS1248/DS1248P
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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DS1248 pdf, datenblatt
POWER-DOWN/POWER-UP TIMING
PARAMETER
SYMBOL
CE at VIH before Power-Down
VCC Slew from VPF(MAX) to
tPD
tF
VPF(MIN)( CE at VIH)
VCC Slew from VPF(MAX) to
tR
VPF(MIN)( CE at VIH)
CE at VIH after Power-Up
tREC
DS1248/DS1248P
Over the operating range (3.3V)
MIN TYP MAX UNITS NOTES
0 ms
300 ms
0 ms
1.5 2.5 ms
PARAMETER
Expected Data Retention Time
SYMBOL MIN TYP
tDR 10
MAX
(TA = +25°C)
UNITS NOTES
years
9
Warning: Under no circumstances are negative undershoots, of any amplitude, allowed when device is
in battery-backup mode.
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