Features
•Fast read access time – 45ns
•Low-power CMOS operation
– 100µA max standby
– 20mA max active at 5MHz
•JEDEC standard packages
– 28-lead PDIP
– 32-lead PLCC
•5V±10% supply
•High reliability CMOS technology
– 2,000V ESD protection
– 200mA latchup immunity
•Rapid programming algorithm – 100µs/byte (typical)
•CMOS- and TTL-compatible inputs and outputs
•Integrated product identification code
•Industrial and automotive temperature ranges
•Green (Pb/halide-free) packaging option
1. Description
The Atmel® AT27C256R is a low-power, high-performance, 262,144-bit, one-time pro-
grammable, read-only memory (OTP EPROM) organized as 32K by 8 bits. It requires only
one 5V power supply in normal read mode operation. Any byte can be accessed in less than
45ns, eliminating the need for speed reducing WAIT states on high-performance micropro-
cessor systems.
The Atmel scaled CMOS technology provides low active power consumption and fast pro-
gramming. Power consumption is typically only 8mA in active mode and less than 10µA in
standby mode.
The AT27C256R is available in a choice of industry-standard, JEDEC-approved, one-time
programmable (OTP) PDIP and PLCC packages. All devices 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.
The AT27C256R has additional features to ensure high quality and efficient production use.
The rapid programming algorithm reduces the time required to program the part and guar-
antees reliable programming. Programming time is typically only 100µs/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 pro-
gramming algorithms and voltages.
256K (32K x 8)
One-time
Programmable,
Read-only Memory
Atmel AT27C256R
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Atmel AT27C256R
2. Pin configurations
3. 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 transients may exceed datasheet limits, resulting in device non-conformance.
At a minimum, a 0.1µF, high-frequency, low inherent inductance, ceramic capacitor should be utilized for each device. This
capacitor should be connected between the VCC 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 4.7µF bulk electrolytic
capacitor should be utilized, again connected between the VCC and ground terminals. This capacitor should be positioned as
close as possible to the point where the power supply is connected to the array.
Figure 3-1. Block diagram
Pin name Function
A0 - A14 Addresses
O0 - O7 Outputs
CE Chip enable
OE Output enable
NC No 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
Note: PLCC package pins 1
and 17 are “don’t
connect”
32-lead PLCC
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
28-lead PDIP
Top view
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Atmel AT27C256R
4. Absolute maximum ratings*
Note: 1. Minimum voltage is -0.6V DC, which may undershoot to -2.0V for pulses of less than 20ns. Maximum output pin voltage is
VCC + 0.75V DC, which may overshoot to +7.0V for pulses of less than 20ns.
5. DC and AC characteristics
Table 5-1. Operating Modes
Notes: 1. X can be VIL or VIH.
2. Refer to programming characteristics.
3. VH = 12.0 ± 0.5V.
4. Two identifier bytes may be selected. All Ai inputs are held low (VIL), except A9, which is set to VH, and A0, which is tog-
gled low (VIL) to select the manufacturer’s identification byte and high (VIH) to select the device code byte.
Table 5-2. DC and AC operating conditions for read operation
Temperature under bias . . . . . . . . . . . . . .-55°C to +125°C *NOTICE: Stresses beyond 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 these or any other conditions
beyond those indicated in the operational sections of
this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may
affect device reliability.
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)
VPP supply voltage with
respect to ground . . . . . . . . . . . . . . . . . . -2.0V to +14.0V(1)
Mode/Pin CE OE Ai VPP Outputs
Read VIL VIL Ai VCC DOUT
Output disable VIL VIH X
(1) VCC High Z
Standby VIH X
(1) X
(1) VCC High Z
Rapid program(2) VIL VIH Ai VPP DIN
PGM verify(2) X
(1) VIL Ai VPP DOUT
Optional PGM verify(2) VIL VIL Ai VCC DOUT
PGM inhibit(2) VIH VIH X(1) VPP High Z
Product identification(4) VIL VIL
A9 = VH(3)
A0 = VIH or VIL
A1 - A14 = VIL
VCC Identification code
Atmel AT27C256R
-45 -70
Operating temp. (case) Ind. -40C - 85C -40C - 85C
Auto. -40C - 125C
VCC supply 5V ±10% 5V ±10%
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Atmel AT27C256R
Table 5-3. DC and operating characteristics for read operation
Notes: 1. VCC must be applied simultaneously with or before VPP, and removed simultaneously with or after VPP.
2. VPP may be connected directly to VCC, except during programming. The supply current would then be the sum of ICC and
IPP.
Table 5-4. AC characteristics for read operation
Note: 1. See AC waveforms for read operation.
Symbol Parameter Condition Min Max Units
ILI Input load current VIN = 0V to VCC
Ind. ±1 µA
Auto. ±5 µA
ILO Output leakage current VOUT = 0V to VCC
Ind. ±5 µA
Auto. ±10 µA
IPP1(2) VPP(1) read/standby current VPP = VCC 10 µA
ISB VCC(1) standby current
ISB1 (CMOS), CE = VCC 0.3V 100 µA
ISB2 (TTL), CE = 2.0 to VCC + 0.5V 1 mA
ICC VCC active current f = 5MHz, IOUT = 0mA, E = VIL 20 mA
VIL Input low voltage -0.6 0.8 V
VIH Input high voltage 2.0 VCC + 0.5 V
VOL Output low voltage IOL = 2.1mA 0.4 V
VOH Output high voltage IOH = -400µA 2.4 V
Symbol Parameter Condition
Atmel AT27C256R
Units
-45 -70
Min Max Min Max
tACC(1) Address to output delay CE = OE = VIL 45 70 ns
tCE(1) CE to output delay OE = VIL 45 70 ns
tOE(1) OE to output delay CE = VIL 20 30 ns
tDF(1) OE or CE high to output float, whichever occurred first 20 25 ns
tOH
Output hold from address, CE or OE, whichever occurred
first 77 ns
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Atmel AT27C256R
Figure 5-1. AC waveforms for read operation(1)
Notes: 1. Timing measurement reference level is 1.5V for -45 devices. Input AC drive levels are VIL = 0.0V and VIH = 3.0V. Timing
measurement reference levels for all other speed grades are VOL = 0.8V and VOH = 2.0V. Input AC drive levels are VIL =
0.45V and VIH = 2.4V.
2. OE may be delayed up to tCE - tOE after the falling edge of CE without impact on tCE.
3. OE may be delayed up to tACC - tOE after the address is valid without impact on tACC.
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.
Figure 5-2. Input test waveforms and measurement levels
tR, tF < 5ns (10% to 90%)
For -45 devices only:
tR, tF < 20ns (10% to 90%)
For -70 devices:
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Atmel AT27C256R
Figure 5-3. Output test load
Note: 1. CL = 100pF including jig capacitance, except for the -45 devices, where CL = 30pF.
Table 5-5. Pin capacitance
Note: 1. Typical values for nominal supply voltage. This parameter is only sampled, and is not 100% tested.
Figure 5-4. Programming Waveforms(1)
Notes: 1. The input timing reference is 0.8V for VIL and 2.0V for VIH.
2. tOE and tDFP are characteristics of the device, but must be accommodated by the programmer.
3. When programming the Atmel AT27C256R, a 0.1µF capacitor is required across VPP and ground to suppress spurious volt-
age transients.
f = 1MHz, T = 25°C(1)
Symbol Typ Max Units Conditions
CIN 4 6 pF VIN = 0V
COUT 812pFV
OUT = 0V
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Atmel AT27C256R
Table 5-6. DC programming characteristics
Table 5-7. AC programming characteristics
Notes: 1. VCC must be applied simultaneously with or before VPP and removed simultaneously with or after VPP.
2. This parameter is only sampled, and is not 100% tested. Output float is defined as the point where data is no longer driven.
See timing diagram.
3. Program pulse width tolerance is 100µs 5%.
Table 5-8. The Atmel AT27C256R integrated product identification code
TA = 25 5°C, VCC = 6.5 0.25V, VPP = 13.0 0.25V
Symbol Parameter Test Conditions
Limits
UnitsMin Max
ILI Input load current VIN = VIL,VIH ±10 µA
VIL Input low level -0.6 0.8 V
VIH Input high level 2.0 VCC + 1 V
VOL Output low volt IOL = 2.1mA 0.4 V
VOH Output high volt IOH = -400µA 2.4 V
ICC2 VCC supply current (program and verify) 25 mA
IPP2 VPP current CE = VIL 25 mA
VID A9 product identification voltage 11.5 12.5 V
TA = 25 5°C, VCC = 6.5 0.25V, VPP = 13.0 0.25V
Symbol Parameter Test conditions(1)
Limits
UnitsMin Max
tAS Address setup time
Input rise and fall times
(10% to 90%) 20ns
Input pulse levels
0.45V to 2.4V
Input timing reference level
0.8V to 2.0V
Output timing reference level
0.8V to 2.0V
2µs
tOES OE setup time 2 µs
tDS Data setup time 2 µs
tAH Address hold time 0 µs
tDH Data hold time 2 µs
tDFP OE high to output float delay(2) 0 130 ns
tVPS VPP setup time 2 µs
tVCS VCC setup time 2 µs
tPW CE program pulse width(3) 95 105 µs
tOE Data valid from OE(2) 150 ns
tPRT VPP pulse rise time during programming 50 ns
Codes
Pins Hex
dataA0 O7 O6 O5 O4 O3 O2 O1 O0
Manufacturer 0 0 0 011110 1E
Device type 1 1 0 001100 8C
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Atmel AT27C256R
6. Rapid programming algorithm
A 100µs CE pulse width is used to program. The address is set to the first location. VCC is raised to 6.5V and VPP is raised to
13.0V. Each address is first programmed with one 100µs CE pulse without verification. Then a verification/reprogramming
loop is executed for each address. In the event a byte fails to pass verification, up to 10 successive 100µs pulses are
applied with a verification after each pulse. If the byte fails to verify after 10 pulses have been applied, the part is
considered failed. After the byte verifies properly, the next address is selected until all have been checked. VPP is then
lowered to 5.0V and VCC to 5.0V. All bytes are read again and compared with the original data to determine if the device
passes or fails.
Figure 6-1. Rapid programming algorithm
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Atmel AT27C256R
7. Ordering information
Green package (Pb/halide-free)
tACC
(ns)
ICC (mA)
Atmel ordering code Package Lead finish Operation rangeActive Standby
45 20 0.1 AT27C256R-45JU
AT27C256R-45PU
32J
28P6
Matte tin
Matte tin
Industrial
(-40C to 85C)
70 20 0.1 AT27C256R-70JU
AT27C256R-70PU
32J
28P6
Matte tin
Matte tin
Industrial
(-40C to 85C)
Package type
32J 32-lead, plastic, J-leaded chip carrier (PLCC)
28P6 28-lead, 0.600" wide, plastic, dual inline package (PDIP)
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Atmel AT27C256R
8. Packaging information
32J – PLCC
DRAWING NO. REV.
TITLE
32J, 32-lead, plastic J-leaded chip carrier (PLCC) B
32J
10/04/01
1.14(0.045) X 45° PIN NO. 1
IDENTIFIER
1.14(0.045) X 45°
0.51(0.020)MAX
0.318(0.0125)
0.191(0.0075)
A2
45° MAX (3X)
A
A1
B1 E2
B
e
E1 E
D1
D
D2
COMMON DIMENSIONS
(Unit of measure = mm)
SYMBOL MIN NOM MAX NOTE
Package drawing contact:
packagedrawings@atmel.com
Notes: 1. This package conforms to JEDEC reference MS-016, variation AE.
2. Dimensions D1 and E1 do not include mold protrusion.
Allowable protrusion is .010"(0.254mm) per side. Dimension D1
and E1 include mold mismatch and are measured at the extreme
material condition at the upper or lower parting line.
3. Lead coplanarity is 0.004" (0.10mm) maximum.
A 3.175 – 3.556
A1 1.524 – 2.413
A2 0.381 – –
D 12.319 – 12.573
D1 11.354 – 11.506 Note 2
D2 9.906 – 10.922
E 14.859 – 15.113
E1 13.894 – 14.046 Note 2
E2 12.471 – 13.487
B 0.660 – 0.813
B1 0.330 – 0.533
e 1.270 TYP
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0014O–EPROM–10/11
Atmel AT27C256R
28P6 – PDIP
TITLE DRAWING NO. REV.
28P6, 28-lead (0.600"/15.24mm wide) plastic dual
inline package (PDIP) B
28P6
09/28/01
PIN
1
E1
A1
B
REF
E
B1
C
L
SEATING PLANE
A
0º ~ 15º
D
e
eB
COMMON DIMENSIONS
(Unit of Measure = mm)
SYMBOL MIN NOM MAX NOTE
A – – 4.826
A1 0.381 – –
D 36.703 – 37.338 Note 2
E 15.240 – 15.875
E1 13.462 – 13.970 Note 2
B 0.356 – 0.559
B1 1.041 – 1.651
L 3.048 – 3.556
C 0.203 – 0.381
eB 15.494 – 17.526
e 2.540 TYP
Notes: 1. This package conforms to JEDEC reference MS-011, variation AB
2. Dimensions D and E1 do not include mold flash or protrusion
mold flash or protrusion shall not exceed 0.25mm (0.010")
Package drawing contact:
packagedrawings@atmel.com
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0014O–EPROM–10/11
Atmel AT27C256R
9. Revision history
Doc. rev. Date Comments
0014O 10/2011 Correct pinouts
0014N 04/2011 Remove TSOP and SOIC packages
Add lead finish to ordering information
0014M 12/2007
Atmel Corporation
2325 Orchard Parkway
San Jose, CA 95131
USA
Tel: (+1) (408) 441-0311
Fax: (+1) (408) 487-2600
www.atmel.com
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BEA Tower, Millennium City 5
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GERMANY
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Chuo-ku, Tokyo 104-0033
JAPAN
Tel: (+81) (3) 3523-3551
Fax: (+81) (3) 3523-7581
© 2011 Atmel Corporation. All rights reserved. / Rev.: 0014O–EPROM–10/11
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