1
Features
Fast Read Access Time - 45 ns
Low-Power CMOS Operation
100 A 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
RapidTM Programming Algorithm - 100 s/byte (typical)
CMOS and TTL Compatible Inputs and Outputs
Integrated Product Identification Code
Commercial, Industrial and Automotive Temperature Ranges
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
A in Standby.
256K (32K x 8)
OTP EPROM
AT27C256R
Rev. 0014H07/98
256K EPROM
Pin Configurations
Pin Name
Function
A0 - A14
Addresses
O0 - O7
Outputs
CE
Chip Enable
OE
Output Enable
NC
No Connect
TSOP Top View
Type 1
1
2
3
4
5
6
7
21
20
19
18
17
16
15
14
13
12
11
10
9
8
VPP
A12
A7
A6
A5
A4
A3
A10
CE
O7
O6
O5
O4
O3
GND
O2
O1
O0
A0
A1
A2
OE
A11
A9
A8
A13
A14
VCC
22
23
24
25
26
27
28
PLCC Top View
Note:
PLCC Package Pins 1 and
17 are DON'T CONNECT.
5
6
7
8
9
10
11
12
13
29
28
27
26
25
24
23
22
21
A6
A5
A4
A3
A2
A1
A0
NC
O0
A8
A9
A11
NC
OE
A10
CE
O7
O6
4
3
2
1
32
31
30
14
15
16
17
18
19
20
O1
O2
GND
NC
O3
O4
O5
A7
A12
VPP
NC
VCC
A14
A13
(continued)
PDIP, SOIC Top View
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
VPP
A12
A7
A6
A5
A4
A3
A2
A1
A0
O0
O1
O2
GND
VCC
A14
A13
A8
A9
A11
OE
A10
CE
O7
O6
O5
O4
O3
AT27C256R
2
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 RapidTM Program-
ming Algorithm reduces the time required to program the
part and guarantees reliable programming. Programming
time is typically only 100 s/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 F 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 F 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
AT27C256R
3
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.
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.
Absolute Maximum Ratings*
Temperature Under Bias ................................ -55C to +125C
*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.
Storage Temperature ..................................... -65C to +150C
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)
Operating Modes
Mode\Pin
CE
OE
Ai
V
PP
Outputs
Read
V
IL
V
IL
Ai
V
CC
D
OUT
Output Disable
V
IL
V
IH
X
(1)
V
CC
High Z
Standby
V
IH
X
(1)
X
(1)
V
CC
High Z
Rapid Program
(2)
V
IL
V
IH
Ai
V
PP
D
IN
PGM Verify
(2)
X
(1)
V
IL
Ai
V
PP
D
OUT
Optional PGM Verify
(2)
V
IL
V
IL
Ai
V
CC
D
OUT
PGM Inhibit
(2)
V
IH
V
IH
X
(1)
V
PP
High Z
Product Identification
(4)
V
IL
V
IL
A9 = V
H
(3)
A0 = V
IH
or V
IL
A1 - A14 = V
IL
V
CC
Identification Code
AT27C256R
4
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
.
.
Note:
2, 3, 4, 5. - see AC Waveforms for Read Operation.
DC and AC Operating Conditions for Read Operation
AT27C256R
-45
-55
-70
-90
-12
-15
Operating
Temp. (Case)
Com.
0
C - 70
C
0
C - 70
C
0
C - 70
C
0
C - 70
C
0
C - 70
C
0
C - 70
C
Ind.
-40
C - 85
C
-40
C - 85
C
-40
C - 85
C
-40
C - 85
C
-40
C - 85
C
-40
C - 85
C
Auto.
-40
C - 125
C
-40
C - 125
C
-40
C - 125
C
-40
C - 125
C
V
CC
Supply
5V
10%
5V
10%
5V
10%
5V
10%
5V
10%
5V
10%
DC and Operating Characteristics for Read Operation
Symbol
Parameter
Condition
Min
Max
Units
I
LI
Input Load Current
V
IN
= 0V to V
CC
Com., Ind.
1
A
Auto.
5
A
I
LO
Output Leakage Current
V
OUT
= 0V to V
CC
Com., Ind.
5
A
Auto.
10
A
I
PP1
(2)
V
PP
(1)
Read/Standby Current
V
PP
= V
CC
10
A
I
SB
V
CC
(1)
Standby Current
I
SB1
(CMOS), CE = V
CC
0.3V
100
A
I
SB2
(TTL), CE = 2.0 to V
CC
+ 0.5V
1
mA
I
CC
V
CC
Active Current
f = 5 MHz, I
OUT
= 0 mA, E = V
IL
20
mA
V
IL
Input Low Voltage
-0.6
0.8
V
V
IH
Input High Voltage
2.0
V
CC
+ 0.5
V
V
OL
Output Low Voltage
I
OL
= 2.1 mA
0.4
V
V
OH
Output High Voltage
I
OH
= -400
A
2.4
V
AC Characteristics for Read Operation
Symbol
Parameter
Condition
AT27C256R
Units
-45
-55
-70
-90
-12
-15
Min
Max
Min
Max
Min
Max
Min
Max
Min
Max
Min
Max
t
ACC
(3)
Address to Output Delay
CE = OE = V
IL
45
55
70
90
120
150
ns
t
CE
(2)
CE to Output Delay
OE = V
IL
45
55
70
90
120
150
ns
t
OE
(2)(3)
OE to Output Delay
CE = V
IL
20
25
30
30
35
40
ns
t
DF
(4)(5)
OE or CE High to Output
Float, whichever occurred first
20
20
25
25
30
35
ns
t
OH
Output Hold from Address, CE or OE,
whichever occurred first
7
7
7
0
0
0
ns
AT27C256R
5
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.
2.
OE may be delayed up to t
CE
- t
OE
after the falling edge of CE without impact on t
CE
.
3.
OE may be delayed up to t
ACC
- t
OE
after the address is valid without impact on t
ACC
.
4.
This parameter is only sampled and is not 100% tested.
5.
Output float is defined as the point when data is no longer driven.
Input Test Waveforms and
Measurement Levels
Output Test Load
Note:
1. Typical values for nominal supply voltage. This parameter is only sampled and is not 100% tested.
t
R
, t
F
< 5 ns (10% to 90%)
For -45 and -55 devices only:
t
R
, t
F
< 20 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.
Pin Capacitance
f = 1 MHz, T = 25C
(1)
Symbol
Typ
Max
Units
Conditions
C
IN
4
6
pF
V
IN
= 0V
C
OUT
8
12
pF
V
OUT
= 0V
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