DS1220Y
DS1220Y
16K Nonvolatile SRAM
FEATURES
PIN ASSIGNMENT
A7
A6
A5
A4
A3
A2
A1
A0
DQ0
DQ1
DQ2
GND
1
2
3
4
5
6
7
8
9
10
11
12
24
23
22
21
20
19
18
17
16
15
14
13
V
CC
A8
A9
WE
OE
A10
CE
DQ7
DQ6
DQ5
DQ4
DQ3
•
10 years minimum data retention in the absence of
external power
•
Data is automatically protected during power loss
•
Directly
replaces 2K x 8 volatile static RAM or
EEPROM
•
Unlimited write cycles
•
Low-power CMOS
•
JEDEC standard 24–pin DIP package
•
Read and write access times as fast as 100 ns
•
Full + 10% operating range
•
Optional
industrial temperature range of -40°C to
+85°C, designated IND
24–PIN ENCAPSULATED PACKAGE
720 MIL EXTENDED
PIN DESCRIPTION
A
0
-A
10
DQ
0
-DQ
7
CE
WE
OE
V
CC
GND
–
–
–
–
–
–
–
Address Inputs
Data In/Data Out
Chip Enable
Write Enable
Output Enable
Power (+5V)
Ground
DESCRIPTION
The DS1220Y 16K Nonvolatile SRAM is a 16,384-bit,
fully static, nonvolatile RAM organized as 2048 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 uncon-
ditionally enabled to prevent data corruption. The NV
SRAM can be used in place of existing 2K x 8 SRAMs
directly conforming to the popular bytewide 24-pin DIP
standard. The DS1220Y also matches the pinout of the
2716 EPROM or the 2816 EEPROM, allowing direct
substitution while enhancing performance. There is no
limit on the number of write cycles that can be executed
and no additional support circuitry is required for micro-
processor interfacing.
ECopyright
1995 by Dallas Semiconductor Corporation.
All Rights Reserved. For important information regarding
patents and other intellectual property rights, please refer to
Dallas Semiconductor data books.
091295 1/8
DS1220Y
READ MODE
The DS1220Y 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 11 address inputs (A
0
-A
10
)
defines which of the 2048 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
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.
recovery time (t
WR
) before another cycle can be initi-
ated. The OE control signal should be kept inactive
(high) during write cycles to avoid bus contention. How-
ever, if the output drivers are enabled (CE and OE ac-
tive) then WE will disable the outputs in t
ODW
from its
falling edge.
DATA RETENTION MODE
The DS1220Y provides full functional capability for V
CC
greater than 4.5 volts and write protects at 4.25 nominal.
Data is maintained in the absence of V
CC
without any
additional support circuitry. The DS1220Y constantly
monitors V
CC
. Should the supply voltage decay, the NV
SRAM automatically write protects itself, all inputs be-
come “don’t care,” and all outputs become high imped-
ance. As V
CC
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
CC
rises above approximately 3.0 volts, the power
switching circuit connects external V
CC
to RAM and dis-
connects the lithium energy source. Normal RAM oper-
ation can resume after V
CC
exceeds 4.5 volts.
WRITE MODE
The DS1220Y executes a write cycle whenever the WE
and CE signals are active (low) after address inputs are
stable. The latter 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
091295 2/8
DS1220Y
ABSOLUTE MAXIMUM RATINGS*
Voltage on Any Pin Relative to Ground
Operating Temperature
Storage Temperature
Soldering Temperature
-0.3V to +7.0V
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
Input Logic 1
Input Logic 0
SYMBOL
V
CC
V
IH
V
IL
MIN
4.5
2.2
0.0
TYP
5.0
MAX
5.5
V
CC
+0.8
UNITS
V
V
V
(0°C to 70°C)
NOTES
DC ELECTRICAL CHARACTERISTICS
PARAMETER
Input Leakage Current
I/O Leakage Current
CE > V
IH
< V
CC
Output Current @ 2.4V
Output Current @ 0.4V
Standby Current CE = 2.2V
Standby Current CE = V
CC
-0.5V
Operating Current t
CYC
=200ns
(Commercial)
Operating Current t
CYC
=200ns
(Industrial)
Write Protection Voltage
SYMBOL
I
IL
I
IO
I
OH
I
OL
I
CCS1
I
CCS2
I
CCO1
I
CCO1
V
TP
4.25
MIN
-1.0
-1.0
-1.0
2.0
3.0
2.0
TYP
(0°C to 70°C; V
CC
= 5V
±
10%)
MAX
+1.0
+1.0
UNITS
µA
µA
mA
mA
7.0
4.0
75
85
mA
mA
mA
mA
V
NOTES
CAPACITANCE
PARAMETER
Input Capacitance
Input/Output Capacitance
SYMBOL
C
IN
C
I/O
MIN
TYP
5
5
MAX
10
12
UNITS
pF
pF
(t
A
= 25°C)
NOTES
091295 3/8
DS1220Y
AC ELECTRICAL CHARACTERISTICS
DS1220Y-100
PARAMETER
Read Cycle Time
Access Time
OE to Output
Valid
CE to Output
Valid
OE or CE to
Output Active
Output High Z
from Deselection
Output Hold from
Address Change
Write Cycle Time
Write Pulse Width
Address Setup
Time
Write Recovery
Time
Output High Z
from WE
Output Active
from WE
Data Setup Time
Data Hold Time
SYM
t
RC
t
ACC
t
OE
t
CO
t
COE
t
OD
t
OH
t
WC
t
WP
t
AW
t
WR1
t
WR2
t
ODW
t
OEW
t
DS
t
DH1
t
DH2
5
40
0
10
5
100
75
0
0
10
35
5
50
0
10
5
35
5
120
90
0
0
10
35
5
60
0
10
MIN
100
100
50
100
5
35
5
150
100
0
0
10
35
MAX
DS1220Y-120
MIN
120
120
60
120
5
35
MAX
MIN
150
150
70
150
MAX
(0°C to 70°C; V
CC
=5.0V
±
10%)
DS1220Y-150
DS1220Y-200
MIN
200
200
100
200
5
35
5
200
150
0
0
10
35
5
80
0
10
MAX
UNITS
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
11
12
5
5
4
11
12
3
5
5
NOTE
091295 4/8
DS1220Y
READ CYCLE
ADDRESSES
V
IH
V
IL
V
IH
CE
V
IH
OE
V
IL
t
COE
t
COE
t
ACC
t
CO
V
IL
t
RC
V
IH
V
IL
V
IH
V
IH
V
IL
t
OH
t
OD
t
OE
V
IH
t
OD
V
OH
OUTPUT V
OH
V
OL
DATA VALID V
OL
D
OUT
SEE NOTE 1
WRITE CYCLE 1
ADDRESSES
V
IH
V
IL
t
AW
CE
t
WC
V
IH
V
IL
V
IH
V
IL
V
IL
t
WP
V
IL
t
WR1
V
IL
V
IH
t
OEW
WE
V
IH
t
ODW
V
IL
HIGH
INPEDANCE
t
DS
V
IH
D
OUT
t
DH1
V
IH
DATA IN
STABLE
V
IL
t
WC
V
IH
V
IL
t
AW
t
WP
V
IH
V
IL
V
IL
V
IL
V
IH
V
IH
WE
t
COE
D
OUT
V
IH
D
IN
DATA IN
STABLE
V
IL
V
IL
V
IL
V
IL
V
IH
V
IL
t
WR2
V
IH
V
IL
V
IL
D
IN
SEE NOTES 2, 3, 4, 6, 7 AND 8
WRITE CYCLE 2
ADDRESSES
CE
t
ODW
t
DS
t
DH2
V
IH
SEE NOTES 2, 3, 4, 6, 7 AND 8
091295 5/8
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