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111899

FEATURES

10 years minimum data retention in the
absence of external power

Data is automatically protected during power
loss

Replaces 128k x 8 volatile static RAM,
EEPROM or Flash memory

Unlimited write cycles

Low-power CMOS

Read and write access times as fast as 150 ns

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 32-pin DIP package

New 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

PIN DESCRIPTION

A0 - A16

- Address Inputs

DQ0 - DQ7

- Data In/Data Out

- Chip Enable

- Write Enable

- Output Enable

- Power (+3.3V)

GND -

Ground

- No Connect

DS1245W

3.3V 1024k Nonvolatile SRAM

www.dalsemi.com

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32-PIN ENCAPSULATED PACKAGE

740-MIL EXTENDED

A14

A5
A4
A3
A2
A1
A0

DQ1

DQ0

A15
NC
WE
A13
A8
A9
A11
OE
A10
CE
DQ7

DQ5

DQ6

30
29
28
27
26
25
24
23
22
21

A16

A12

DQ2

GND

15
16

18
17

DQ4
DQ3

A15

A16

DQ7

DQ6

DQ5

DQ4

DQ3

DQ2

DQ1

DQ0

GND

A14

A13

A12

A11

A10

GND V

BAT

34-PIN POWERCAP MODULE (PCM)

(USES DS9034PC POWERCAP)

DS1245W

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DESCRIPTION

The DS1245W 3.3V 1024k Nonvolatile SRAM is a 1,048,576-bit, fully static, nonvolatile SRAM
organized as 131,072 words by 8 bits. Each NV SRAM has a self-contained lithium energy source and
control circuitry which constantly monitors V

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 DS1245W devices can be used in place of existing 128k
x 8 static RAMs directly conforming to the popular bytewide 32-pin DIP standard. DS1245W 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 DS1245W executes a read cycle whenever

(Write Enable) is inactive (high) and

(Chip

Enable) and

(Output Enable) are active (low). The unique address specified by the 17 address inputs

- A

) defines which of the 131,072 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

and

(Output Enable) access times are also satisfied. If

and

access times are not

satisfied, then data access must be measured from the later occurring signal (

) and the limiting

parameter is either t

for

or t

for

rather than address access.

WRITE MODE

The DS1245W executes a write cycle whenever the

and

signals are active (low) after address

inputs are stable. The later occurring falling edge of

will determine the start of the write cycle.

The write cycle is terminated by the earlier rising edge of

. All address inputs must be kept

valid throughout the write cycle.

must return to the high state for a minimum recovery time (t

)

before another cycle can be initiated. The

control signal should be kept inactive (high) during write

cycles to avoid bus contention. However, if the output drivers are enabled (

and

active) then

will disable the outputs in t

ODW

from its falling edge.

DATA RETENTION MODE

The DS1245W provides full functional capability for V

greater than 3.0 volts and write protects by 2.8

volts. Data is maintained in the absence of V

without any additional support circuitry. The nonvolatile

static RAMs constantly monitor V

. 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

falls below approximately 3.0 volts, a power switching circuit connects the lithium energy source to
RAM to retain data. During power-up, when V

rises above approximately 2.5 volts, the power

switching circuit connects external V

to RAM and disconnects the lithium energy source. Normal

RAM operation can resume after V

exceeds 3.0 volts.

FRESHNESS SEAL

Each DS1245W device is shipped from Dallas Semiconductor with its lithium energy source
disconnected, guaranteeing full energy capacity. When V

is first applied at a level greater than 3.0

volts, the lithium energy source is enabled for battery back-up operation.

PACKAGES

The DS1245W is available in two packages: 32-pin DIP and 34-pin PowerCap Module (PCM). The 32-
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

DS1245W

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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 DS1245W PCM
device to be surface mounted without subjecting its lithium backup battery to destructive high-
temperature reflow soldering. After a DS1245W 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. DS1245W 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

-0.3V to +4.6V

Operating Temperature

0°C to 70°C, -40°C to +85°C for Ind parts

Storage Temperature

-40°C to +70°C, -40°C to +85°C for Ind parts

Soldering Temperature

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 (t

: See Note 10)

PARAMETER

SYMBOL

MIN

TYP

MAX

UNITS NOTES

Power Supply Voltage

3.0

3.3

3.6

Logic 1

2.2

Logic 0

0.0

0.4

DC ELECTRICAL CHARACTERISTICS (t

: See Note 10) (V

=3.3V

0.3V)

PARAMETER

SYMBOL

MIN

TYP

MAX

UNITS NOTES

Input Leakage Current

-1.0

+1.0

I/O Leakage Current

-1.0

+1.0

Output Current @ 2.2V

-1.0

Output Current @ 0.4V

2.0

Standby Current

=2.2V

CCS1

250

Standby Current

-0.2V

CCS2

150

Operating Current

CCO1

Write Protection Voltage (DS1245AB)

2.8

2.9

3.0

CAPACITANCE (t

=25

PARAMETER

SYMBOL

MIN

TYP

MAX

UNITS NOTES

Input Capacitance

Input/Output Capacitance

I/O

DS1245W

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AC ELECTRICAL CHARACTERISTICS (t

: See Note 10) (V

=3.3V

0.3V)

DS1245W-150

PARAMETER

SYMBOL

MIN

MAX

TYPE

UNITS NOTES

Read Cycle Time

150

Access Time

ACC

150

to Output Valid

150

to Output Active

COE

Output High Z from Deselection

Output Hold from Address Change

Write Cycle Time

150

Write Pulse Width

100

Address Setup Time

Write Recovery Time

WR1

WR2

ns
ns

12
13

Output High Z from

ODW

Output Active from

OEW

Data Setup Time

Data Hold Time

DH1

DH2

ns
ns

12
13

READ CYCLE

DS1245W

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POWER-DOWN/POWER-UP TIMING (t

: See Note 10)

PARAMETER

SYMBOL

MIN

TYP

MAX

UNITS NOTES

Fail Detect to

and

Inactive

1.5

slew from V

to 0V

150

slew from 0V to V

150

Valid to

and

Inactive

Valid to End of Write Protection

REC

125

=25

PARAMETER

SYMBOL

MIN

TYP

MAX

UNITS NOTES

Expected Data Retention Time

years

WARNING:

Under no circumstance are negative undershoots, of any amplitude, allowed when device is in battery
backup mode.

NOTES:

is high for a Read Cycle.

= V

or V

. If

= V

during write cycle, the output buffers remain in a high impedance state.

is specified as the logical AND of

and

. t

is measured from the latter of

going low to the earlier of

going high.

, t

are measured from the earlier of

going high.

These parameters are sampled with a 5 pF load and are not 100% tested.

If the

low transition occurs simultaneously with or latter than the

low transition, the output

buffers remain in a high impedance state during this period.

If the

high transition occurs prior to or simultaneously with the

high transition, the output

buffers remain in high impedance state during this period.

is low or the

low transition occurs prior to or simultaneously with the

low transition,

the output buffers remain in a high impedance state during this period.

Each DS1245W has a built-in switch that disconnects the lithium source until V

is first applied by

the user. The expected t

is defined as accumulative time in the absence of V

starting from the

time power is first applied by the user.

10.

All AC and DC electrical characteristics are valid over the full operating temperature range. For
commercial products, this range is 0

C to 70

C. For industrial products (IND), this range is -40

C to

+85

11.

In a power-down condition the voltage on any pin may not exceed the voltage on V

12.

WR1

and t

DH1

are measured from

going high.

13.

WR2

and t

DH2

are measured from

going high.

DS1245W

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DC TEST CONDITIONS

AC TEST CONDITIONS

Outputs Open

Output Load: 100 pF + 1TTL Gate

Cycle = 200 ns for operating current

Input Pulse Levels: 0 - 3.0V

All voltages are referenced to ground

Timing Measurement Reference Levels

Input: 1.5V
Output: 1.5V

Input pulse Rise and Fall Times: 5 ns

ORDERING INFORMATION

DS1245 W P - SSS - III

Operating Temperature Range
blank: 0

to 70

IND: -40

to +85

Access Speed
150: 150 ns

Package Type
blank: 28-pin 600 mil DIP
P:

340-pin PowerCap Module

DS1245W NONVOLATILE SRAM, 32-PIN 740-MIL EXTENDED DIP MODULE

PKG

32-PIN

DIM

MIN

MAX

A IN.

1.680
42.67

1.700
43.18

B IN.

0.720
18.29

0.740
18.80

C IN.

0.355

9.02

0.375

9.52

D IN.

0.080

2.03

0.110

2.79

E IN.

0.015

0.38

0.025

0.63

F IN.

0.120

3.05

0.160

4.06

G IN.

0.090

2.29

0.110

2.79

H IN.

0.590
14.99

0.630
16.00

J IN.

0.008

0.20

0.012

0.30

K IN.

0.015

0.38

0.021

0.53

DS1245W

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DS1245W NONVOLATILE SRAM, 34-PIN POWERCAP MODULE WITH
POWERCAP

INCHES

PKG

DIM

MIN

NOM

MAX

0.920

0.925

0.930

0.955

0.960

0.965

0.240

0.245

0.250

0.052

0.055

0.058

0.048

0.050

0.052

0.015

0.020

0.025

0.020

0.025

0.030

ASSEMBLY AND USE

Reflow soldering
Dallas Semiconductor recommends that PowerCap Module bases experience one pass through solder
reflow oriented label-side up (live-bug).

Hand soldering and touch-up
Do not touch soldering iron to leads for more than 3 seconds. To solder, apply flux to the pad, heat the
lead frame pad and apply solder. To remove part, apply flux, heat pad until solder reflows, and use a
solder wick.

LPM replacement in a socket
To replace a Low Profile Module in a 68-pin PLCC socket, attach a DS9034PC PowerCap to a module
base then insert the complete module into the socket one row of leads at a time, pushing only on the
corners of the cap. Never apply force to the center of the device. To remove from a socket, use a PLCC
extraction tool and ensure that it does not hit or damage any of the module IC components. Do not use
any other tool for extraction.

Part Number DS1245W