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Электронный компонент: BQ4011YMA-70

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Features
Data retention in the absence of
power
Automatic write-protection
during power-up/power-down
cycles
Industry-standard 28-pin 32K x
8 pinout
Conventional SRAM operation;
unlimited write cycles
10-year minimum data retention
in absence of power
Battery internally isolated until
power is applied
General Description
The CMOS bq4011 is a nonvolatile
262,144-bit static RAM organized as
32,768 words by 8 bits. The integral
control circuitry and lithium energy
source provide reliable nonvolatility
coupled with the unlimited write
cycles of standard SRAM.
The control circuitry constantly
monitors the single 5V supply for an
out-of-tolerance condition. When
V
CC
falls out of tolerance, the SRAM
is unconditionally write-protected to
prevent inadvertent write operation.
At this time the integral energy
source is switched on to sustain the
memory until after V
CC
returns valid.
The bq4011 uses an extremely low
standby current CMOS SRAM,
coupled with a small lithium coin cell
to provide nonvolatility without long
write-cycle times and the write-cycle
limitations associated with EEPROM.
The bq4011 requires no external cir-
cuitry and is socket-compatible with
industry-standard SRAMs and most
EPROMs and EEPROMs.
Selection Guide
Part
Number
Maximum
Access
Time (ns)
Negative
Supply
Tolerance
Part
Number
Maximum
Access
Time (ns)
Negative
Supply
Tolerance
bq4011Y-70
70
-10%
bq4011 -100
100
-5%
bq4011Y -100
100
-10%
bq4011 -150
150
-5%
bq4011Y -150
150
-10%
bq4011 -200
200
-5%
bq4011Y -200
200
-10%
Pin Names
A
0
A
14
Address inputs
DQ
0
DQ
7
Data input/output
CE
Chip enable input
OE
Output enable input
WE
Write enable input
V
CC
+5 volt supply input
V
SS
Ground
Aug. 1993 C
32Kx8 Nonvolatile SRAM
bq4011/bq4011Y
Block Diagram
Pin Connections
1
Functional Description
When power is valid, the bq4011 operates as a standard
CMOS SRAM. During power-down and power-up cycles,
the bq4011 acts as a nonvolatile memory, automatically
protecting and preserving the memory contents.
Power-down/power-up control circuitry constantly
monitors the V
CC
supply for a power-fail-detect threshold
V
PFD
. The bq4011 monitors for V
PFD
= 4.62V typical for
use in systems with 5% supply tolerance. The bq4011Y
monitors for V
PFD
= 4.37V typical for use in systems with
10% supply tolerance.
When V
CC
falls below the V
PFD
threshold, the SRAM
automatically write-protects the data. All outputs
become high impedance, and all inputs are treated as
"don't care." If a valid access is in process at the time of
power-fail detection, the memory cycle continues to com-
pletion. If the memory cycle fails to terminate within
time t
WPT
, write-protection takes place.
As V
CC
falls past V
PFD
and approaches 3V, the control
circuitry switches to the internal lithium backup supply,
which provides data retention until valid V
CC
is applied.
When V
CC
returns to a level above the internal backup
cell voltage, the supply is switched back to V
CC.
After
V
CC
ramps above the V
PFD
threshold, write-protection
continues for a time t
CER
(120ms maximum) to allow for
processor stabilization. Normal memory operation may
resume after this time.
The internal coin cell used by the bq4011 has an
extremely long shelf life and provides data retention for
more than 10 years in the absence of system power.
As shipped from Benchmarq, the integral lithium cell is
electrically isolated from the memory. (Self-discharge in
this condition is approximately 0.5% per year.) Following
the first application of V
CC
, this isolation is broken, and
the lithium backup cell provides data retention on sub-
sequent power-downs.
bq4011/bq4011Y
Truth Table
Mode
CE
WE
OE
I/O Operation
Power
Not selected
H
X
X
High Z
Standby
Output disable
L
H
H
High Z
Active
Read
L
H
L
D
OUT
Active
Write
L
L
X
D
IN
Active
Absolute Maximum Ratings
Symbol
Parameter
Value
Unit
Conditions
V
CC
DC voltage applied on V
CC
relative to V
SS
-0.3 to 7.0
V
V
T
DC voltage applied on any pin excluding V
CC
relative to V
SS
-0.3 to 7.0
V
V
T
V
CC
+ 0.3
T
OPR
Operating temperature
0 to +70
C
Commercial
-40 to +85
C
Industrial "N"
T
STG
Storage temperature
-40 to +70
C
Commercial
-40 to +85
C
Industrial "N"
T
BIAS
Temperature under bias
-10 to +70
C
Commercial
-40 to +85
C
Industrial "N"
T
SOLDER
Soldering temperature
+260
C
For 10 seconds
Note:
Permanent device damage may occur if Absolute Maximum Ratings are exceeded. Functional operation
should be limited to the Recommended DC Operating Conditions detailed in this data sheet. Exposure to
conditions beyond the operational limits for extended periods of time may affect device reliability.
Aug. 1993 C
2
bq4011/bq4011Y
Recommended DC Operating Conditions
(TA = TOPR)
Symbol
Parameter
Minimum
Typical
Maximum
Unit
Notes
V
CC
Supply voltage
4.5
5.0
5.5
V
bq4011Y/bq4011Y-xxxN
4.75
5.0
5.5
V
bq4011
V
SS
Supply voltage
0
0
0
V
V
IL
Input low voltage
-0.3
-
0.8
V
V
IH
Input high voltage
2.2
-
V
CC
+ 0.3
V
Note:
Typical values indicate operation at T
A
= 25C.
DC Electrical Characteristics
(TA = TOPR, VCCmin
VCC
VCCmax)
Symbol
Parameter
Minimum
Typical
Maximum
Unit
Conditions/Notes
I
LI
Input leakage current
-
-
1
A
V
IN
= V
SS
to V
CC
I
LO
Output leakage current
-
-
1
A
CE = V
IH
or OE = V
IH
or
WE = V
IL
V
OH
Output high voltage
2.4
-
-
V
I
OH
= -1.0 mA
V
OL
Output low voltage
-
-
0.4
V
I
OL
= 2.1 mA
I
SB1
Standby supply current
-
4
7
mA
CE = V
IH
I
SB2
Standby supply current
-
2.5
4
mA
CE
V
CC
- 0.2V,
0V
V
IN
0.2V,
or V
IN
V
CC
- 0.2V
I
CC
Operating supply current
-
55
75
mA
Min. cycle, duty = 100%,
CE = V
IL
, I
I/O
= 0mA
V
PFD
Power-fail-detect voltage
4.55
4.62
4.75
V
bq4011
4.30
4.37
4.50
V
bq4011Y
V
SO
Supply switch-over voltage
-
3
-
V
Note:
Typical values indicate operation at T
A
= 25C, V
CC
= 5V.
Capacitance
(TA = 25C, F = 1MHz, VCC = 5.0V)
Symbol
Parameter
Minimum
Typical
Maximum
Unit
Conditions
C
I/O
Input/output capacitance
-
-
10
pF
Output voltage = 0V
C
IN
Input capacitance
-
-
10
pF
Input voltage = 0V
Note:
These parameters are sampled and not 100% tested.
Aug. 1993 C
3
bq4011/bq4011Y
AC Test Conditions
Parameter
Test Conditions
Input pulse levels
0V to 3.0V
Input rise and fall times
5 ns
Input and output timing reference levels
1.5 V (unless otherwise specified)
Output load (including scope and jig)
See Figures 1 and 2
Figure 1. Output Load A
Figure 2. Output Load B
Read Cycle
(TA = TOPR, VCCmin
VCC
VCCmax)
Symbol
Parameter
-70/-70N
-100
-150/-150N
-200
Unit
Conditions
Min.
Max.
Min.
Max.
Min.
Max. Min.
Max.
t
RC
Read cycle time
70
-
100
-
150
-
200
-
ns
t
AA
Address access time
-
70
-
100
-
150
-
200
ns
Output load A
t
ACE
Chip enable access time
-
70
-
100
-
150
-
200
ns
Output load A
t
OE
Output enable to
output valid
-
35
-
50
-
70
-
90
ns
Output load A
t
CLZ
Chip enable to output
in low Z
5
-
5
-
10
-
10
-
ns
Output load B
t
OLZ
Output enable to
output in low Z
5
-
5
-
5
-
5
-
ns
Output load B
t
CHZ
Chip disable to output
in high Z
0
25
0
40
0
60
0
70
ns
Output load B
t
OHZ
Output disable to
output in high Z
0
25
0
35
0
50
0
70
ns
Output load B
t
OH
Output hold from
address change
10
-
10
-
10
-
10
-
ns
Output load A
Aug. 1993 C
4
bq4011/bq4011Y
Aug. 1993 C
Read Cycle No. 2 (CE Access)
1,3,4
Read Cycle No. 1 (Address Access)
1,2
Notes:
1.
WE is held high for a read cycle.
2.
Device is continuously selected: CE = OE = V
IL
.
3. Address is valid prior to or coincident with CE transition low.
4. OE = V
IL
.
5.
Device is continuously selected: CE = V
IL
.
Read Cycle No. 3 (OE Access)
1,5
5