SIMTEK U635H64SK35

Obsolete - Not Recommended for New Designs
U635H64
PowerStore 8K x 8 nvSRAM
Features
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High-performance CMOS nonvolatile static RAM 8192 x 8 bits
25, 35 and 45 ns Access Times
12, 20 and 25 ns Output Enable
Access Times
ICC = 15 mA at 200 ns Cycle
Time
Automatic STORE to EEPROM
on Power Down using system
capacitance
Software initiated STORE
(STORE Cycle Time < 10 ms)
Automatic STORE Timing
105 STORE cycles to EEPROM
10 years data retention in
EEPROM
Automatic RECALL on Power Up
Software RECALL Initiation
(RECALL Cycle Time < 20 μs)
Unlimited RECALL cycles from
EEPROM
Single 5 V ± 10 % Operation
Operating temperature ranges:
0 to 70 °C
-40 to 85 °C
QS 9000 Quality Standard
ESD characterization accordingMIL STD 883C M3015.7-HBM
(classification see IC Code
Numbers)
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RoHS compliance and Pb- free
Packages: PDIP28 (600 mil)
SOP28 (330 mil)
Description
The U635H64 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 U635H64 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) take place
automatically upon power down
using charge stored in system
capacitance.
Transfers from the EEPROM to the
SRAM (the RECALL operation)
take place automatically on power
up. The U635H64 combines the
high performance and ease of use
of a fast SRAM with nonvolatile
data integrity.
STORE cycles also may be initiated
under user control via a software
sequence.
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.
RECALL cycles may also be initiated by a software sequence.
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.
Pin Description
Pin Configuration
n.c.
1
28
VCC
A12
2
27
W
A7
3
26
n.c.
Signal Name
Signal Description
A6
4
25
A8
A0 - A12
Address Inputs
A5
5
24
A9
DQ0 - DQ7
Data In/Out
A4
6
23
A11
A3
7
G
E
Chip Enable
A2
8
PDIP 22
SOP 21
G
Output Enable
A1
9
20
E
Write Enable
A0
10
19
DQ7
W
VCC
Power Supply Voltage
DQ0
11
18
DQ6
VSS
Ground
DQ1
12
17
DQ5
DQ2
13
16
DQ4
VSS
14
15
DQ3
A10
Top View
March 31, 2006
STK Control #ML0052
1
Rev 1.0
U635H64
Block Diagram
EEPROM Array
128 x (64 x 8)
VCC
VSS
STORE
A5
Row Decoder
A6
A7
A8
A9
A11
SRAM
Array
RECALL
Power
Control
VCC
128 Rows x
64 x 8 Columns
Store/
Recall
Control
A12
DQ0
DQ1
Input Buffers
Column I/O
DQ2
DQ3
DQ4
DQ5
DQ6
Software
Detect
Column Decoder
A0 - A12
G
A0 A1 A2 A3 A4 A10
DQ7
E
W
Truth Table for SRAM Operations
Operating Mode
E
W
G
DQ0 - DQ7
Standby/not selected
H
*
*
High-Z
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
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 VI, as well as
input levels of VIL = 0 V and VIH = 3 V. The timing reference level of all input and output signals is 1.5 V,
with the exception of the tdis-times and ten-times, in which cases transition is measured ± 200 mV from steady-state voltage.
Absolute Maximum Ratingsa
Symbol
Min.
Max.
Unit
VCC
-0.5
7
V
Input Voltage
VI
-0.3
VCC+0.5
V
Output Voltage
VO
-0.3
VCC+0.5
V
Power Dissipation
PD
1
W
Power Supply Voltage
Operating Temperature
Storage Temperature
a:
C-Type
K-Type
Ta
0
-40
70
85
°C
°C
Tstg
-65
150
°C
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.
STK Control #ML0052
2
Rev 1.0
March 31, 2006
U635H64
Recommended
Operating Conditions
Symbol
Power Supply Voltage
VCC
Input Low Voltage
VIL
Input High Voltage
VIH
DC Characteristics
Symbol
Conditions
-2 V at Pulse Width
10 ns permitted
Min.
Max.
Unit
4.5
5.5
V
-0.3
0.8
V
2.2
VCC+0.3
V
C-Type
K-Type
Conditions
Unit
Min.
Operating Supply Currentb
ICC1
Max.
Min.
Max.
VCC
VIL
VIH
= 5.5 V
= 0.8 V
= 2.2 V
tc
tc
tc
= 25 ns
= 35 ns
= 45 ns
90
80
75
95
85
80
mA
mA
mA
Average Supply Current during
STOREc
ICC2
VCC
E
W
VIL
VIH
= 5.5 V
≤ 0.2 V
≥ VCC-0.2 V
≤ 0.2 V
≥VCC-0.2 V
6
7
mA
Average Supply Current during
PowerStore Cyclec
ICC4
VCC
VIL
VIH
= 4.5 V
= 0.2 V
≥ VCC-0.2 V
4
4
mA
ICC(SB)1
VCC
E
tc
tc
tc
= 5.5 V
= VIH
= 25 ns
= 35 ns
= 45 ns
30
23
20
34
27
23
mA
mA
mA
Standby Supply Currentd
(Cycling TTL Input Levels)
Operating Supply Current
at tcR = 200 nsb
(Cycling CMOS Input Levels)
ICC3
VCC
W
VIL
VIH
= 5.5 V
≥ VCC-0.2 V
≤ 0.2 V
≥ VCC-0.2 V
15
15
mA
Standby Supply Curentd
(Stable CMOS Input Levels)
ICC(SB)
VCC
E
VIL
VIH
= 5.5 V
≥ VCC-0.2 V
≤ 0.2 V
≥ VCC-0.2 V
3
3
mA
b: ICC1 and ICC3 are depedent on output loading and cycle rate. The specified values are obtained with outputs unloaded.
The current ICC1 is measured for WRITE/READ - ratio of 1/2.
c: ICC2 and ICC4 are the average currents required for the duration of the respective STORE cycles (STORE Cycle Time).
d: Bringing E ≥ VIH will not produce standby current levels until any nonvolatile cycle in progress has timed out. See MODE SELECTION
table. The current ICC(SB)1 is measured for WRITE/READ - ratio of 1/2.
March 31, 2006
STK Control #ML0052
3
Rev 1.0
U635H64
C-Type
DC Characteristics
Symbol
Unit
Min.
Output High Voltage
Output Low Voltage
VOH
VOL
VCC
IOH
IOL
= 4.5 V
=-4 mA
= 8 mA
Output High Current
Output Low Current
IOH
IOL
VCC
VOH
VOL
= 4.5 V
= 2.4 V
= 0.4 V
VCC
= 5.5 V
VIH
VIL
= 5.5 V
= 0V
VCC
= 5.5 V
VOH
VOL
= 5.5 V
= 0V
Input Leakage Current
High
Low
IIH
IIL
Output Leakage Current
High at Three-State- Output
Low at Three-State- Output
IOHZ
IOLZ
K-Type
Conditions
Max.
2.4
Min.
Max.
2.4
0.4
0.4
-4
8
-4
mA
mA
1
μA
μA
8
1
-1
-1
1
1
-1
V
V
-1
μA
μA
SRAM Memory Operations
No.
e:
f:
g:
h:
Switching Characteristics
Read Cycle
Symbol
25
35
45
Unit
Alt.
IEC
Min. Max. Min. Max. Min. Max.
1
Read Cycle Timef
tAVAV
tcR
2
Address Access Time to Data Validg
tAVQV
ta(A)
25
35
45
ns
3
Chip Enable Access Time to Data Valid
tELQV
ta(E)
25
35
45
ns
4
Output Enable Access Time to Data Valid
tGLQV
ta(G)
12
20
25
ns
5
E HIGH to Output in High-Zh
tEHQZ
tdis(E)
13
17
20
ns
6
G HIGH to Output in High-Zh
tGHQZ
tdis(G)
13
17
20
ns
7
E LOW to Output in Low-Z
tELQX
ten(E)
5
5
5
ns
8
G LOW to Output in Low-Z
tGLQX
ten(G)
0
0
0
ns
9
Output Hold Time after Address Change
tAXQX
tv(A)
3
3
3
ns
10 Chip Enable to Power Activee
tELICCH
tPU
0
0
0
ns
11 Chip Disable to Power Standbyd, e
tEHICCL
tPD
25
35
25
45
35
ns
45
ns
Parameter guaranteed but not tested.
Device is continuously selected with E and G both LOW.
Address valid prior to or coincident with E transition LOW.
Measured ± 200 mV from steady state output voltage.
STK Control #ML0052
4
Rev 1.0
March 31, 2006
U635H64
Read Cycle 1: Ai-controlled (during Read cycle: E = G = VIL, W = VIH)f
tcR (1)
Ai
Address Valid
ta(A) (2)
DQi
Previous Data Valid
Output
Output Data Valid
tv(A) (9)
Read Cycle 2: G-, E-controlled (during Read cycle: W = VIH)g
tcR (1)
Ai
Address Valid
ta(A) (2)
ta(E) (3)
E
tdis(E) (5)
ten(E) (7)
G
ta(G) (4)
tdis(G) (6)
ten(G) (8)
DQi
High Impedance
Output
Output Data Valid
tPU (10)
ACTIVE
ICC
No.
tPD (11)
STANDBY
Switching Characteristics
Write Cycle
Symbol
25
35
45
Unit
Alt. #1 Alt. #2
12 Write Cycle Time
tAVAV
13 Write Pulse Width
tWLWH
14 Write Pulse Width Setup Time
tAVAV
IEC
Min. Max. Min. Max. Min. Max.
tcW
25
35
45
ns
tw(W)
20
30
35
ns
tWLEH
tsu(W)
20
30
35
ns
15 Address Setup Time
tAVWL
tAVEL
tsu(A)
0
0
0
ns
16 Address Valid to End of Write
tAVWH
tAVEH
tsu(A-WH)
20
30
35
ns
17 Chip Enable Setup Time
tELWH
tsu(E)
20
30
35
ns
tELEH
tw(E)
20
30
35
ns
18 Chip Enable to End of Write
19 Data Setup Time to End of Write
tDVWH
tDVEH
tsu(D)
12
18
20
ns
20 Data Hold Time after End of Write
tWHDX
tEHDX
th(D)
0
0
0
ns
21 Address Hold after End of Write
tWHAX
tEHAX
th(A)
0
0
0
ns
22 W LOW to Output in High-Zh, i
tWLQZ
tdis(W)
23 W HIGH to Output in Low-Z
tWHQX
ten(W)
March 31, 2006
STK Control #ML0052
5
10
5
13
5
Rev 1.0
15
5
ns
ns
U635H64
Write Cycle #1: W-controlledj
tcW (12)
Ai
Address Valid
tsu(E) (17)
th(A) (21)
E
tsu(A-WH)
W
DQi
(16)
tw(W)
tsu(A) (15)
(13)
tsu(D) (19)
th(D) (20)
Input
Input Data Valid
DQi
tdis(W) (22)
ten(W) (23)
High Impedance
Output
Previous Data
Write Cycle #2: E-controlledj
tcW (12)
Ai
tsu(A) (15)
E
Address Valid
tw(E) (18)
th(A) (21)
tsu(W) (14)
W
th(D) (20)
tsu(D) (19)
DQi
Input
Input Data Valid
DQi
High Impedance
Output
undefined
i:
j:
L- to H-level
H- to L-level
If W is LOW and when E goes LOW, the outputs remain in the high impedance state.
E or W must be VIH during address transition.
STK Control #ML0052
6
Rev 1.0
March 31, 2006
U635H64
Nonvolatile Memory Operations
Mode Selection
E
W
A12 - A0
(hex)
Mode
I/O
Power
H
X
X
Not Selected
Output High Z
Standby
L
H
X
Read SRAM
Output Data
Active
L
L
X
Write SRAM
Input Data
Active
L
H
0000
1555
0AAA
1FFF
10F0
0F0F
Read SRAM
Read SRAM
Read SRAM
Read SRAM
Read SRAM
Nonvolatile STORE
Output Data
Output Data
Output Data
Output Data
Output Data
Output High Z
Active
k, l
k, l
k, l
k, l
k, l
k
L
H
0000
1555
0AAA
1FFF
10F0
0F0E
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
Active
k, l
k, l
k, l
k, l
k, l
k
Notes
m
k:
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 must be high during all six consecutive cycles.
See STORE cycle and RECALL cycle tables and 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.
l: Activation of nonvolatile cycles does not depend on the state of G.
m: I/O state assumes that G ≤ VIL.
No.
PowerStore
Power Up RECALL
24 Power Up RECALL Durationn, e
25 STORE Cycle Durationf
26
Time allowed to Complete SRAM Cyclef,
e
Low Voltage Trigger Level
n:
Symbol
Conditions
Alt.
tRESTORE
tPDSTORE
the power supply voltage must stay above
3.6 V for at least
10 ms after the start
of the STORE
operation
tDELAY
4.0
VSWITCH
tRESTORE starts from the time VCC rises above VSWITCH.
March 31, 2006
STK Control #ML0052
Min.
Max.
Unit
650
μs
10
ms
1
μs
4.5
V
IEC
7
Rev 1.0
U635H64
PowerStore and automatic Power Up RECALL
VCC
5.0 V
VSWITCH
t
PowerStore
(25)
tPDSTOREp
Power Up
RECALL
(24)
(24)
tRESTORE
tRESTORE
W
(26)
tDELAY
DQi
POWER UP
RECALL
No.
o:
p:
q:
r:
s:
t:
Software Controlled STORE/
RECALL Cyclek, o
BROWN OUT
NO STORE
(NO SRAM WRITES)
BROWN OUT
PowerStore
Symbol
25
35
45
Unit
Alt.
IEC
Min. Max. Min. Max. Min. Max.
27 STORE/RECALL Initiation Time
tAVAV
tcR
28 Chip Enable to Output Inactivep
tELQZ
tdis(E)SR
600
600
600
ns
29 STORE Cycle Timeq
tELQXS
td(E)S
10
10
10
ms
30 RECALL Cycle Timer
tELQXR
td(E)R
20
20
20
μs
31 Address Setup to Chip Enables
tAVELN
tsu(A)SR
0
0
0
ns
32 Chip Enable Pulse Widths, t
tELEHN
tw(E)SR
20
25
35
ns
33 Chip Disable to Address Changes
tEHAXN
th(A)SR
0
0
0
ns
25
35
45
ns
The software sequence is clocked with E controlled READs.
Once the software controlled STORE or RECALL cycle is initiated, it completes automatically, ignoring all inputs.
Note that STORE cycles (but not RECALL) are aborted by VCC < VSWITCH (STORE inhibit).
An automatic RECALL also takes place at power up, starting when VCC exceeds VSWITCH and takes tRESTORE. VCC must not drop below
VSWITCH once it has been exceeded for the RECALL to function properly.
Noise on the E pin may trigger multiple READ cycles from the same address and abort the address sequence.
If the Chip Enable Pulse Width is less than ta(E) (see Read Cycle) but greater than or equal tw(E)SR, than the data may not be valid at
the end of the low pulse, however the STORE or RECALL will still be initiated.
STK Control #ML0052
8
Rev 1.0
March 31, 2006
U635H64
Software Controlled STORE/RECALL Cycles, t, u, v (E = HIGH after STORE initiation)
tcR (27)
Ai
tcR (27)
ADDRESS 1
tw(E)SR
E
DQi
(32)
tsu(A)SR (31)
(33) th(A)SR
High Impedance
ADDRESS 6
th(A)SR (33)
tw(E)SR
tdis(E)(5)
(32)
(31)
tsu(A)SR
VALID
Output
td(E)S (29)
td(E)R (30)
VALID
tdis(E)SR (28)
Software Controlled STORE/RECALL Cycles, t, u, v (E = LOW after STORE initiation)
tcR (27)
Ai
E
DQi
Output
ADDRESS 1
ADDRESS 6
th(A)SR (33)
tw(E)SR
tsu(A)SR (31)
High Impedance
(32)
(31)
(33) th(A)SR
tsu(A)SR
VALID
td(E)S (29)
td(E)R (30)
VALID
tdis(E)SR (28)
u: 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 U635H64 performs a STORE
or RECALL.
v: E must be used to clock in the address sequence for the software controlled STORE and RECALL cycles.
March 31, 2006
STK Control #ML0052
9
Rev 1.0
U635H64
Test Configuration for Functional Check
5V
DQ1
DQ2
DQ3
DQ4
DQ5
DQ6
DQ7
E
W
G
ment of all 8 output pins
VIL
DQ0
Simultaneous measure-
VIH
A0
A1
A2
A3
A4
A5
A6
A7
A8
A9
A10
A11
A12
relevant test measurement
Input level according to the
VCCx
480
VO
30 pF w
255
VSS
w: In measurement of tdis-times and ten-times the capacitance is 5 pF.
x: Between VCC and VSS must be connected a high frequency bypass capacitor 0.1 μF to avoid disturbances.
Capacitancee
Conditions
VCC
VI
f
Ta
Input Capacitance
Output Capacitance
Symbol
= 5.0 V
= VSS
= 1 MHz
= 25 °C
Min.
Max.
Unit
CI
8
pF
CO
7
pF
All pins not under test must be connected with ground by capacitors.
Ordering Code
Example
U635H64
S
C
25 G1
Type
Leadfree Option
blank = Standard Package
G1 = Leadfree Green Package y
ESD Class
blank > 2000 V
B
> 1000 V
Package
D1 = PDIP28 (600 mil)
S = SOP28 (330 mil) Type 1
S2 = SOP28 (330 mil) Type 2
Access Time
25 = 25 ns
35 = 35 ns y
45 = 45 ns y
Operating Temperature Range
C = 0 to 70 °C
K = -40 to 85 °C
y: on special request
Device Marking (example)
Product specification
ZMD
U635H64S2C
25 Z 0425
G1
Date of manufacture
(The first 2 digits indicating
the year, and the last 2
digits the calendar week.)
Leadfree Green Package
Internal Code
STK Control #ML0052
10
Rev 1.0
March 31, 2006
U635H64
Device Operation
The U635H64 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.
STORE cycles may be initiated under user control via a
software sequence and are also automatically initiated
when the power supply voltage level of the chip falls
below VSWITCH. RECALL operations are automatically
initiated upon power up and may occur also when VCC
rises above VSWITCH after a low power condition.
RECALL cycles may also be initiated by a software
sequence.
matic STORE will be ignored unless at least one
WRITE operation has taken place since the most
recent STORE or RECALL cycle. Software initiated
STORE cycles are performed regardless of whether or
not a WRITE operation has taken place.
Automatic RECALL
During power up an automatic RECALL takes place.
After any low power condition (VCC < VSWITCH) an internal RECALL request may be latched. When VCC once
again exceeds the sense voltage of VSWITCH, a requested RECALL cycle will automatically be initiated and
will take tRESTORE to complete.
If the U635H64 is in a WRITE state at the end of a
power up RECALL, the SRAM data will be corrupted.
To help avoid this situation, a 10 KΩ resistor should be
connected between W and system VCC.
SRAM READ
Software Nonvolatile STORE
The U635H64 performs a READ cycle whenever E and
G are LOW and W are HIGH. The address specified on
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 tcR. If the READ is initiated by E or G, the outputs will
be valid at ta(E) or at ta(G), whichever is later. The data
outputs will repeatedly respond to address changes
within the tcR access time without the need for transition
on any control input pins, and will remain valid until
another address change or until E or G is brought
HIGH or W 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 tsu(D) before the end of a W controlled WRITE or
tsu(D) before the end of an E controlled WRITE.
It is recommended that G is kept HIGH during the entire WRITE cycle to avoid data bus contention on the
common I/O lines. If G is left LOW, internal circuitry will
turn off the output buffers tdis(W) after W goes LOW.
Automatic STORE
The U635H64 uses the intrinsic system capacitance to
perform an automatic STORE on power down. As long
as the system power supply take at least tPDSTORE to
decay from VSWITCH down to 3.6 V the U635H64 will
safely and automatically STORE the SRAM data in
EEPROM on power down.
In order to prevent unneeded STORE operations, auto-
March 31, 2006
STK Control #ML0052
11
The U635H64 software controlled STORE cycle is
initiated by executing sequential READ cycles from six
specific address locations. By relying on READ cycles
only, the U635H64 implements nonvolatile operation
while remaining compatible with standard 8K x 8
SRAMs. During the STORE cycle, an erase of the previous nonvolatile data is performed first, followed by a
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.
To initiate the STORE cycle the following READ
sequence must be performed:
1.
2.
3.
4.
5.
6.
Read address
Read address
Read address
Read address
Read address
Read address
0000
1555
0AAA
1FFF
10F0
0F0F
(hex)
(hex)
(hex)
(hex)
(hex)
(hex)
Valid READ
Valid READ
Valid READ
Valid READ
Valid READ
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 READ cycles and
not WRITE cycles are used in the sequence, although it
is not necessary that G is LOW for the sequence to be
valid. After the tSTORE cycle time has been fulfilled, the
SRAM will again be activated for READ and WRITE
operation.
Rev 1.0
U635H64
Software Nonvolatile RECALL
Hardware Protection
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:
The U635H64 offers hardware protection against inadvertent STORE operation through VCC Sense. When
VCC < VSWITCH all software controlled STORE operations will be inhibited.
Low Average Active Power
1.
2.
3.
4.
5.
6.
Read address
Read address
Read address
Read address
Read address
Read address
0000
1555
0AAA
1FFF
10F0
0F0E
(hex)
(hex)
(hex)
(hex)
(hex)
(hex)
Valid READ
Valid READ
Valid READ
Valid READ
Valid READ
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.
The U635H64 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 HIGH)
3. the cycle time for accesses (E LOW)
4. the ratio of READs to WRITEs
5. the operating temperature
6. the VCC level
The information describes the type of component and shall not be considered as assured characteristics. Terms of
delivery and rights to change design reserved.
STK Control #ML0052
12
Rev 1.0
March 31, 2006
U635H64
LIFE SUPPORT POLICY
Simtek products are not designed, intended, or authorized for use as components in systems intended 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 Simtek 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 Simtek for such purpose.
LIMITED WARRANTY
The information in this document has been carefully checked and is believed to be reliable. However, Simtek makes
no guarantee or warranty concerning the accuracy of said information and shall not be responsible for any loss or
damage of whatever nature resulting from the use of, or reliance upon it. The information in this document describes the type of component and shall not be considered as assured characteristics.
Simtek does not guarantee that the use of any information contained herein will not infringe upon the patent, trademark, copyright, mask work right or other rights of third parties, and no patent or licence is implied hereby. This
document does not in any way extent Simtek’s warranty on any product beyond that set forth in its standard terms
and conditions of sale.
Simtek reserves terms of delivery and reserves the right to make changes in the products or specifications, or both,
presented in this publication at any time and without notice.
March 31, 2006
Change record
Date/Rev
Name
Change
01.11.2001
Ivonne Steffens
format revision and release for „Memory CD 2002“
25.09.2002
Matthias Schniebel
Adding „Type 1“ to SOP28 (330mil)
20.04.2004
Matthias Schniebel
adding „Leadfree Green Package“ to ordering information
adding „Device Marking“
7.4.2005
Stefan Günther
adding RoHS compliance and Pb- free, S2 for chippack and delete
PDIP28 (300mil)
31.3.2006
Troy Meester
changed to obsolete status
Simtek
Assigned Simtek Document Control Number
1.0