Features
• Single 2.7V - 3.6V Supply
• Fast Read Access Time – 200 ns
• Automatic Page Write Operation
•
•
•
•
•
•
•
•
– Internal Address and Data Latches for 64 Bytes
– Internal Control Timer
Fast Write Cycle Times
– Page Write Cycle Time: 10 ms Maximum
– 1- to 64-byte Page Write Operation
Low Power Dissipation
– 15 mA Active Current
– 20 µA CMOS Standby Current
Hardware and Software Data Protection
Data Polling for End of Write Detection
High Reliability CMOS Technology
– Endurance: 10,000 Cycles
– Data Retention: 10 Years
JEDEC Approved Byte-wide Pinout
Industrial Temperature Ranges
Green (Pb/Halide-free) Packaging Option Only
256K (32K x 8)
Battery-Voltage
Parallel
EEPROMs
AT28BV256
1. Description
The AT28BV256 is a high-performance electrically erasable and programmable readonly memory. Its 256K of memory is organized as 32,768 words by 8 bits. Manufactured with Atmel’s advanced nonvolatile CMOS technology, the device offers access
times to 200 ns with power dissipation of just 54 mW. When the device is deselected,
the CMOS standby current is less than 200 µA.
The AT28BV256 is accessed like a Static RAM for the read or write cycle without the
need for external components. The device contains a 64-byte page register to allow
writing of up to 64 bytes simultaneously. During a write cycle, the addresses and 1 to
64 bytes of data are internally latched, freeing the address and data bus for other
operations. Following the initiation of a write cycle, the device will automatically write
the latched data using an internal control timer. The end of a write cycle can be
detected by Data polling of I/O7. Once the end of a write cycle has been detected a
new access for a read or write can begin.
Atmel’s AT28BV256 has additional features to ensure high quality and manufacturability. The device utilizes internal error correction for extended endurance and
improved data retention characteristics. An optional software data protection mechanism is available to guard against inadvertent writes. The device also includes an
extra 64 bytes of EEPROM for device identification or tracking.
0273K–PEEPR–2/09
2. Pin Configurations
2.2
Pin Name
Function
A0 - A14
Addresses
CE
Chip Enable
OE
Output Enable
WE
Write Enable
I/O0 - I/O7
Data Inputs/Outputs
NC
No Connect
DC
Don’t Connect
A14
A12
A7
A6
A5
A4
A3
A2
A1
A0
I/O0
I/O1
I/O2
GND
32-lead PLCC – Top View
2.3
29
28
27
26
25
24
23
22
21
14
15
16
17
18
19
20
5
6
7
8
9
10
11
12
13
A8
A9
A11
NC
OE
A10
CE
I/O7
I/O6
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
WE
A13
A8
A9
A11
OE
A10
CE
I/O7
I/O6
I/O5
I/O4
I/O3
28-lead TSOP – Top View
OE
A11
A9
A8
A13
WE
VCC
A14
A12
A7
A6
A5
A4
A3
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
A10
CE
I/O7
I/O6
I/O5
I/O4
I/O3
GND
I/O2
I/O1
I/O0
A0
A1
A2
I/O1
I/O2
GND
DC
I/O3
I/O4
I/O5
A6
A5
A4
A3
A2
A1
A0
NC
I/O0
4
3
2
1
32
31
30
A7
A12
A14
DC
VCC
WE
A13
2.1
28-lead SOIC – Top View
Note:
2
1. PLCC package pins 1 and 17 are Don’t Connect.
AT28BV256
0273K–PEEPR–2/09
AT28BV256
3. Block Diagram
4. Absolute Maximum Ratings*
Temperature under Bias ................................ -55°C to +125°C
Storage Temperature ..................................... -65°C to +150°C
All Input Voltages (including NC Pins)
with Respect to Ground ...................................-0.6V to +6.25V
All Output Voltages
with Respect to Ground .............................-0.6V to VCC + 0.6V
*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
Voltage on OE and A9
with Respect to Ground ...................................-0.6V to +13.5V
3
0273K–PEEPR–2/09
5. Device Operation
5.1
Read
The AT28BV256 is accessed like a Static RAM. When CE and OE are low and WE is high, the
data stored at the memory location determined by the address pins is asserted on the outputs.
The outputs are put in the high impedance state when either CE or OE is high. This dual-line
control gives designers flexibility in preventing bus contention in their system.
5.2
Byte Write
A low pulse on the WE or CE input with CE or WE low (respectively) and OE high initiates a write
cycle. The address is latched on the falling edge of CE or WE, whichever occurs last. The data is
latched by the first rising edge of CE or WE. Once a byte write has been started, it will automatically time itself to completion. Once a programming operation has been initiated and for the
duration of tWC, a read operation will effectively be a polling operation.
5.3
Page Write
The page write operation of the AT28BV256 allows 1 to 64 bytes of data to be written into the
device during a single internal programming period. A page write operation is initiated in the
same manner as a byte write; the first byte written can then be followed by 1 to 63 additional
bytes. Each successive byte must be written within 150 µs (tBLC) of the previous byte. If the tBLC
limit is exceeded the AT28BV256 will cease accepting data and commence the internal programming operation. All bytes during a page write operation must reside on the same page as
defined by the state of the A6 - A14 inputs. For each WE high to low transition during the page
write operation, A6 - A14 must be the same.
The A0 to A5 inputs are used to specify which bytes within the page are to be written. The bytes
may be loaded in any order and may be altered within the same load period. Only bytes which
are specified for writing will be written; unnecessary cycling of other bytes within the page does
not occur.
5.4
Data Polling
The AT28BV256 features Data Polling to indicate the end of a write cycle. During a byte or page
write cycle, an attempted read of the last byte written will result in the complement of the written
data to be presented on I/O7. Once the write cycle has been completed, true data is valid on all
outputs, and the next write cycle may begin. Data Polling may begin at anytime during the write
cycle.
5.5
Toggle Bit
In addition to Data Polling, the AT28BV256 provides another method for determining the end of
a write cycle. During the write operation, successive attempts to read data from the device will
result in I/O6 toggling between one and zero. Once the write has completed, I/O6 will stop toggling and valid data will be read. Reading the toggle bit may begin at any time during the write
cycle.
5.6
Data Protection
If precautions are not taken, inadvertent writes may occur during transitions of the host system
power supply. Atmel® has incorporated both hardware and software features that will protect the
memory against inadvertent writes.
4
AT28BV256
0273K–PEEPR–2/09
AT28BV256
5.6.1
Hardware Protection
Hardware features protect against inadvertent writes to the AT28BV256 in the following ways:
(a) VCC power-on delay – once VCC has reached 1.8V (typical) the device will automatically time
out 10 ms (typical) before allowing a write; (b) write inhibit – holding any one of OE low, CE high
or WE high inhibits write cycles; and (c) noise filter – pulses of less than 15 ns (typical) on the
WE or CE inputs will not initiate a write cycle.
5.6.2
Software Data Protection
A software-controlled data protection feature has been implemented on the AT28BV256. Software data protection (SDP) helps prevent inadvertent writes from corrupting the data in the
device. SDP can prevent inadvertent writes during power-up and power-down as well as any
other potential periods of system instability.
The AT28BV256 can only be written using the software data protection feature. A series of three
write commands to specific addresses with specific data must be presented to the device before
writing in the byte or page mode. The same three write commands must begin each write operation. All software write commands must obey the page mode write timing specifications. The
data in the 3-byte command sequence is not written to the device; the address in the command
sequence can be utilized just like any other location in the device.
Any attempt to write to the device without the 3-byte sequence will start the internal write timers.
No data will be written to the device; however, for the duration of tWC, read operations will effectively be polling operations.
5.7
Device Identification
An extra 64 bytes of EEPROM memory are available to the user for device identification. By raising A9 to 12V ± 0.5V and using address locations 7FC0H to 7FFFH the additional bytes may be
written to or read from in the same manner as the regular memory array.
5
0273K–PEEPR–2/09
6. DC and AC Operating Range
AT28BV256-20
Operating Temperature (Case)
-40°C - 85°C
VCC Power Supply
2.7V - 3.6V
7. Operating Modes
Mode
CE
OE
WE
I/O
Read
VIL
VIL
VIH
DOUT
Write(2)
VIL
VIH
VIL
DIN
High Z
Standby/Write Inhibit
(1)
VIH
X
X
Write Inhibit
X
X
VIH
Write Inhibit
X
VIL
X
Output Disable
X
VIH
X
High Z
VIL
High Z
Chip Erase
Notes:
VIL
VH
(3)
1. X can be VIL or VIH.
2. Refer to AC programming waveforms.
3. VH = 12.0V ± 0.5V.
8. DC Characteristics
Symbol
Parameter
Condition
ILI
Input Load Current
ILO
Max
Units
VIN = 0V to VCC + 1V
10
µA
Output Leakage Current
VI/O = 0V to VCC
10
µA
ISB
VCC Standby Current CMOS
CE = VCC - 0.3V to VCC + 1V
50
µA
ICC
VCC Active Current
f = 5 MHz; IOUT = 0 mA
15
mA
VIL
Input Low Voltage
0.6
V
VIH
Input High Voltage
VOL
Output Low Voltage
IOL = 1.6 mA
VOH
Output High Voltage
IOH = -100 µA
6
Min
2.0
V
0.3
2.0
V
V
AT28BV256
0273K–PEEPR–2/09
AT28BV256
9. AC Read Characteristics
AT28BV256-20
Symbol
Parameter
tACC
Min
Max
Units
Address to Output Delay
200
ns
tCE(1)
CE to Output Delay
200
ns
tOE(2)
OE to Output Delay
0
80
ns
tDF(3)(4)
CE or OE to Output Float
0
55
ns
tOH
Output Hold from OE, CE or Address, whichever occurred first
0
ns
10. AC Read Waveforms(1)(2)(3)(4)
tCE
tOE
tDF
tACC
Notes:
tOH
1. CE may be delayed up to tACC - tCE after the address transition without impact on tACC.
2. OE may be delayed up to tCE - tOE after the falling edge of CE without impact on tCE or by tACC - tOE after an address change
without impact on tACC.
3. tDF is specified from OE or CE whichever occurs first (CL = 5 pF).
4. This parameter is characterized and is not 100% tested.
7
0273K–PEEPR–2/09
11. Input Test Waveforms and Measurement Level
tR, tF < 20 ns
12. Output Test Load
13. Pin Capacitance
f = 1 MHz, T = 25°C(1)
Symbol
Typ
Max
Units
Conditions
CIN
4
6
pF
VIN = 0V
COUT
8
12
pF
VOUT = 0V
Note:
8
1. This parameter is characterized and is not 100% tested.
AT28BV256
0273K–PEEPR–2/09
AT28BV256
14. AC Write Characteristics
Symbol
Parameter
tAS, tOES
Address, OE Set-up Time
0
ns
tAH
Address Hold Time
50
ns
tCS
Chip Select Set-up Time
0
ns
tCH
Chip Select Hold Time
0
ns
tWP
Write Pulse Width (WE or CE)
200
ns
tDS
Data Set-up Time
50
ns
tDH, tOEH
Data, OE Hold Time
0
ns
tDV
Note:
Min
Max
Units
(1)
Time to Data Valid
NR
1. NR = No Restriction.
15. AC Write Waveforms
15.1
WE Controlled
tOES
tAS
tOEH
tAH
tCH
tCS
tWPH
tWP
tDV
15.2
tDH
tDS
CE Controlled
tOES
tAS
tOEH
tAH
tCH
tCS
tWPH
tWP
tDV
tDS
tDH
9
0273K–PEEPR–2/09
16. Page Mode Characteristics
Symbol
Parameter
Min
Max
Units
tWC
Write Cycle Time
10
ms
tAS
Address Set-up Time
0
ns
tAH
Address Hold Time
50
ns
tDS
Data Set-up Time
50
ns
tDH
Data Hold Time
0
ns
tWP
Write Pulse Width
200
ns
tBLC
Byte Load Cycle Time
tWPH
Write Pulse Width High
150
100
µs
ns
17. Programming Algorithm(1)(2)(3)
LOAD DATA AA
TO
ADDRESS 5555
LOAD DATA 55
TO
ADDRESS 2AAA
LOAD DATA A0
TO
ADDRESS 5555
WRITES ENABLED(2)
LOAD DATA XX
TO
ANY ADDRESS(3)
LOAD LAST BYTE
TO
LAST ADDRESS(3)
Notes:
ENTER DATA
PROTECT STATE
1. Data Format: I/O7 - I/O0 (Hex); Address Format: A14 - A0 (Hex).
2. Data protect state will be re-activated at the end of program cycle.
3. 1 to 64 bytes of data are loaded.
18. Software Protected Program Cycle Waveforms(1)(2)(3)
tWP
tAS
tAH
tWPH
tBLC
tDH
tDS
tWC
Notes:
1. A0 - A14 must conform to the addressing sequence for the first three bytes as shown above.
2. A6 through A14 must specify the same page address during each high to low transition of WE (or CE) after the software
code has been entered.
3. OE must be high only when WE and CE are both low.
10
AT28BV256
0273K–PEEPR–2/09
AT28BV256
19. Data Polling Characteristics(1)
Symbol
Parameter
tDH
Data Hold Time
tOEH
OE Hold Time
Min
Max
OE to Output Delay
tWR
Write Recovery Time
Units
0
ns
0
ns
(2)
tOE
Notes:
Typ
ns
0
ns
1. These parameters are characterized and not 100% tested.
2. See “AC Read Characteristics” on page 7.
20. Data Polling Waveforms
tOEH
tDH
tWR
tOE
21. Toggle Bit Characteristics(1)
Symbol
Parameter
Min
tDH
Data Hold Time
10
ns
tOEH
OE Hold Time
10
ns
(2)
tOE
OE to Output Delay
tOEHP
OE High Pulse
tWR
Notes:
Typ
Max
Units
ns
Write Recovery Time
150
ns
0
ns
1. These parameters are characterized and not 100% tested.
2. See “AC Read Characteristics” on page 7.
22. Toggle Bit Waveforms
tOEH
tDH
tOE
tWR
Notes:
1. Toggling either OE or CE or both OE and CE will operate toggle bit.
2. Beginning and ending state of I/O6 will vary.
3. Any address location may be used but the address should not vary.
11
0273K–PEEPR–2/09
23. Normalized ICC Graphs
12
AT28BV256
0273K–PEEPR–2/09
AT28BV256
24. Ordering Information
24.1
Green Package Option (Pb/Halide-free)
tACC
(ns)
200
ICC (mA)
Active
15
Standby
0.02
Ordering Code
Package
AT28BV256-20JU
32J
AT28BV256-20SU
28S
AT28BV256-20TU
28T
Operation Range
Industrial
(-40° to 85°C)
Package Type
32J
32-lead, Plastic J-leaded Chip Carrier (PLCC)
28S
28-lead, 0.300" Wide, Plastic Gull Wing Small Outline (SOIC)
28T
28-lead, Plastic Thin Small Outline Package (TSOP)
24.2
Die Products
Contact Atmel Sales for die sales options.
13
0273K–PEEPR–2/09
25. Packaging Information
25.1
32J – PLCC
1.14(0.045) X 45˚
PIN NO. 1
IDENTIFIER
1.14(0.045) X 45˚
0.318(0.0125)
0.191(0.0075)
E1
E
E2
B1
B
e
A2
D1
A1
D
A
0.51(0.020)MAX
45˚ MAX (3X)
COMMON DIMENSIONS
(Unit of Measure = mm)
D2
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"(0.254 mm) 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" (0.102 mm) maximum.
SYMBOL
MIN
NOM
MAX
A
3.175
–
3.556
A1
1.524
–
2.413
A2
0.381
–
–
D
12.319
–
12.573
D1
11.354
–
11.506
D2
9.906
–
10.922
E
14.859
–
15.113
E1
13.894
–
14.046
E2
12.471
–
13.487
B
0.660
–
0.813
B1
0.330
–
0.533
e
NOTE
Note 2
Note 2
1.270 TYP
10/04/01
R
14
2325 Orchard Parkway
San Jose, CA 95131
TITLE
32J, 32-lead, Plastic J-leaded Chip Carrier (PLCC)
DRAWING NO.
REV.
32J
B
AT28BV256
0273K–PEEPR–2/09
AT28BV256
25.2
28S – SOIC
Dimensions in Millimeters and (Inches).
Controlling dimension: Millimeters.
0.51(0.020)
0.33(0.013)
7.60(0.2992) 10.65(0.419)
7.40(0.2914) 10.00(0.394)
PIN 1
1.27(0.50) BSC
TOP VIEW
18.10(0.7125)
17.70(0.6969)
2.65(0.1043)
2.35(0.0926)
0.30(0.0118)
0.10(0.0040)
SIDE VIEWS
0.32(0.0125)
0.23(0.0091)
0º ~ 8º
1.27(0.050)
0.40(0.016)
8/4/03
R
2325 Orchard Parkway
San Jose, CA 95131
TITLE
28S, 28-lead, 0.300" Body, Plastic Gull Wing Small Outline (SOIC)
JEDEC Standard MS-013
DRAWING NO.
REV.
28S
B
15
0273K–PEEPR–2/09
25.3
28T – TSOP
PIN 1
0º ~ 5º
c
Pin 1 Identifier Area
D1 D
L
b
e
L1
A2
E
A
GAGE PLANE
SEATING PLANE
COMMON DIMENSIONS
(Unit of Measure = mm)
A1
MIN
NOM
MAX
A
–
–
1.20
A1
0.05
–
0.15
A2
0.90
1.00
1.05
D
13.20
13.40
13.60
D1
11.70
11.80
11.90
Note 2
E
7.90
8.00
8.10
Note 2
L
0.50
0.60
0.70
SYMBOL
Notes:
1. This package conforms to JEDEC reference MO-183.
2. Dimensions D1 and E do not include mold protrusion. Allowable
protrusion on E is 0.15 mm per side and on D1 is 0.25 mm per side.
3. Lead coplanarity is 0.10 mm maximum.
L1
NOTE
0.25 BASIC
b
0.17
0.22
0.27
c
0.10
–
0.21
e
0.55 BASIC
12/06/02
R
16
2325 Orchard Parkway
San Jose, CA 95131
TITLE
28T, 28-lead (8 x 13.4 mm) Plastic Thin Small Outline
Package, Type I (TSOP)
DRAWING NO.
REV.
28T
C
AT28BV256
0273K–PEEPR–2/09
Headquarters
International
Atmel Corporation
2325 Orchard Parkway
San Jose, CA 95131
USA
Tel: 1(408) 441-0311
Fax: 1(408) 487-2600
Atmel Asia
Unit 1-5 & 16, 19/F
BEA Tower, Millennium City 5
418 Kwun Tong Road
Kwun Tong, Kowloon
Hong Kong
Tel: (852) 2245-6100
Fax: (852) 2722-1369
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Le Krebs
8, Rue Jean-Pierre Timbaud
BP 309
78054 Saint-Quentin-enYvelines Cedex
France
Tel: (33) 1-30-60-70-00
Fax: (33) 1-30-60-71-11
Atmel Japan
9F, Tonetsu Shinkawa Bldg.
1-24-8 Shinkawa
Chuo-ku, Tokyo 104-0033
Japan
Tel: (81) 3-3523-3551
Fax: (81) 3-3523-7581
Technical Support
p_eeprom@atmel.com
Sales Contact
www.atmel.com/contacts
Product Contact
Web Site
www.atmel.com
Literature Requests
www.atmel.com/literature
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0273K–PEEPR–2/09
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