ATMEL AT27C256R User Manual

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 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

• Industrial and Automotive Temperature Ranges

• Green (Pb/Halide-free) Packaging Option

1. Description

The AT27C256R is a low-power, high-performance 262,144-bit one-time programma­ble 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.

256K (32K x 8)
OTP EPROM

AT27C256R

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.

The AT27C256R is available in a choice of industry-standard JEDEC-approved one
time programmable (OTP) plastic DIP, PLCC, SOIC, and TSOP packages. All devices
feature two-line control (CE
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 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 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.

, OE) to give designers the flexibility to prevent bus

0014K–EPROM–10/05

2. Pin Configurations

Pin Name Function

A0 - A14 Addresses

O0 - O7 Outputs

CE

Chip Enable

OE

Output Enable

NC No Connect

2.1 28-lead 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

VCC

27

A14

26

A13

25

A8

24

A9

23

A11

22

OE

21

A10

20

CE

19

O7

18

O6

17

O5

16

O4

15

O3

2.3 28-lead TSOP Top View – Type 1

2.2 32-lead PLCC Top View

OE

A11

A9

A8
A13
A14

VCC

VPP

A12

A7

A6

A5

A4

A3

1
2
3
4
5
6

7
8
9
10
11
12
13
14

28

A10

27

CE

26

O7

25

O6

24

O5

23

O4

22

O3

21

GND

20

O2

19

O1

18

O0

17

A0

16

A1

15

A2

A7

A12

VPPNCVCC

A14

A13

432

1

O2

GND

323130

O3O4O5

NC

29

A8

28

A9

27

A11

26

NC

25

OE

24

A10

23

CE

22

O7

21

O6

A6
A5
A4
A3
A2
A1
A0

NC

O0

5
6
7
8
9
10
11
12
13

14151617181920

O1

Note: PLCC Package Pins 1 and 17 are Don’t Connect.

2

AT27C256R

0014K–EPROM–10/05

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 0.1 µF high
frequency, low inherent inductance, ceramic capacitor should be utilized for each device. This
capacitor should be connected between the V
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
close as possible to the point where the power supply is connected to the array.

4. Block Diagram

AT27C256R

and Ground terminals of the device, as close

CC

and Ground terminals. This capacitor should be positioned as

CC

5. 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

Voltage on A9 with

Respect to Ground ......................................-2.0V to +14.0V

VPP Supply Voltage with

Respect to Ground .......................................-2.0V to +14.0V

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

+ 0.75V dc which may overshoot to +7.0 volts for pulses of less than 20 ns.

CC

(1)

(1)

(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 indicated in the opera­tional sections of this specification is not implied.
Exposure to absolute maximum rating conditions
for extended periods may affect device reliability.

0014K–EPROM–10/05

3

6. Operating Modes

Mode/Pin CE OE Ai V

Read V

Output Disable V

Standby V

Rapid Program

PGM Verify

Optional PGM Verify

PGM Inhibit

Product Identification

(2)

(2)

(2)

(2)

(4)

X

IL

IL

IH

V

IL

(1)

V

IL

V

IH

V

IL

V

V

X

V

V

V

V

V

IL

IH

(1)

IH

IL

IL

IH

IL

Ai V

(1)

X

(1)

X

Ai V

Ai V

Ai V

(1)

X

A9 = V

(3)

H

A0 = VIH or VIL
A1 - A14 = V

IL

Notes: 1. X can be VIL or VIH.

2. Refer to Programming Characteristics.

= 12.0 ± 0.5V.

3. V

H

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 toggled
low (V

) to select the Manufacturer’s Identification byte and high (VIH) to select the Device Code byte.

IL

7. DC and AC Operating Conditions for Read Operation

AT27C256R

-45 -70

V

PP

CC

V

CC

V

CC

PP

PP

CC

V

PP

CC

Outputs

D

OUT

High Z

High Z

D

IN

D

OUT

D

OUT

High Z

Identification Code

Operating Temp. (Case) Ind. -40°C - 85°C-40°C - 85°C

Auto. -40°C - 125°C

V

Supply 5V ± 10% 5V ± 10%

CC

8. DC and Operating Characteristics for Read Operation

Symbol Parameter Condition Min Max Units

I

LI

I

LO

(2)

I

PP1

I

SB

I

CC

V

IL

V

IH

V

OL

V

OH

Notes: 1. V

2. V

Input Load Current VIN = 0V to V

Output Leakage Current V

(1)

V

Read/Standby Current VPP = V

PP

(1)

V

Standby Current

CC

= 0V to V

OUT

I

(CMOS), CE = VCC ± 0.3V 100 µA

SB1

I

(TTL), CE = 2.0 to V

SB2

VCC Active Current f = 5 MHz, I

CC

OUT

CC

CC

= 0 mA, E = V

Input Low Voltage -0.6 0.8 V

Input High Voltage 2.0 VCC + 0.5 V

Output Low Voltage IOL = 2.1 mA 0.4 V

Output High Voltage IOH = -400 µA 2.4 V

must be applied simultaneously with or before VPP, and removed simultaneously with or after VPP..

CC

may be connected directly to VCC, except during programming. The supply current would then be the sum of ICC and IPP.

PP

Ind. ±1 µA

Auto. ±5 µA

Ind. ±5 µA

Auto. ±10 µA

10 µA

+ 0.5V 1 mA

CC

IL

20 mA

4

AT27C256R

0014K–EPROM–10/05

.

9. AC Characteristics for Read Operation

Symbol Parameter Condition

(1)

t

ACC

(1)

t

CE

(1)

t

OE

(1)

t

DF

t

OH

Note: 1. See AC Waveforms for Read Operation.

Address to Output Delay CE = OE = V

CE to Output Delay OE = V

OE to Output Delay CE = V

IL

IL

OE or CE High to Output
Float, Whichever Occurred First

Output Hold from Address, CE or OE,
Whichever Occurred First

AT27C256R

AT27C256R

-45 -70

Min Max Min Max

IL

45 70 ns

45 70 ns

20 30 ns

20 25 ns

77 ns

Units

10. 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 mea-

surement reference levels for all other speed grades are V
and V

2. OE

3. OE

= 2.4V.

IH

may be delayed up to tCE - tOE after the falling edge of CE without impact on tCE.

may be delayed up to t

- tOE after the address is valid without impact on t

ACC

= 0.8V and VOH = 2.0V. Input AC drive levels are VIL = 0.45V

OL

.

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.

0014K–EPROM–10/05

5