DS1230W
3.3V 256k Nonvolatile SRAM
www.maxim-ic.com
FEATURES
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10 years minimum data retention in the
absence of external power
Data is automatically protected during power
loss
Replaces 32k x 8 volatile static RAM,
EEPROM or Flash memory
Unlimited write cycles
Low-power CMOS
Read and write access times as fast as 100ns
Lithium energy source is electrically
disconnected to retain freshness until power is
applied for the first time
Optional industrial temperature range of
-40°C to +85°C, designated IND
JEDEC standard 28-pin DIP package
PowerCap Module (PCM) package
- Directly surface-mountable module
- Replaceable snap-on PowerCap provides
lithium backup battery
- Standardized pinout for all nonvolatile
SRAM products
- Detachment feature on PowerCap allows
easy removal using a regular screwdriver
PIN ASSIGNMENT
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
28
27
26
25
24
23
22
21
20
19
18
17
16
15
V
CC
WE
A13
A8
A9
A11
OE
A10
CE
DQ7
DQ6
DQ5
DQ4
DQ3
28-Pin Encapsulated Package
740-Mil Extended
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
34
33
32
31
30
29
28
27
26
25
24
23
22
21
20
19
18
NC
NC
A14
A13
A12
A11
A10
A9
A8
A7
A6
A5
A4
A3
A2
A1
A0
NC
NC
NC
NC
V
CC
WE
OE
CE
DQ7
DQ6
DQ5
DQ4
DQ3
DQ2
DQ1
DQ0
GND
GND V
BAT
34-Pin PowerCap Module (PCM)
(Uses DS9034PC PowerCap)
PIN DESCRIPTION
A0 - A14
DQ0 - DQ7
CE
WE
OE
V
CC
GND
NC
- Address Inputs
- Data In/Data Out
- Chip Enable
- Write Enable
- Output Enable
- Power (+3.3V)
- Ground
- No Connect
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103102
DS1230W
DESCRIPTION
The DS1230W 3.3V 256k Nonvolatile SRAM is a 262,144-bit, fully static, nonvolatile SRAM organized
as 32,768 words by 8 bits. Each NV SRAM has a self-contained lithium energy source and control
circuitry, which constantly monitors V
CC
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 data corruption. DIP-package DS1230W devices can be used in place of existing 32k x 8 static
RAMs directly conforming to the popular bytewide 28-pin DIP standard. The DIP devices also match the
pinout of 28256 EEPROMs, allowing direct substitution while enhancing performance. DS1230W
devices in the PowerCap Module package are directly surface mountable and are normally paired with a
DS9034PC PowerCap to form a complete Nonvolatile SRAM Module. There is no limit on the number of
write cycles that can be executed and no additional support circuitry is required for microprocessor
interfacing.
READ MODE
The DS1230W executes a read cycle whenever
WE
(Write Enable) is inactive (high) and
CE
(Chip
Enable) and
OE
(Output Enable) are active (low). The unique address specified by the 15 address inputs
(A
0
– A
14
) defines which of the 32,768 bytes of data is to be accessed. Valid data will be available to the
eight data output drivers within t
ACC
(Access Time) after the last address input signal is stable, providing
that
CE
and
OE
(Output Enable) access times are also satisfied. If
OE
and
CE
access times are not
satisfied, then data access must be measured from the later-occurring signal (
CE
or
OE
) and the limiting
parameter is either t
CO
for
CE
or t
OE
for
OE
rather than address access.
WRITE MODE
The DS1230W executes a write cycle whenever the
WE
and
CE
signals are active (low) after address
inputs are stable. The later-occurring falling edge of
CE
or
WE
will determine the start of the write cycle.
The write cycle is terminated by the earlier rising edge of
CE
or
WE
. All address inputs must be kept
valid throughout the write cycle.
WE
must return to the high state for a minimum recovery time (t
WR
)
before another cycle can be initiated. The
OE
control signal should be kept inactive (high) during write
cycles to avoid bus contention. However, if the output drivers are enabled (
CE
and
OE
active) then
WE
will disable the outputs in t
ODW
from its falling edge.
DATA RETENTION MODE
The DS1230W provides full functional capability for V
CC
greater than 3.0 volts and write protects by 2.8
volts. Data is maintained in the absence of V
CC
without any additional support circuitry. The nonvolatile
static RAMs constantly monitor V
CC
. Should the supply voltage decay, the NV SRAMs automatically
write protect themselves, all inputs become “don’t care,” and all outputs become high-impedance. As V
CC
falls below approximately 2.5 volts, a power switching circuit connects the lithium energy source to
RAM to retain data. During power-up, when V
CC
rises above approximately 2.5 volts, the power
switching circuit connects external V
CC
to RAM and disconnects the lithium energy source. Normal
RAM operation can resume after V
CC
exceeds 3.0 volts.
FRESHNESS SEAL
Each DS1230W device is shipped from Dallas Semiconductor with its lithium energy source
disconnected, guaranteeing full energy capacity. When V
CC
is first applied at a level greater than 3.0
volts, the lithium energy source is enabled for battery back-up operation.
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DS1230W
PACKAGES
The DS1230W is available in two packages: 28-pin DIP and 34-pin PowerCap Module (PCM). The 28-
pin DIP integrates a lithium battery, an SRAM memory and a nonvolatile control function into a single
package with a JEDEC-standard, 600-mil DIP pinout. The 34-pin PowerCap Module integrates SRAM
memory and nonvolatile control into a module base along with contacts for connection to the lithium
battery in the DS9034PC PowerCap. The PowerCap Module package design allows a DS1230W to be
surface mounted without subjecting its lithium backup battery to destructive high-temperature reflow
soldering. After a DS1230W module base is reflow soldered, a DS9034PC PowerCap is snapped on top
of the base to form a complete Nonvolatile SRAM module. The DS9034PC is keyed to prevent improper
attachment. DS1230W module bases and DS9034PC PowerCaps are ordered separately and shipped in
separate containers. See the DS9034PC data sheet for further information.
ABSOLUTE MAXIMUM RATINGS*
Voltage on Any Pin Relative to Ground
Operating Temperature
Storage Temperature
Soldering Temperature
*
-0.3V to +4.6V
0°C to 70°C, -40°C to +85°C for IND parts
-40°C to +70°C, -40°C to +85°C for IND parts
260°C for 10 seconds
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
Power Supply Voltage
Logic 1
Logic 0
SYMBOL
V
CC
V
IH
V
IL
MIN
3.0
2.2
0.0
TYP
3.3
MAX
3.6
V
CC
0.4
(t
A
: See Note 10)
UNITS
V
V
V
NOTES
DC ELECTRICAL CHARACTERISTICS
PARAMETER
Input Leakage Current
I/O Leakage Current
CE
³
V
IH
£
V
CC
Output Current @ 2.2V
Output Current @ 0.4V
Standby Current
CE
=2.2V
Standby Current
CE
=V
CC
-0.2V
Operating Current
Write Protection Voltage
SYMBOL
I
IL
I
IO
I
OH
I
OL
I
CCS1
I
CCS2
I
CCO1
V
TP
(t
A
: See Note 10) (V
CC
= 3.3V ± 0.3V)
MIN
-1.0
-1.0
-1.0
2.0
50
30
2.8
2.9
250
150
50
3.0
TYP
MAX
+1.0
+1.0
UNITS
mA
mA
mA
mA
mA
mA
mA
V
NOTES
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