dallas semiconductor DS1345Y, DS1345AB service manual

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DS1345Y/AB

1024k Nonvolatile SRAM

with Battery Monito

FEATURES

 10 years minimum data retention in the

absence of external power



Data is automatically protected during power loss

 Power supply monitor resets processor when

VCC power loss occurs and holds processor in
reset during VCC ramp-up

 Battery monitor checks remaining capacity

daily

 Read and write access times as fast as 70 ns
 Unlimited write cycle endurance
 Typical standby current 50 µA
 Upgrade for 128k x 8 SRAM, EEPROM or

Flash

 Lithium battery is electrically disconnected to

retain freshness until power is applied for the
first time

 Full ±10% VCC operating range (DS1345Y)

or optional ±5% VCC operating range
(DS1345AB)

 Optional industrial temperature range of

-40°C to +85°C, designated IND

 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

BW
A15
A16

RST

V

WE

OE

CE
DQ7
DQ6
DQ5
DQ4
DQ3

DQ2
DQ1
DQ0

GND

1
2
3
4

CC

5
6

7
8
9
10
11
12
13
14
15
16
17

34-Pin POWERCAP MODULE (PCM)

(USES DS9034PC POWERCAP)

GND

V

BAT

34
33
32
31
30
29
28
27
26
25
24
23
22
21
20
19
18

NC
NC

14
13
12

6
5

3
2

0

PIN DESCRIPTION

A0 - A16 - Address Inputs
DQ0 - DQ7 - Data In/Data Out

CE - Chip Enable
WE - Write Enable
OE - Output Enable
RST - Reset Output
BW - Battery Warning Output

- Power (+5V)

V

CC

GND - Ground
NC - No Connect

DESCRIPTION

The DS1345 1024k Nonvolatile SRAMs are 1,048,576-bit, fully static, nonvolatile SRAMs 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
lithium energy source is automatically switched on and write protection is unconditionally enabled to
prevent data corruption. Additionally, the DS1345 devices have dedicated circuitry for monitoring the
status of VCC and the status of the internal lithium battery. DS1345 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. The devices can be used in place of 128k x 8 SRAM, EEPROM or
Flash components.

for an out-of-tolerance condition. When such a condition occurs, the

CC

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DS1345Y/AB

READ MODE

The DS1345 devices execute 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 17 address inputs

(A0 - A16) 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

(Access Time) after the last address input signal is stable, providin g

ACC

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 tCO for CE or tOE for OE rather than address access.

WRITE MODE

The DS1345 devices execute a write c ycle whenever the WE and CE signals are i n the active (low) state
after address inputs are stable. The later-occurrin g 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 (tWR) 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

from its falling edge.

ODW

DATA RETENTION MODE

The DS1345AB provides full functional capability for VCC greater than 4.75 volts and write protects by

4.5 volts. The DS1345Y provides full functional capability for VCC greater than 4.5 volts and write
protects by 4.25 volts. Data is maintained in the absence of VCC without any additional support circuitry.
The nonvolatile static RAMs constantly monitor VCC. 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 VCC falls below approximately 2.7 volts, the power switching circuit connects the lithium
energy source to RAM to retain data. During power-up, when VCC rises above approximately 2.7 volts,
the power switching circuit connects external VCC to the RAM and disconnects the lithium energy source.
Normal RAM operation can resume after VCC exceeds 4.75 volts for the DS1345AB and 4.5 volts for the
DS1345Y.

SYSTEM POWER MONITORING

DS1345 devices have the ability to monitor the external VCC power supply. When an out-of-tolerance
power supply condition is detected, the NV SRAMs warn a processor-based system of impending power

failure by asserting RST . On power-up, RST is held active for 200 ms nominal to prevent system
operation during power-on transients and to allow t

to elapse. RST has an open drain output driver.

REC

BATTERY MONITORING

The DS1345 devices automatically perform periodic battery voltage monitoring on a 24-hour time
interval. Such monitoring begins within t
failure occurs.

After each 24-hour period has elapsed, the battery is connected to an internal 1 MΩ=test resistor for one
second. During this one second, if battery voltage falls below the battery voltage trip point (2.6V), the

battery warning output

BW is asserted. Once asserted, BW remains active until the module is replaced.

The battery is still retested after each VCC power-up, however, even if BW is active. If the battery voltage
is found to be higher than 2.6V during such testing, BW is de-asserted and regular 24-hour testing
resumes. BW has an open drain output driver.

after VCC rises above VTP and is suspended when power

REC

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DS1345Y/AB

FRESHNESS SEAL

Each DS1345 is shipped from Dallas Semiconductor with its lithium energy source disconnected,
guaranteeing full energy capacity. When VCC is first applied at a level greater than VTP, the lithium
energy source is enabled for battery backup operation.

PACKAGES

The 34-pin PowerCap Module integrates SRAM memory and nonvolatile control along with contacts for
connection to the lithium battery in the DS9034PC PowerCap. The PowerCap Module pack age design
allows a DS1345 PCM device to be surface mounted without subjecting its lithium backup battery to
destructive high-temperature reflow soldering. After a DS1345 PCM is reflow soldered, a DS9034PC is
snapped on top of the PCM to form a complete Nonvolatile SRAM module. The DS9034PC is keyed to
prevent improper attachment. DS1345 PowerCap Modules and DS9034PC PowerCaps are ordered
separately and shipped in separate containers. See the DS9034PC data sheet for further information.

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DS1345Y/AB

ABSOLUTE MAXIMUM RATINGS*

Voltage on Any Pin Relative to Ground -0.3V to +7.0V
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 (tA: See Note 10)

PARAMETER SYMBOL MIN TYP MAX UNITS NOTES

DS1345AB Power Supply Voltage V
DS1345Y Power Supply Voltage V
Logic 1 V
Logic 0 V

CC

CC

IH

IL

4.75 5.0 5.25 V

4.5 5.0 5.5 V

2.2 V

CC

V

0.0 0.8 V

DC ELECTRICAL (VCC=5V ±=5% for DS1345AB)
CHARACTERISTICS (t

PARAMETER SYMBOL MIN TYP MAX UNITS NOTES

Input Leakage Current I
I/O Leakage Current CE ≥ VIH ≤ V

Output Current @ 2.4V I
Output Current @ 0.4V I
Standby Current CE =2.2V

Standby Current CE =VCC-0.5V
Operating Current I
Write Protection Voltage (DS1345AB) V
Write Protection Voltage (DS1345Y) V

CC

: See Note 10) (VCC=5V ±=10% for DS1345Y)

A

I

OH

OL

I

CCS1

I

CCS2

CCO1

IL

IO

TP

TP

-1.0 +1.0

-1.0 +1.0

-1.0 mA 14

2.0 mA 14
200 600

50 150

85 mA

4.50 4.62 4.75 V

4.25 4.37 4.5 V

µA
µA

µA
µA

CAPACITANCE (tA=25°C)

PARAMETER SYMBOL MIN TYP MAX UNITS NOTES

Input Capacitance C
Input/Output Capacitance C

IN

I/O

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510pF
510pF