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
A in Standby.
(continued)
256K (32K x 8)
OTP
CMOS
EPROM
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
Rapid
TM
Programming Algorithm - 100
s/byte (typical)
CMOS and TTL Compatible Inputs and Outputs
Integrated Product Identification Code
Commercial and Industrial Temperature Ranges
Pin Configurations
Pin Name
Function
A0 - A14
Addresses
O0 - O7
Outputs
CE
Chip Enable
OE
Output Enable
NC
No Connect
PDIP, SOIC Top View
Note: PLCC Package Pins 1 and
17 are DON'T CONNECT.
PLCC Top View
TSOP Top View
Type 1
0014G
AT27C256R
3-125
The AT27C256R is available in a choice of industry stand-
ard JEDEC-approved one time programmable (OTP)
plastic DIP, PLCC, SOIC, and TSOP packages. All de-
vices feature two-line control (CE, OE) to give designers
the flexibility 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
TM
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 program-
ming algorithms and voltages.
Description (Continued)
Switching between active and standby conditions via the
Chip Enable pin may produce transient voltage excur-
sions. Unless accommodated by the system design, these
transients may exceed data sheet limits, resulting in de-
vice non-conformance. At a minimum, a 0.1
F high fre-
quency, low inherent inductance, ceramic capacitor
should be utilized 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 posi-
tioned as close as possible to the point where the power
supply is connected to the array.
System Considerations
3-126
AT27C256R
Block Diagram
Temperature Under Bias ................ -55C to +125C
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)
*NOTICE: Stresses beyond those listed under "Absolute Maxi-
mum Ratings" may cause permanent damage to the device.
This is a stress rating only and functional operation of the
device at these or any other conditions beyond those indi-
cated in the operational sections of this specification is not
implied. Exposure to absolute maximum rating conditions
for extended periods may affect device reliability.
Note: 1. Minimum voltage is -0.6V dc which may undershoot
to -2.0V for pulses of less than 20 ns. Maximum out-
put pin voltage is V
CC
+ 0.75V dc which may over-
shoot to +7.0V for pulses of less than 20 ns.
Absolute Maximum Ratings*
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
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 Identi-
fication byte and high (V
IH
) to select the Device Code byte.
AT27C256R
3-127
AC Characteristics for Read Operation
AT27C256R
-45
-55
-70
-90
-12
-15
Symbol
Parameter
Condition
Min
Max
Min
Max
Min
Max
Min
Max
Min
Max
Min
Max
Units
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
Notes:
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.
0C - 70C
0C - 70C
0C - 70C
0C - 70C
0C - 70C
0C - 70C
Ind. -40C - 85C
-40C - 85C
-40C - 85C
-40C - 85C
-40C - 85C
-40C - 85C
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
1
A
I
LO
Output Leakage Current
V
OUT
= 0V to V
CC
5
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,
CE = 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
Notes: 1. V
CC
must be applied simultaneously or before V
PP
,
and removed simultaneously or after V
PP
.
2. V
PP
may be connected directly to V
CC
, except during program-
ming. The supply current would then be the sum of I
CC
and I
PP
.
3-128
AT27C256R
Pin Capacitance
(f = 1MHz, T = 25C)
(1)
Typ
Max
Units
Conditions
C
IN
4
6
pF
V
IN
= 0V
C
OUT
8
12
pF
V
OUT
= 0V
Note:
1. Typical values for nominal supply voltage. This parameter is only sampled and is not 100% tested.
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 refer-
ence 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
t
R
, t
F
< 5 ns (10% to 90%)
For -45 and -55 devices only:
For -70, -90, -12, and -15 devices:
Output Test Load
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%)
AT27C256R
3-129
PDF 
ZIP