– Internal Address and Data Latches for 64 Bytes
– Internal Control Timer
• Fast Write Cycle Times
– Page Write Cycle Time: 3 ms or 10 ms Maximum
– 1 to 64-byte Page Write Operation
• Low Power Dissipation
– 80 mA Active Current
– 3 mA Standby Current
• Hardware and Software Data Protection
• DATA Polling for End of Write Detection
• High Reliability CMOS Technology
– Endurance: 104 or 105 Cycles
– Data Retention: 10 Years
• Single 5V ± 10% Supply
• CMOS and TTL Compatible Inputs and Outputs
• JEDEC Approved Byte-wide Pinout
• Full Military, Commercial, and Industrial Temperature Ranges
256 (32K x 8)
High-speed
Parallel
EEPROM
Description
The AT28HC256 is a high-performance electrically erasable and programmable read
only memory. Its 256K of memory is organized as 32,768 words by 8 bits. Manufactured with Atmel’s advanced nonvolatile CMOS technology, the AT28HC256 offers
(continued)
Pin Configurations
Pin NameFunction
A0 - A14Addresses
CE
OE
WE
I/O0 - I/O7Data Inputs/Outputs
NCNo Connect
DCDon’t Connect
Note: PLCC package pins 1 and
17 are DON’T CONNECT.
Chip Enable
Output Enable
Write Enable
LCC, PLCC
Top View
1
OE
2
A11
3
A9
4
A8
5
A13
6
WE
7
VCC
8
A14
9
A12
10
A7
11
A6
12
A5
13
A4
14
A3
CERDIP, PDIP, FLATPACK
Top V iew
A14
A12
I/O0
I/O1
I/O2
GND
1
2
3
A7
4
A6
5
A5
6
A4
7
A3
8
A2
9
A1
10
A0
11
12
13
14
28
VCC
27
WE
26
A13
25
A8
24
A9
23
A11
22
OE
21
A10
20
CE
19
I/O7
18
I/O6
17
I/O5
16
I/O4
15
I/O3
TSOP
Top V iew
PGA
To p V i e w
28
A10
27
CE
26
I/O7
25
I/O6
24
I/O5
23
I/O4
22
I/O3
21
GND
20
I/O2
19
I/O1
18
I/O0
17
A0
16
A1
15
A2
AT28HC256
Rev. 0007I–12/99
1
access times to 70 ns with power dissipation of just
440 mW. When the AT28HC256 is deselected, the standby
current is less than 5 mA.
The AT28HC256 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
address and 1 to 64 bytes of data are internally latched,
freeing the addresses 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
Block Diagram
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 28HC256 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.
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 V
Voltage on OE
with Respect to Ground...................................-0.6V to +13.5V
and A9
+ 0.6V
CC
*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
2
AT28HC256
AT28HC256
Device Operation
READ: The AT28HC256 is accessed like a Static RAM.
When CE
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
line control gives designers flexibility in preventing bus contention in their system.
BYTE WRITE: A low pulse on the WE
or WE low (respectively) and OE high initiates a write cycle.
The address is latched on the falling edge of CE
whichever occurs last. The data is latched by the first rising
edge of CE
will automatically time itself to completion. Once a programming operation has been initiated and for the duration
of t
operation.
PAGE WRITE: The page write operation of the
AT28HC256 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
exceeded the AT28C256 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. That is,
for each WE
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.
DATA
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/O
data is valid on all outputs, and the next write cycle may
begin. DATA
cycle.
TOGGLE BIT: In addition to DATA
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/O
between one and zero. Once the write has completed, I/O
will stop toggling and valid data will be read. Testing the
toggle bit may begin at any time during the write cycle.
DATA PROTECTION: If precautions are not taken, inadvertent writes to any 5-volt-only nonvolatile memory may
and OE are low and WE is high, the data stored
or OE is high. This dual-
or CE input with CE
or WE,
or WE. Once a byte write has been started it
, a read operation will effectively be a polling
WC
µs (t
) of the previous byte. If the t
BLC
BLC
limit is
high to low transition during the page write
POLLING: The AT28HC256 features DATA Polling
. Once the write cycle has been completed, true
7
Polling may begin at anytime during the write
Polling the AT28HC256
toggling
6
occur during transition of the host system power supply.
Atmel has incorporated both hardware and software features that will protect the memory against inadvertent
writes.
HARDWARE PROTECTION: Hardware features protect
against inadvertent writes to the AT28HC256 in the following ways: (a) V
write function is inhibited; (b) V
has reached 3.8V the device will automatically time out
V
CC
sense – if VCC is below 3.8V (typical) the
CC
power-on delay – once
CC
5 ms typical) before allowing a write; (c) write inhibit – holding any one of OE
low, CE high or WE high inhibits write
cycles; and (d) noise filter – pulses of less than 15 ns (typical) on the WE
or CE inputs will not initiate a write cycle.
SOFTWARE DATA PROTECTION: A software controlled
data protection feature has been implemented on the
AT28HC256. When enabled, the software data protection
(SDP), will prevent inadvertent writes. The SDP feature
may be enabled or disabled by the user; the AT28HC256 is
shipped from Atmel with SDP disabled.
SDP is enabled by the host system issuing a series of three
write commands; three specific bytes of data are written to
three specific addresses (refer to “Software Data Protection” algorithm). After writing the 3-byte command
sequence and after t
the entire AT28HC256 will be pro-
WC
tected against inadvertent write operations. It should be
noted, that once protected the host may still perform a byte
or page write to the AT28HC256. This is done by preceding
the data to be written by the same 3-byte command
sequence.
Once set, SDP will remain active unless the disable command sequence is issued. Power transitions do not disable
SDP and SDP will protect the AT28HC256 during power-up
and power-down conditions. All command sequences must
conform to the page write timing specifications. It should
also be noted that the data in the enable and disable command sequences is not written to the device and the memory addresses used in the sequence may be written with
data in either a byte or page write operation.
After setting SDP, any attempt to write to the device without
the three byte command sequence will start the internal
write timers. No data will be written to the device; however,
for the duration of t
, read operations will effectively be
WC
polling operations.
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.
6
OPTIONAL CHIP ERASE MODE: The entire device can
be erased using a 6-byte software code. Please see “Soft-
ware Chip Erase” application note for details.
3
DC and AC Operating Range
AT28HC256-70AT28HC256-90AT28HC256-12
Com.0°C - 70°C0°C - 70°C0°C - 70°C
Operating
Temperature (Case)
Ind.-40°C - 85°C-40°C - 85°C-40°C - 85°C
Mil.-55°C - 125°C-55°C - 125°C
V
Power Supply5V ± 10%5V ± 10%5V ± 10%
CC
Operating Modes
ModeCEOEWEI/O
ReadV
(2)
Write
Standby/Write InhibitV
IL
V
IL
IH
Write InhibitXXV
Write InhibitXV
Output DisableXV
Chip EraseV
IL
V
IL
V
IH
(1)
X
IL
IH
(3)
V
H
V
IH
V
IL
D
OUT
D
IN
XHigh Z
IH
X
XHigh Z
V
IL
High Z
Notes: 1. X can be VIL or VIH.
2. Refer to AC programming waveforms.
= 12.0V ± 0.5V.
3. V
H
DC Characteristics
SymbolParameterConditionMinMaxUnits
I
I
I
I
I
V
V
V
V
LI
LO
SB1
SB2
CC
IL
IH
OL
OH
Input Load CurrentVIN = 0V to VCC + 1V10µA
Output Leakage CurrentV
= 0V to V
I/O
CC
10µA
AT28HC256-90, -123mA
VCC Standby Current TTLCE = 2.0V to V
VCC Standby Current CMOSCE = VCC - 0.3V to V
V
Active Currentf = 5 MHz; I
CC
CC
= 0 mA80mA
OUT
AT28HC256-7060mA
AT28HC256-90, -12300µA
CC
Input Low Voltage0.8V
Input High Voltage2.0V
Output Low VoltageIOL = 6.0 mA0.45V
Output High VoltageI
= -4 mA2.4V
OH
4
AT28HC256
AC Read Characteristics
tR, tF < 5 ns
SymbolParameter
AT28HC256
AT28HC256-70AT28C256-90AT28HC256-12
UnitsMinMaxMinMaxMinMax
t
ACC
(1)
t
CE
(2)
t
OE
(3)(4)
t
DF
t
OH
AC Read Waveforms
Address to Output Delay7090120ns
CE to Output Delay7090120ns
OE to Output Delay035040050ns
CE or OE to Output Float035040050ns
Output Hold from OE, CE or Address,
whichever occurred first
(1)(2)(3)(4)
Notes: 1. CE may be delayed up to t
2. OE may be delayed up to tCE - tOE after the falling edge of CE without impact on tCE or by t
without impact on t
is specified from OE or CE whichever occurs first (CL = 5 pF).
3. t
DF
ACC
.
4. This parameter is characterized and is not 100% tested.
000ns
- tCE after the address transition without impact on t
ACC
ACC
.
- tOE after an address change
ACC
Input Test Waveforms and
Output Test Load
Measurement Level
Pin Capacitance
f = 1 MHz, T = 25°C
SymbolTypMaxUnitsConditions
C
IN
C
OUT
Note:1. This parameter is characterized and is not 100% tested.
(1)
46pFV
812pFV
IN
OUT
= 0V
= 0V
5
AC Write Characteristics
SymbolParameterMinMaxUnits
t
AS
t
AH
t
CS
t
CH
t
WP
t
DS
tDH, t
t
DV
, t
OES
OEH
Address, OE Setup Time0ns
Address Hold Time50ns
Chip Select Setup Time0ns
Chip Select Hold Time0ns
Write Pulse Width (WE or CE)100ns
Data Setup Time50ns
Data, OE Hold Time0ns
Time to Data ValidNR
(1)
Note:1. NR = No Restriction.
AC Write Waveforms
WE Controlled
CE Controlled
6
AT28HC256
AT28HC256
Page Mode Write Characteristics
SymbolParameterMinTypMaxUnits
t
WC
Write Cycle Time (option available)
AT28HC256510ms
AT28HC256F23ms
t
AS
t
AH
t
DS
t
DH
t
WP
t
BLC
t
WPH
Address Setup Time0ns
Address Hold Time50ns
Data Setup Time50ns
Data Hold Time0ns
Write Pulse Width 100ns
Byte Load Cycle Time150µs
Write Pulse Width High50ns
Page Mode Write Waveforms
(1)(2)
Notes: 1. A6 through A14 must specify the same page address during each high to low transition of WE (or CE).
2.OE must be high only when WE and CE are both low.
Previous data sheets included the low power suffixes L, LE and LF on the At28HC256 for 120 ns and 90 ns speeds.
The low power parameters are now standard; therefore, the L, LE and LF suffixes are no longer required.
Valid Part Numbers
The following table lists standard Atmel products that can be ordered:
Device NumbersSpeedPackage and Temperature Combinations
AT28HC25670JC, JI, PC, PI
AT28HC25690JC, JI, PC, PI, TC, TI, DM/883, FM/883, UM/883
AT28HC256E90JC, JI, PC, PI, TC, TI, DM/883, FM/883, UM/883
AT28HC256F90JC, JI, PC, PI, TC, TI, DM/883, FM/883, UM/883
AT28HC25612JC, JI, PC, PI, TC, TI, DM/883, FM/883, UM/883
AT28HC256E12JC, JI, PC, PI, TC, TI, DM/883, FM/883, UM/883
AT28HC256F12JC, JI, PC, PI, TC, TI, DM/883, FM/883, UM/883
Die Products
Reference Section: Parallel EEPROM Die Products
13
Packaging Information
28D6, 28-lead, 0.600" Wide, Non-windowed,
Ceramic Dual Inline Package (Cerdip)
Dimensions in Inches and (Millimeters)
MIL-STD-1835 D-10 CONFIG A
1.49(37.9)
.225(5.72)
SEATING
PLANE
MAX
.200(5.08)
.125(3.18)
.110(2.79)
.090(2.29)
.015(.381)
.008(.203)
1.44(36.6)
1.300(33.02) REF
.065(1.65)
.045(1.14)
.620(15.7)
.590(15.0)
PIN
1
.610(15.5)
.510(13.0)
.023(.584)
.014(.356)
0
REF
15
.700(17.8) MAX
.098(2.49)
.005(.127)
.060(1.52)
.015(.381)
MAX
MIN
28F, 28-lead, Non-windowed, Ceramic Bottombrazed Flat Package (Flatpack)
Dimensions in Inches and (Millimeters)
MIL-STD-1835 F-12 CONFIG B
PIN #1 ID
.728(18.5)
.712(18.1)
.416(10.6)
.384(9.75)
.006(.152)
.004(.102)
.077(1.96)
.043(1.09)
.286(7.26)
.274(6.96)
.370(9.40)
.250(6.35)
.019(.483)
.015(.381)
.050(1.27) BSC
.045(1.14) MAX
.119(3.02)
.087(2.21)
.045(1.14)
.026(.660)
32J, 32-lead, Plastic J-leaded Chip Carrier (PLCC)
Dimensions in Inches and (Millimeters)
JEDEC STANDARD MS-016 AE
.045(1.14) X 45˚
.032(.813)
.026(.660)
.050(1.27) TYP
.453(11.5)
.447(11.4)
.495(12.6)
.485(12.3)
PIN NO. 1
IDENTIFY
.300(7.62) REF
.430(10.9)
.390(9.90)
.025(.635) X 30˚ - 45˚
.553(14.0)
.547(13.9)
.595(15.1)
.585(14.9)
AT CONTACT
POINTS
.022(.559) X 45˚ MAX (3X)
.012(.305)
.008(.203)
.530(13.5)
.490(12.4)
.021(.533)
.013(.330)
.030(.762)
.015(.381)
.095(2.41)
.060(1.52)
.140(3.56)
.120(3.05)
32L, 32-pad, Non-windowed, Ceramic Leadless Chip
Carrier (LCC)
Dimensions in Inches and (Millimeters)*
MIL-STD-1835 C-12
*Controlling dimension: millimeters
14
AT28HC256
Packaging Information
AT28HC256
28P6, 28-lead, 0.600" Wide, Plastic Dual Inline
Package (PDIP)
Dimensions in Inches and (Millimeters)
JEDEC STANDARD MS-011 AB
1.47(37.3)
.220(5.59)
SEATING
PLANE
MAX
.161(4.09)
.125(3.18)
.110(2.79)
.090(2.29)
.012(.305)
.008(.203)
1.44(36.6)
1.300(33.02) REF
.065(1.65)
.041(1.04)
.630(16.0)
.590(15.0)
.690(17.5)
.610(15.5)
PIN
1
.566(14.4)
.530(13.5)
.090(2.29)
.005(.127)
.065(1.65)
.015(.381)
.022(.559)
.014(.356)
0
REF
15
28S, 28-lead, 0.300" Wide, Plastic Gull Wing Small
Outline (SOIC)
Dimensions in Inches and (Millimeters)
MAX
MIN
28T, 28-lead, Plastic Thin Small Outline Package
(TSOP)
Dimensions in Millimeters and (Inches)*
INDEX
MARK
AREA
0.55 (0.022)
BSC
0
REF
5
7.15 (0.281)
REF
8.10 (0.319)
7.90 (0.311)
0.20 (0.008)
0.10 (0.004)
0.70 (0.028)
0.30 (0.012)
11.9 (0.469)
11.7 (0.461)
0.27 (0.011)
0.18 (0.007)
13.7 (0.539)
13.1 (0.516)
1.25 (0.049)
1.05 (0.041)
0.20 (0.008)
0.15 (0.006)
*Controlling dimension: millimeters
28U, 28-pin, Ceramic Pin Grid Array (PGA)
Dimensions in Inches and (Millimeters)
15
Atmel HeadquartersAtmel Operations
Corporate Headquarters
2325 Orchard Parkway
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TEL (408) 441-0311
FAX (408) 487-2600
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Atmel U.K., Ltd.
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England
TEL (44) 1276-686-677
FAX (44) 1276-686-697
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TEL (852) 2721-9778
FAX (852) 2722-1369
Japan
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9F, Tonetsu Shinkawa Bldg.
1-24-8 Shinkawa
Chuo-ku, Tokyo 104-0033
Japan
TEL (81) 3-3523-3551
FAX (81) 3-3523-7581
Atmel Colorado Springs
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Colorado Springs, CO 80906
TEL (719) 576-3300
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Atmel Rousset
Zone Industrielle
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France
TEL (33) 4-4253-6000
FAX (33) 4-4253-6001
Atmel Corporation makes no warranty for the use of its products, other than those expressly contained in the Company’s standard warranty which is detailed in Atmel’s Terms and Conditions located on the Company’s web site. The Company assumes no responsibility for
any errors which may appear in this document, reserves the right to change devices or specifications detailed herein at any time without
notice, and does not make any commitment to update the information contained herein. No licenses to patents or other intellectual property of Atmel are granted by the Company in connection with the sale of Atmel products, expressly or by implication. Atmel’s products are
not authorized for use as critical components in life support devices or systems.
®
Marks bearing
Terms and product names in this document may be trademarks of others.
and/or ™ are registered trademarks and trademarks of Atmel Corporation.
Printed on recycled paper.
0007I–12/99/xM
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