Datasheet U631H64BSC45, U631H64BSC35, U631H64BSC25, U631H64SC25, U631H64BDK45 Datasheet (ZMD)

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Page 1
Features
p
High-performance CMOS non­volatile static RAM 8192 x 8 bits
p
25, 35 and 45 ns Access Times
p
p
Software STORE Initiation
(STORE Cycle Time < 10 ms)
p
Automatic STORE Timing
p
105 STORE cycles to EEPROM
p
10 years data retention in EEPROM
p
Automatic RECALL on Power Up
p
Software RECALL Initiation
(RECALL Cycle Time < 20 µs)
p
Unlimited RECALL cycles from EEPROM
p
Unlimited Read and Write to
SRAM
p
Single 5 V ± 10 % Operation
p
Operating temperature ranges:
p
CECC 90000 Quality Standard
p
ESD characterization according MIL STD 883C M3015.7-HBM (classification see IC Code Numbers)
0 to 70 °C
-40 to 85 °C
p
Packages:PDIP28 (300 mil)
SOP28 (330 mil)
Description
The U631H64 has two separate modes of operation: SRAM mode and nonvolatile mode. In SRAM mode, the memory operates as an ordinary static RAM. In nonvolatile operation, data is transferred in parallel from SRAM to EEPROM or from EEPROM to SRAM. In this mode SRAM functions are disab­led. The U631H64 is a fast static RAM (25, 35, 45 ns), with a nonvolatile electrically erasable PROM (EEPROM) element incorporated in each static memory cell. The SRAM can be read and written an unlimited number of times, while independent nonvolatile data resi­des in EEPROM. Data transfers from the SRAM to the EEPROM (the STORE operation), or from the EEPROM to the SRAM (the RECALL operation) are initiated through software sequences.
U631H64
SoftStore
The U631H64 combines the high performance and ease of use of a fast SRAM with nonvolatile data integrity. Once a STORE cycle is initiated, further input or output are disabled until the cycle is completed. Because a sequence of addresses is used for STORE initiation, it is important that no other read or write accesses intervene in the sequence or the sequence will be aborted. Internally, RECALL is a two step procedure. First, the SRAM data is cleared and second, the nonvolatile information is transferred into the SRAM cells. The RECALL operation in no way alters the data in the EEPROM cells. The nonvolatile data can be recalled an unlimited number of times.
8K x 8 nvSRAM
Pin Configuration Pin Description
PDIP
SOP
28
VCC
27
W
26
n.c.
25
A8
24
A9
23
A11
22
G
21
A10
20
E
19
DQ7
18
DQ6
17
DQ5
16
DQ4
15
DQ3
Signal Name Signal Description
A0 - A12 Address Inputs DQ0 - DQ7 Data In/Out E G W VCC Power Supply Voltage VSS Ground
1
1
n.c.
2
A12
3
A7
4
A6
5
A5
6
A4
7
A3
8
A2
9
A1
10
A0
11
DQ0
12
DQ1
13
DQ2
14
VSS
Top View
December 12, 1997
Chip Enable Output Enable Write Enable
Page 2
U631H64
Block Diagram
A5 A6 A7 A8 A9 A11 A12
DQ0 DQ1 DQ2 DQ3 DQ4 DQ5 DQ6
DQ7
64 x 8 Columns
Row Decoder
Column Decoder
Input Buffers
A0 A1 A2 A3 A4A10
EEPROM Array
Array
128 Rows x
Column I/O
128 x (64 x 8)
STORE
RECALLSRAM
Store/ Recall
Control
Software
Detect
Truth Table for SRAM Operations
Operating Mode E W G DQ0 - DQ7
Standby/not selected H
**
Internal Read L H H High-Z
Read L H L Data Outputs Low-Z Write L L
*
Data Inputs High-Z
*H or L
V V
V
G
E
W
High-Z
CC
SS
CC
A0 - A12
Characteristics
All voltages are referenced to VSS = 0 V (ground). All characteristics are valid in the power supply voltage range and in the operating temperature range specified. Dynamic measurements are based on a rise and fall time of 5 ns, measured between 10 % and 90 % of V input levels of V with the exception of the t
Absolute Maximum Rating
Power Supply Voltage V Input Voltage V Output Voltage V Power Dissipation P Operating Temperature C-Type
Storage Temperature T
a:Stresses greater than those listed under „Absolute Maximum Ratings“ may cause permanent damage to the device. This is a stress
rating only, and functional operation of the device at condition above those indicated in the operational sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect reliability.
= 0 V and VIH = 3 V. The timing reference level of all input and output signals is 1.5 V,
IL
-times and ten-times, in which cases transition is measured ± 200 mV from steady-state voltage.
dis
a
K-Type
Symbol Min. Max. Unit
CC
I
O
D
T
a
stg
-0.5 7 V
-0.3 VCC+0.5 V
-0.3 VCC+0.5 V
0
-40
-65 150 °C
2
,as well as
I
1W
70 85
°C °C
December 12, 1997
Page 3
U631H64
Recommended Operation Conditions
Power Supply Voltage V
Input Low Voltage V
Input High Voltage V
Symbol Conditions Min. Max. Unit
CC
-2 V at Pulse Width
IL
10 ns permitted
IH
DC Characteristics Symbol Conditions
Operating Supply Current
Average Supply Current during
c
STORE
Standby Supply Current (Cycling TTL Input Levels)
b
d
I
V
CC1
V V
t t t
V
I
CC2
E W V V
I
CC(SB)1VCC
E
= 5.5 V
CC
= 0.8 V
IL
= 2.2 V
IH
= 25 ns
c
= 35 ns
c
= 45 ns
c
= 5.5 V
CC
V
-0.2 V
CC
V
-0.2 V
CC
0.2 V
IL
V
IH
CC
-0.2 V
= 5.5 V V
IH
4.5 5.5 V
-0.3 0.8 V
2.2 VCC+0.3 V
C-Type K-Type
Min. Max. Min. Max.
90 80 75
95 85 80
67mA
Unit
mA mA mA
t
= 25 ns
c
= 35 ns
t
c
= 45 ns
t
c
Average Supply Current at t
= 200 ns
cR
(Cycling CMOS Input Levels)
Standby Supply Current (Stable CMOS Input Levels)
b:I
and I
CC1
The current I
c:I
is the average current requird for the duration of the STORE cycle (STORE Cycle Time).
CC2
d: Bringing E
table. The current I
b
d
are dependent on output loading and cycle rate. The specified values are obtained with outputs unloaded.
CC3
is measured for WRITE/READ - ratio of 1/2.
CC1
VIH will not produce standby current levels until any nonvolatile cycle in progress has timed out. See MODE SELECTION
is measured for WRITE/READ - ratio of 1/2.
CC(SB)1
I
CC(SB)
December 12, 1997
I
CC3
V
= 5.5 V
CC
V
W
0.2 V
V
IL
V
V
IH
V
= 5.5 V
CC
V
E
0.2 V
V
IL
V
V
IH
3
CC
CC
CC
CC
-0.2 V
-0.2 V
-0.2 V
-0.2 V
30 23 20
34 27 23
mA mA mA
15 15 mA
11mA
Page 4
U631H64
DC Characteristics Symbol Conditions
Output High Voltage Output Low Voltage
Output High Current Output Low Current
Input Leakage Current
Output Leakage Current
High at Three-State- Output Low at Three-State- Output
High Low
V V
I I
OH OL
I
OH
I
OL
I
IH
I
IL
OHZ
OLZ
V
CC
I
OH
I
OL
V
CC
V
OH
V
OL
V
CC
V
IH
V
IL
V
CC
V
OH
V
OL
= 4.5 V =-4 mA = 8 mA
= 4.5 V = 2.4 V = 0.4 V 8
= 5.5 V = 5.5 V
= 0 V -1 = 5.5 V
= 5.5 V = 0 V -1
SRAM MEMORY OPERATIONS
Switching Characteristics
No.
Read Cycle
1 Read Cycle Time 2 Address Access Time to Data Valid
f
g
3 Chip Enable Access Time to Data Valid t 4 Output Enable Access Time to Data Valid t 5E
HIGH to Output in High-Z
6G
HIGH to Output in High-Z
h
h
7E LOW to Output in Low-Z t 8G
LOW to Output in Low-Z t
9 Output Hold Time after Addr. Change
g
10Chip Enable to Power Activee t 11Chip Disable to Power Standby
d, e
Symbol 25 35 45
Alt.IECMin.Max.Min.Max.Min.Max.
t
AVAVtcR
t
AVQVta(A)
ELQVta(E)
GLQVta(G)
t
EHQZtdis(E)
t
GHQZtdis(G)
ELQXten(E)
GLQXten(G)
t
AXQXtv(A)
t
ELICCH
t
EHICCL
PU
t
PD
C-Type K-Type
Unit
Min. Max. Min. Max.
2.4
0.4
-4
1
1
2.4
-1
-1
8
0.4VV
-4 mA mA
1 µA
µA
1 µA
µA
Unit
25 35 45 ns
25 35 45 ns 25 35 45 ns 12 20 25 ns 13 17 20 ns
13 17 20 ns 555ns 000ns 333ns 000ns
25 35 45 ns
e: Parameter guaranteed but not tested. f: Device is continuously selected with E g:Address valid prior to or at the same time with E h:Measured ± 200 mV from steady state output voltage.
and G both LOW.
transition LOW.
4
December 12, 1997
Page 5
U631H64
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
Read Cycle 1: Ai-controlled (during Read cycle: E = G = VIL, W = VIH)
1
t
Ai
DQi
Output
Previous Data Valid
9
t
v(A)
Read Cycle 2: G-, E-controlled (during Read cycle: W = VIH)
t
t
en(E)
t
en(G)
10 t
PU
Address Valid
2
a(A)
7
8
Ai
E
G
DQi
Output
I
CC
High Impedance
ACTIVE STANDBY
Address Valid
2
t
a(A)
1
t
cR
3
t
a(E)
4
t
a(G)
cR
g
Output Data Valid
f
Output Data Valid
5
t
dis(E)
6
t
dis(G)
11
t
PD
Switching Characteristics
No.
Write Cycle
12Write Cycle Time t 13Write Pulse Width t 14Write Pulse Width Setup Time t 15Address Setup Time t 16Address Valid to End of Write t 17Chip Enable Setup Time t 18Chip Enable to End of Write t 19Data Setup Time to End of Write t 20Data Hold Time after End of Write t 21Address Hold after End of Write t 22W
LOW to Output in High-Z
23W
HIGH to Output in Low-Z t
h, i
December 12, 1997
Symbol 25 35 45
Alt. #1Alt. #2 IEC Min. Max. Min. Max. Min. Max.
t
AVAVtAVAV
WLWH
WLEHtsu(W)
AVWLtAVELtsu(A)
AVWHtAVEH
ELWH
ELEHtw(E)
DVWHtDVEHtsu(D)
WHDXtEHDXth(D)
WHAXtEHAXth(A)
t
WLQZ
WHQX
t
w(W)
t
su(A-WH)
t
su(E)
t
dis(W)
t
en(W)
25 35 45 ns
cW
20 30 35 ns 20 30 35 ns
000ns 20 30 35 ns 20 30 35 ns 20 30 35 ns 12 18 20 ns
000ns
000ns
10 13 15 ns
555ns
5
Unit
Page 6
U631H64
A
A
A
AAAA
AAAA
A
A
A
AAAA
AAAA
AAAA
A
A
A
A
AAAA
AAAA
A
A
A
A
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAA
AAA
AAA
AAA
AAA
AAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
A
A
A
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAA
AAA
AAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAA
AAA
AAA
Write Cycle #1: W-controlled
Ai
E
W
DQi
Input
DQi
Output
Write Cycle #2: E-controlled
Ai
E
W
DQi
Input
DQi
Output
j
15
t
su(A)
Previous Data
j
15
t
su(A)
12
t
cW
Address Valid
17
t
su(E)
16
t
su(A-WH)
13
t
w(W)
19 20
t
su(D)
Input Data Valid
22
t
dis(W)
High Impedance
12 t
cW
Address Valid
18 21
t
w(E)
14
t
su(W)
19
t
su(D)
Input Data Valid
High Impedance
t
t
h(D)
23
en(W)
t
h(A)
21
t
h(A)
20
t
h(D)
AAA
AAAA
AAA
AAA
AAAA
undefined
i: If W is LOW and when E goes LOW, the outputs remain in the high impedance state. j: E
or W must be
>
during address transitions.
V
IH
AAA
AAAA
AAA
AAA
L- to H-level
AAA
AAA
AAA
AAAA
AAAA
AAAA
6
AAAA
AAAA
AAAA
H- to L-level
AAA
AAA
AAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
December 12, 1997
Page 7
NONVOLATILE MEMORY OPERATIONS
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
A
U631H64
STORE CYCLE INHIBIT and
No.
AUTOMATIC POWER UP RECALL
24Power Up RECALL Duration
k, e
Low Voltage Trigger Level V
k:t
starts from the time VCC rises above V
RESTORE
SWITCH
.
Symbol
Alt. IEC
t
RESTORE
SWITCH
STORE CYCLE INH IBIT and AUTOMATIC POWER UP RECALL
V
CC
5.0 V
V
SWITCH
Power Up RECALL
24
t
RESTORE
Min. Max. Unit
650 µs
4.0 4.5 V
t
STORE inhibit
SOFTWARE MODE SELECTION
E
W
A12 - A0
(hex)
LH0000
1555
0AAA
1FFF 10F0 0F0F
LH0000
1555
0AAA
1FFF 10F0 0F0E
l: The six consecutive addresses must be in order listed (0000, 1555, 0AAA, 1FFF, 10F0, 0F0F) for a Store cycle or (0000, 1555, 0AAA, 1FFF, 10F0, 0F0E) for a RECALL cycle. W
diagrams for further details. The following six-address sequence is used for testing purposes and should not be used: 0000, 1555, 0AAA, 1FFF, 10F0, 139C. m: I/O state assumes that G
VIL. Activation of nonvolatile cycles does not depend on the state of G .
must be high during all six consecutive cycles. See STORE cycle and RECALL cycle tables and
December 12, 1997
Mode I/O Power Notes
Read SRAM Read SRAM Read SRAM Read SRAM Read SRAM
Nonvolatile STORE
Read SRAM Read SRAM Read SRAM Read SRAM Read SRAM
Nonvolatile RECALL
Output Data Output Data Output Data Output Data Output Data
Output High Z
Output Data Output Data Output Data Output Data Output Data
Output High Z
Active
I
CC2
Active l, m
7
l, m l, m l, m l, m l, m
l
l, m l, m l, m l, m
l
Page 8
U631H64
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
A
A
A
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
A
A
A
A
AAAA
AAAA
AAAA
AAA
AAA
AAA
AAAA
AAAA
AAAA
AAAA
A
A
A
A
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
A
A
A
AAAA
AAAA
AAAA
AA
AA
AA
No.Software Controlled STORE/RECALL
25STORE/RECALL Initiation Time t 26Chip Enable to Output Inactive 27STORE Cycle Time 28RECALL Cycle Time 29Address Setup to Chip Enable 30Chip Enable Pulse Width 31Chip Disable to Address Change
n:The software sequence is clocked with E controlled READs. o:Once the software controlled STORE or RECALL cycle is initiated, it completes automatically, ignoring all inputs. p:Note that STORE cycles (but not RECALL) are aborted by V q: An automatic RECALL also takes place at power up, starting when V
V r: Noise on the E s: If the Chip Enable Pulse Width is less than t
the end of the low pulse, however the STORE or RECALL will still be initiated.
SOFTWARE CONTROLLED STORE/RECALL CYCLE
l, n
Cycle
o
p
q
r
r, s
r
once it has been exceeded for the RECALL to function properly.
SWITCH
pin may trigger multiple READ cycles from the same address and abort the address sequence.
(see Read Cycle) but greater than or equal t
a(E)
25
t
cR
Ai
ADDRESS 1
Alt. IEC Min. Max. Min. Max. Min. Max.
< V
t
cR
(STORE inhibit).
SWITCH
exceeds V
CC
r, s, t, u
(E = HIGH after STORE initiation)
AVAV
t
ELQZtdis(E)SR
t
ELQXStd(E)S
t
ELQXRtd(E)R
t
AVELNtsu(A)SR
t
ELEHNtw(E)SR
t
EHAXNth(A)SR
CC
Symbol
25 35 45
25 35 45 ns
600 600 600 ns
10 10 10 ms 20 20 20 µs
000ns
20 25 35 ns
000ns
SWITCH
25
t
cR
ADDRESS 6
and takes t
, than the data may not be valid at
w(E)SR
. VCC must not drop below
RESTORE
31
t
E
High Impedance
DQi
Output
SOFTWARE CONTROLLED STORE/RECALL CYCLE
Ai
t
w(E)SR
29
t
su(A)SR
t
h(A)SR
31
VALID VALID
25
t
cR
ADDRESS 1
29 5
t
su(A)SR
r, s, t, u
(E = LOW after STORE initiation)
30
t
w(E)SR
30
E
29
t
su(A)SR
High Impedance
DQi
Output
t: W must be HIGH when E is LOW during the address sequence in order to initiate a nonvolatile cycle. G may be either HIGH or LOW
throughout. Addresses 1 through 6 are found in the mode selection table. Address 6 determines whether the U631H64 performs a STORE or RECALL.
u:E
must be used to clock in the address sequence for the Software controlled STORE and RECALL cycles.
t
h(A)SR
31
t
su(A)SR
29
VALID VALID
30
t
w(E)SR
ADDRESS 6
h(A)SR
t
dis(E)
26
t
dis(E)SR
t
dis(E)SR
27 28/
t
/ t
d(E)S
d(E)R
31
t
h(A)SR
27 28/
t
/ t
d(E)S
d(E)R
26
Unit
8
December 12, 1997
Page 9
Test Configuration for Functional Check
U631H64
V
CC
A0 A1 A2
A3 A4
V
IH
V
IL
Input level acco rding to the
v:In measurement of t w:Between V
CC
Capacitance
Input Capacitance
Output Capacitance
All pins not under test must be connected with ground by capacitors.
-times and ten-times the capacitance is 5 pF.
dis
and VSS must be connected a high frequency bypass capacitor 0.1 µF to avoid disturbances.
e
V
CC
V
I
f
T
a
A5 A6 A7 A8 A9 A10 A11 A12
relevant test measurement
E W G
V
SS
Conditions Symbol Min. Max. Unit
= 5.0 V = V
SS
= 1MHz = 25 °C
IC Code Numbers
w
DQ0 DQ1 DQ2 DQ3 DQ4 DQ5 DQ6 DQ7
C
I
C
O
5 V
480
V
O
Simultaneous measure-
ment of all 8 output pins
255
30 pF
v
8pF
7pF
Example
DU631H64 25C
B
Type
ESD Class
blank > 2000 V
x
B > 1000 V
Package Access Time
D = PDIP (300 mil) 25 = 25 ns S = SOP (330 mil) 35 = 35 ns (on special request)
45 = 45 ns (on special request)
Operating Temperature Range
C = 0 to 70 °C K = -40 to 85 °C
The date of manufacture is given by the last 4 digits of the mark, the first 2 digits indicating the year, and the last 2 digits the calendar week.
x: ESD protection > 2000 V under development
December 12, 1997
9
Page 10
U631H64
Device Operation
The U631H64 has two separate modes of operation: SRAM mode and nonvolatile mode. In SRAM mode, the memory operates as a standard fast static RAM. In nonvolatile mode, data is transferred from SRAM to EEPROM (the STORE operation) or from EEPROM to SRAM (the RECALL operation). In this mode SRAM functions are disabled.
SRAM READ
The U631H64 performs a READ cycle whenever E G
are LOW while W is HIGH. The address specified on
and
pins A0 - A12 determines which of the 8192 data bytes will be accessed. When the READ is initiated by an address transition, the outputs will be valid after a delay of t
. If the READ is initiated by E or G, the outputs will
cR
be valid at t outputs will repeatedly respond to address changes within the t on any control input pins, and will remain valid until another address change or until E HIGH or W
or at t
a(E)
access time without the need for transition
cR
, whichever is later. The data
a(G)
or G is brought
is brought LOW.
SRAM WRITE
A WRITE cycle is performed whenever E
and W are LOW. The address inputs must be stable prior to entering the WRITE cycle and must remain stable until either E
or W goes HIGH at the end of the cycle. The data on pins DQ0 - 7 will be written into the memory if it is valid t t
su(D)
It is recommended that G
before the end of a W controlled WRITE or
su(D)
before the end of an E controlled WRITE.
is kept HIGH during the en­tire WRITE cycle to avoid data bus contention on the common I/O lines. If G turn off the output buffers t
after W goes LOW.
dis(W)
NOISE CONSIDERATION
The U631H64 is a high speed memory and therefore it must have a high frequency bypass capacitor of appro­ximately 0.1 µF connected between V leads and traces that are as short as possible. As with
and VSS using
CC
all high speed CMOS ICs, normal carefull routing of power, ground and signals will help prevent noise problems.
SOFTWARE NONVOLATILE STORE
The U631H64 software controlled STORE cycle is initiated by executing sequential READ cycles from six specific address locations. By relying on READ cycles only, the U631H64 implements nonvolatile operation while remaining compatible with standard 8K x 8 SRAMs. During the STORE cycle, an erase of the pre-
vious nonvolatile data is first performed, followed by parallel programming of all nonvolatile elements. Once a STORE cycle is initiated, further inputs and outputs are disabled until the cycle is completed. Because a sequence of addresses is used for STORE initiation, it is important that no other READ or WRITE accesses intervene in the sequence or the sequence will be aborted and no STORE or RECALL will take place. To initiate the STORE cycle the following READ sequence must be performed:
1. Read address 0000 (hex)Valid READ
2. Read address 1555 (hex)Valid READ
3. Read address 0AAA(hex)Valid READ
4. Read address 1FFF(hex)Valid READ
5. Read address 10F0 (hex)Valid READ
6. Read address 0F0F(hex)Initiate STORE Once the sixth address in the sequence has been
entered, the STORE cycle will commence and the chip will be disabled. It is important that REA D cycles and not WRITE cycles are used in the sequence. It is not necessary that G After the t will again be activated for READ and WRITE opera-
is LOW for the sequence to be valid.
cycle time has been fulfilled, the SRAM
STORE
tion.
SOFTWARE NONVOLATILE RECALL
A RECALL cycle of the EEPROM data into the SRAM is initiated with a sequence of READ operations in a manner similar to the STORE initiation. To initiate the RECALL cycle the following sequence of READ opera­tions must be performed:
1. Read address 0000 (hex)Valid READ
2. Read address 1555 (hex)Valid READ
3. Read address 0AAA(hex)Valid READ
4. Read address 1FFF(hex)Valid READ
5. Read address 10F0 (hex)Valid READ
6. Read address 0F0E(hex)Initiate RECALL Internally, RECALL is a two step procedure. First, the
SRAM data is cleared and second, the nonvolatile information is transferred into the SRAM cells. The RECALL operation in no way alters the data in the EEPROM cells. The nonvolatile data can be recalled an unlimited number of times.
AUTOMATIC POWER UP RECALL
On power up, once V V
, a RECALL cycle is automatically initiated. The
SWITCH
voltage on the V once it has risen above it in order for the RECALL to
exceeds the sense voltage of
CC
pin must not drop below V
CC
SWITCH
operate properly.
10
December 12, 1997
Page 11
U631H64
Due to this automatic RECALL, SRAM operation cannot commence until t V
.
SWITCH
If the U631H64 is in a WRITE state at the end of power
after VCC exceeds
RESTORE
up RECALL, the SRAM data will be corrupted. To help avoid this situation, a 10 K resistor should be connected between W
and V
CC
.
HARDWARE PROTECTION
The U631H64 offers hardware protection against inad­vertent STORE operation through V For V
< V
CC
tion will be inhibited.
the software initiated STORE opera-
SWITCH
sense.
CC
LOW AVERAGE ACTIVE POWER
The U631H64 has been designed to draw significantly less power when E
is LOW (chip enabled) but the access cycle time is longer than 55 ns. When E
is HIGH the chip consumes only standby cur­rent. The overall average current drawn by the part depends on the following items:
1. CMOS or TTL input levels
2. the time during which the chip is disabled (E
3. the cycle time for accesses (E
LOW)
HIGH)
4. the ratio of READs to WRITEs
5. the operating temperature
6. the V
CC
level
December 12, 1997
11
Page 12
Memory Products 1998
SoftStore 8K x 8 nvSRAM U631H64
LIFE SUPPORT POLICY
ZMD products are not designed, intended, or authorized for use as components in systems intend for surgical implant into the body, or other applications intended to support or sustain life, or for any other application in which the failure of the ZMD product could create a situation where personal injury or death may occur. Components used in life-support devices or systems must be expressly authorized by ZMD for such purpose.
The information describes the type of component and shall not be considered as assured characteristics.
Terms of delivery and rights to change design reserved.
Zentrum Mikroelektronik Dresden GmbH
Grenzstraße 28
Phone: +49 351 88 22-3 06 • Fax: +49 351 88 22-3 37 • Email: sales@zmd.de
• D-01109 Dresden P. O. B. 80 01 34 D-01101 Dresden Germany
Internet Web Site: http://www.zmd.de
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