Features
•
Fast Read Access Time - 45 ns
•
Low-Power CMOS Operation
•
– 100 µA max. Standby
– 20 mA max. Active at 5 MHz
JEDEC Standard Packages
– 28-Lead 600-mil PDIP
– 32-Lead PLCC
– 28-Lead TSOP and SOIC
5V
±
10% Supply
High Reliability CMOS Technology
– 2,000V ESD Protection
– 200 mA Latchup Immunity
Rapid™ Programming Algorithm - 100 µs/byte (typical)
CMOS and TTL Compatible Inputs and Outputs
Integrated Product Identification Code
Commercial, Industrial and Automotive Temperature Ranges
•
•
•
•
•
•
256K (32K x 8)
OTP EPROM
AT27C256R
Description
The AT27C256R is a low-power, high-performance 262,144-bit one-time programma-
ble read only memory (OTP EPROM) organized 32K by 8 bits. It requires only one 5V
power supply in normal read mode operation. Any byte can be accessed in less than
45 ns, eliminating the need for speed reducing WAIT states on high-performance
microprocessor systems.
Atmel’s scaled CMOS technology provides low-active power consumption, and fast
programming. Power consumption is typically only 8 mA in Active Mode and less than
10
µA
in Standby.
(continued)
Pin Configurations
Pin Name
A0 - A14
O0 - O7
CE
OE
NC
Function
Addresses
Outputs
Chip Enable
Output Enable
No Connect
PDIP SOIC Top View
,
VPP
A12
A7
A6
A5
A4
A3
A2
A1
A0
O0
O1
O2
GND
1
2
3
4
5
6
7
8
9
10
11
12
13
14
28
27
26
25
24
23
22
21
20
19
18
17
16
15
VCC
A14
A13
A8
A9
A11
OE
A10
CE
O7
O6
O5
O4
O3
256K EPROM
PLCC Top View
TSOP Top View
Type 1
A8
A9
A11
NC
OE
A10
CE
O7
O6
OE
A11
A9
A8
A13
A14
VCC
VPP
A12
A7
A6
A5
A4
A3
22
23
24
25
26
27
28
1
2
3
4
5
6
7
21
20
19
18
17
16
15
14
13
12
11
10
9
8
A10
CE
O7
O6
O5
O4
O3
GND
O2
O1
O0
A0
A1
A2
A7
A12
VPP
NC
VCC
A14
A13
O1
O2
GND
NC
O3
O4
O5
14
15
16
17
18
19
20
A6
A5
A4
A3
A2
A1
A0
NC
O0
5
6
7
8
9
10
11
12
13
4
3
2
1
32
31
30
29
28
27
26
25
24
23
22
21
Note:
PLCC Package Pins 1 and
17 are DON’T CONNECT.
Rev. 0014H–07/98
1
The AT27C256R is available in a choice of industry stan-
dard JEDEC-approved one time programmable (OTP)
plastic DIP, PLCC, SOIC, and TSOP packages. All devices
feature two-line control (CE, OE) to give designers the flex-
ibility to prevent bus contention.
With 32K byte storage capability, the AT27C256R allows
firmware to be stored reliably and to be accessed by the
system without the delays of mass storage media.
Atmel’s 27C256R has additional features to ensure high
quality and efficient production use. The Rapid™ Program-
ming Algorithm reduces the time required to program the
part and guarantees reliable programming. Programming
time is typically only 100 µs/byte. The Integrated Product
Identification Code electronically identifies the device and
manufacturer. This feature is used by industry standard
programming equipment to select the proper programming
algorithms and voltages.
System Considerations
Switching between active and standby conditions via the
Chip Enable pin may produce transient voltage excursions.
Unless accommodated by the system design, these tran-
sients may exceed data sheet limits, resulting in device
non-conformance. At a minimum, a 0.1 µF high frequency,
low inherent inductance, ceramic capacitor should be uti-
lized for each device. This capacitor should be connected
between the V
CC
and Ground terminals of the device, as
close to the device as possible. Additionally, to stabilize the
supply voltage level on printed circuit boards with large
EPROM arrays, a 4.7 µF bulk electrolytic capacitor should
be utilized, again connected between the V
CC
and Ground
terminals. This capacitor should be positioned as close as
possible to the point where the power supply is connected
to the array.
Block Diagram
2
AT27C256R
AT27C256R
Absolute Maximum Ratings*
Temperature Under Bias ................................ -55°C to +125°C
Storage Temperature ..................................... -65°C to +150°C
Voltage on Any Pin with
Respect to Ground .........................................-2.0V to +7.0V
(1)
Voltage on A9 with
Respect to Ground ......................................-2.0V to +14.0V
(1)
V
PP
Supply Voltage with
Respect to Ground .......................................-2.0V to +14.0V
(1)
Note:
1.
Minimum voltage is -0.6V dc which may undershoot to -2.0V for pulses of less than 20 ns.Maximum output pin voltage is
V
CC
+ 0.75V dc which may overshoot to +7.0 volts for pulses of less than 20 ns.
*NOTICE:
Stresses beyond those listed under “Absolute Maxi-
mum Ratings” may cause permanent damage to
the device. This is a stress rating only and func-
tional operation of the device at these or any other
conditions beyond those indicated in the opera-
tional sections of this specification is not implied.
Exposure to absolute maximum rating conditions
for extended periods may affect device reliability.
Operating Modes
Mode\Pin
Read
Output Disable
Standby
Rapid Program
(2)
PGM Verify
(2)
Optional PGM Verify
(2)
PGM Inhibit
(2)
Product Identification
(4)
Notes:
1. X can be V
IL
or V
IH
.
2. Refer to Programming Characteristics.
3. V
H
= 12.0
±
0.5V.
4. Two identifier bytes may be selected. All Ai inputs are held low (V
IL
), except A9 which is set to V
H
and A0 which is toggled low
(V
IL
) to select the Manufacturer’s Identification byte and high (V
IH
) to select the Device Code byte.
CE
V
IL
V
IL
V
IH
V
IL
X
(1)
V
IL
V
IH
V
IL
OE
V
IL
V
IH
X
(1)
V
IH
V
IL
V
IL
V
IH
V
IL
Ai
Ai
X
(1)
X
(1)
Ai
Ai
Ai
X
(1)
A9 = V
H(3)
A0 = V
IH
or V
IL
A1 - A14 = V
IL
V
PP
V
CC
V
CC
V
CC
V
PP
V
PP
V
CC
V
PP
V
CC
Outputs
D
OUT
High Z
High Z
D
IN
D
OUT
D
OUT
High Z
Identification Code
3
DC and AC Operating Conditions for Read Operation
AT27C256R
-45
Com.
Operating
Temp. (Case)
V
CC
Supply
Ind.
Auto.
5V
±
10%
5V
±
10%
0°C - 70°C
-40°C - 85°C
-55
0°C - 70°C
-40°C - 85°C
-70
0°C - 70°C
-40°C - 85°C
-40°C - 125°C
5V
±
10%
-90
0°C - 70°C
-40°C - 85°C
-40°C - 125°C
5V
±
10%
-12
0°C - 70°C
-40°C - 85°C
-40°C - 125°C
5V
±
10%
-15
0°C - 70°C
-40°C - 85°C
-40°C - 125°C
5V
±
10%
DC and Operating Characteristics for Read Operation
Symbol
I
LI
Parameter
Input Load Current
Condition
Com., Ind.
V
IN
= 0V to V
CC
Auto.
Com., Ind.
I
LO
I
PP1(2)
I
SB
I
CC
V
IL
V
IH
V
OL
V
OH
Output Leakage Current
V
PP(1)
Read/Standby Current
V
CC(1)
Standby Current
V
CC
Active Current
Input Low Voltage
Input High Voltage
Output Low Voltage
Output High Voltage
I
OL
= 2.1 mA
I
OH
= -400 µA
2.4
V
OUT
= 0V to V
CC
V
PP
= V
CC
I
SB1
(CMOS), CE = V
CC
±
0.3V
I
SB2
(TTL), CE = 2.0 to V
CC
+ 0.5V
f = 5 MHz, I
OUT
= 0 mA, E = V
IL
-0.6
2.0
Auto.
Min
Max
±1
±5
±5
±10
10
100
1
20
0.8
V
CC
+ 0.5
0.4
Units
µA
µA
µA
µA
µA
µA
mA
mA
V
V
V
V
Notes:
1. V
CC
must be applied simultaneously with or before V
PP
, and removed simultaneously with or after V
PP
..
2. V
PP
may be connected directly to V
CC
, except during programming. The supply current would then be the sum of I
CC
and I
PP
.
.
AC Characteristics for Read Operation
AT27C256R
-45
Symbol
t
ACC(3)
t
CE(2)
t
OE(2)(3)
t
DF(4)(5)
t
OH
Parameter
Address to Output Delay
CE to Output Delay
OE to Output Delay
Condition
CE = OE = V
IL
OE = V
IL
CE = V
IL
Min
Max
45
45
20
20
7
7
Min
-55
Max
55
55
25
20
7
Min
-70
Max
70
70
30
25
0
Min
-90
Max
90
90
30
25
0
Min
-12
Max
120
120
35
30
0
Min
-15
Max
150
150
40
35
Units
ns
ns
ns
ns
ns
OE or CE High to Output
Float, whichever occurred first
Output Hold from Address, CE or OE,
whichever occurred first
Note:
2, 3, 4, 5. - see AC Waveforms for Read Operation.
4
AT27C256R
AT27C256R
AC Waveforms for Read Operation
(1)
Notes:
1.
Timing measurement reference level is 1.5V for -45 and -55 devices. Input AC drive levels are V
IL
= 0.0V and V
IH
= 3.0V.
Timing measurement reference levels for all other speed grades are V
OL
= 0.8V and V
OH
= 2.0V. Input AC drive levels are
V
IL
= 0.45V and V
IH
= 2.4V.
OE may be delayed up to t
CE
- t
OE
after the falling edge of CE without impact on t
CE
.
OE may be delayed up to t
ACC
- t
OE
after the address is valid without impact on t
ACC
.
This parameter is only sampled and is not 100% tested.
Output float is defined as the point when data is no longer driven.
2.
3.
4.
5.
Input Test Waveforms and
Measurement Levels
For -45 and -55 devices only:
Output Test Load
t
R
, t
F
< 5 ns (10% to 90%)
For -70, -90, -12, and -15 devices:
Note:
C
L
= 100 pF including jig
capacitance, except for
the -45 and -55 devices,
where C
L
= 30 pF.
t
R
, t
F
< 20 ns (10% to 90%)
Pin Capacitance
f = 1 MHz, T = 25°C
(1)
Symbol
C
IN
C
OUT
Note:
Typ
4
8
Max
6
12
Units
pF
pF
Conditions
V
IN
= 0V
V
OUT
= 0V
1. Typical values for nominal supply voltage. This parameter is only sampled and is not 100% tested.
5
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