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What is DS1647P?

This electronic component, produced by the manufacturer "Dallas Semiconducotr", performs the same function as "Nonvolatile Timekeeping RAM".


DS1647P Datasheet PDF - Dallas Semiconducotr

Part Number DS1647P
Description Nonvolatile Timekeeping RAM
Manufacturers Dallas Semiconducotr 
Logo Dallas Semiconducotr Logo 


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DS1647/DS1647P
Nonvolatile Timekeeping RAM
www.maxim-ic.com
FEATURES
§ Integrates NV SRAM, real-time clock,
crystal, power-fail control circuit and lithium
energy source
§ Clock registers are accessed identically to the
static RAM. These registers are resident in
the eight top RAM locations
§ Totally nonvolatile with over 10 years of
operation in the absence of power
§ BCD coded year, month, date, day, hours,
minutes, and seconds with leap year
compensation valid up to 2100
§ Power-fail write protection allows for ±10%
VCC power supply tolerance
§ DS1647 only (DIP Module)
- Standard JEDEC byte-wide 128k x 8
RAM pinout
§ DS1647P only (PowerCap® Module Board)
- Surface mountable package for direct
connection to PowerCap containing
battery and crystal
- Replaceable battery (PowerCap)
- Power-fail output
- Pin-for-pin compatible with other
densities of DS164XP Timekeeping
RAM
ORDERING INFORMATION
DS1647
32-pin DIP module
*DS1647P
34-pin PowerCap Module
Board
*DS9034PCX
PowerCap (Required; must
be ordered separately)
PIN ASSIGNMENT
A18
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 A17
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
NC
A15
A16
PFO
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
X1 GND VBAT
X2
17
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
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DS1647P equivalent
RETRIEVING DATA FROM RAM OR CLOCK
DS1647/DS1647P
The DS1647 is in the read mode whenever WE (write enable) is high; CE (chip enable) is low. The
device architecture allows ripple-through access to any of the address locations in the NV SRAM. Valid
data will be available at the DQ pins within tAA after the last address input is stable, providing that the CE
and OE access times and states are satisfied. If CE or OE access times are not met, valid data will be
available at the latter of chip-enable access (tCEA) or at output enable access time (tOEA). The state of the
data input/output pins (DQ) is controlled by CE and OE . If the outputs are activated before tAA, the data
lines are driven to an intermediate state until tAA. If the address inputs are changed while CE and OE
remain valid, output data will remain valid for output data hold time (tOH) but will then go indeterminate
until the next address access.
WRITING DATA TO RAM OR CLOCK
The DS1647 is in the write mode whenever WE and CE are in their active state. The start of a write is
referenced to the latter occurring high to low transition of WE and CE . The addresses must be held valid
throughout the cycle. CE or WE must return inactive for a minimum of tWR prior to the initiation of
another read or write cycle. Data in must be valid tDS prior to the end of write and remain valid for tDH
afterward. In a typical application, the OE signal will be high during a write cycle. However, OE can be
active provided that care is taken with the data bus to avoid bus contention. If OE is low prior to WE
transitioning low the data bus can become active with read data defined by the address inputs. A low
transition on WE will then disable the outputs tWEZ after WE goes active.
DATA RETENTION MODE
When VCC is within nominal limits (VCC > 4.5 volts) the DS1647 can be accessed as described above with
read or write cycles. However, when VCC is below the power-fail point VPF (point at which write
protection occurs) the internal clock registers and RAM are blocked from access. This is accomplished
internally by inhibiting access via the CE signal. At this time the power-fail output signal ( PFO ) will be
driven active low and will remain active until VCC returns to nominal levels. When VCC falls below the
level of the internal battery supply, power input is switched from the VCC pin to the internal battery and
clock activity, RAM, and clock data are maintained from the battery until VCC is returned to nominal
level.
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Part Details

On this page, you can learn information such as the schematic, equivalent, pinout, replacement, circuit, and manual for DS1647P electronic component.


Information Total 11 Pages
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