AMD AM28F256-90FIB 256 kilobit (32 k x 8-bit) cmos 12.0 volt, bulk erase flash memory Datasheet

FINAL
Am28F256
256 Kilobit (32 K x 8-Bit)
CMOS 12.0 Volt, Bulk Erase Flash Memory
DISTINCTIVE CHARACTERISTICS
■ High performance
— 70 ns maximum access time
■ CMOS Low power consumption
— 30 mA maximum active current
— 100 µA maximum standby current
— No data retention power consumption
■ Compatible with JEDEC-standard byte-wide
32-Pin EPROM pinouts
— 32-pin PDIP
— 32-pin PLCC
— 32-pin TSOP
■ 10,000 write/erase cycles minimum
■ Write and erase voltage 12.0 V ±5%
■ Latch-up protected to 100 mA
from –1 V to V CC +1 V
■ Flasherase Electrical Bulk Chip-Erase
— One second typical chip-erase
■ Flashrite Programming
— 10 µs typical byte-program
— 0.5 second typical chip program
■ Command register architecture for
microprocessor/microcontroller compatible
write interface
■ On-chip address and data latches
■ Advanced CMOS flash memory technology
— Low cost single transistor memory cell
■ Automatic write/erase pulse stop timer
GENERAL DESCRIPTION
The Am28F256 is a 256 K Flash memory organized as
32 Kbytes of 8 bits each. AMD’s Flash memories offer
the most cost-effective and reliable read/write nonvolatile random access memory. The Am28F256 is
packaged in 32-pin PDIP, PLCC, and TSOP versions. It
is designed to be reprogrammed and erased in-system
or in standard EPROM programmers. The Am28F256
is erased when shipped from the factory.
The standard Am28F256 offers access times as fast as
70 ns, allowing operation of high-speed microprocessors without wait states. To eliminate bus contention,
the Am28F256 has separate chip enable (CE #) and
output enable (OE #) controls.
AMD’s Flash memories augment EPROM functionality
with in-circuit electrical erasure and programming. The
Am28F256 uses a command register to manage this
functionality, while maintaining a standard JEDEC
Flash Standard 32-pin pinout. The command register
allows for 100% TTL level control inputs and fixed
power supply levels during erase and programming.
AMD’s Flash technology reliably stores memor y
contents even after 10,000 erase and program cycles.
Publication# 11560 Rev: G Amendment/+2
Issue Date: January 1998
The AMD cell is designed to optimize the erase and
programming mechanisms. In addition, the combination of advanced tunnel oxide processing and low
internal electric fields for erase and programming
operations produces reliable cycling. The Am28F256
uses a 12.0V ± 5% VPP high voltage input to perform
the Flasherase and Flashrite algorithms.
The highest degree of latch-up protection is achieved
with AMD’s proprietar y non-epi process. Latch-up
protection is provided for stresses up to 100 milliamps
on address and data pins from –1 V to V CC +1 V.
The Am28F256 is byte programmable using 10 µs
programming pulses in accordance with AMD’s
Flashrite programming algorithm. The typical room
temperature programming time of the Am28F256 is a
half a second. The entire chip is bulk erased using
10 ms erase pulses according to AMD’s Flasherase
alrogithm. Typical erasure at room temperature is
accomplished in less than one second. The windowed
package and the 15-20 minutes required for EPROM
erasure using ultra-violet light are eliminated.
Commands are written to the command register using
standard microprocessor write timings. Register contents serve as inputs to an internal state-machine which
controls the erase and programming circuitry. During
write cycles, the command register internally latches address and data needed for the programming and erase
operations. For system design simplification, the
Am28F256 is designed to support either WE# or CE#
controlled writes. During a system write cycle, addresses are latched on the falling edge of WE # or CE#
whichever occurs last. Data is latched on the rising edge
of WE# or CE# whichever occurs first. To simplify the fol-
lowing discussion, the WE # pin is used as the write cycle
control pin throughout the rest of this text. All setup and
hold times are with respect to the WE # signal.
AMD’s Flash technology combines years of EPROM
and EEPROM experience to produce the highest levels
of quality, reliability, and cost effectiveness. The
Am28F256 electrically erases all bits simultaneously
using Fowler-Nordheim tunneling. The bytes are
programmed one byte at a time using the EPROM
programming mechanism of hot electron injection.
BLOCK DIAGRAM
DQ0–DQ7
VCC
VSS
Erase
Voltage
Switch
VPP
To Array
State
Control
WE#
Input/Output
Buffers
Program
Voltage
Switch
Command
Register
Chip Enable
Output Enable
Logic
CE#
Data
Latch
OE#
Low V CC
Detector
Program/Erase
Pulse Timer
A0–A14
Address
Latch
Y-Decoder
Y-Gating
X-Decoder
262,144
Bit
Cell Matrix
11560F-1
PRODUCT SELECTOR GUIDE
Family Part Number
Am28F256
Speed Options (VCC = 5.0 V ± 10%)
-70
-90
-120
-150
-200
Max Access Time (ns)
70
90
120
150
200
CE# (E#) Access (ns)
70
90
120
150
200
OE# (G#) Access (ns)
35
35
50
55
55
2
Am28F256
CONNECTION DIAGRAMS
NC
2
31
WE# (W#)
NC
3
30
NC
WE# (W#)
NC
VCC
VPP
32
NC
1
A12
NC
VPP
VCC
PLCC
PDIP
4 3
2
1 32 31 30
A12
4
29
A14
A7
5
28
A13
A7
5
29
A14
27
A8
A6
6
28
A13
7
8
27
26
A8
A9
A6
6
A5
7
26
A9
A4
8
25
A11
A5
A4
A3
9
24
OE# (G#)
A3
9
25
A11
A2
10
23
A10
A2
10
24
OE# (G#)
A1
11
23
A10
A0
12
22
DQ0
13
21
CE# (E#)
DQ7
A0
12
21
DQ7
DQ0
13
20
DQ6
DQ1
14
19
DQ5
DQ2
15
18
DQ4
VSS
16
17
DQ3
14 15 16 17 18 19 20
DQ5
DQ6
CE# (E#)
DQ4
22
VSS
DQ3
11
DQ1
DQ2
A1
11560F-3
11560F-2
Note: Pin 1 is marked for orientation.
Am28F256
3
CONNECTION DIAGRAMS (continued)
A11
A9
A8
A13
A14
NC
WE#
VCC
VPP
NC
NC
A12
A7
A6
A5
A4
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
32
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
OE#
A10
CE#
D7
D6
D5
D4
D3
VSS
D2
D1
D0
A0
A1
A2
A3
32
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
A11
A9
A8
A13
A14
NC
WE#
VCC
VPP
NC
NC
A12
A7
A6
A5
A4
32-Pin TSOP—Standard Pinout
OE#
A10
CE#
D7
D6
D5
D4
D3
VSS
D2
D1
D0
A0
A1
A2
A3
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
32-Pin TSOP—Reverse Pinout
11560G-4
LOGIC SYMBOL
15
A0–A14
8
DQ0–DQ7
CE# (E#)
OE# (G#)
WE# (W#)
11560F-5
4
Am28F256
ORDERING INFORMATION
Standard Products
AMD standard products are available in several packages and operating ranges. The order number (Valid Combination) is formed
by a combination of:
AM28F256
-70
J
C
B
OPTIONAL PROCESSING
Blank = Standard Processing
B
= Burn-In
Contact an AMD representative for more information.
TEMPERATURE RANGE
C = Commercial (0°C to +70°C)
I = Industrial (–40°C to +85°C)
E = Extended (–55°C to +125°C)
PACKAGE TYPE
P = 32-Pin Plastic DIP (PD 032)
J = 32-Pin Rectangular Plastic Leaded Chip
Carrier (PL 032)
E = 32-Pin Thin Small Outline Package (TSOP)
Standard Pinout (TS 032)
F = 32-Pin Thin Small Outline Package (TSOP)
Reverse Pinout (TSR032)
SPEED OPTION
See Product Selector Guide and Valid Combinations
DEVICE NUMBER/DESCRIPTION
Am28F256
256 Kilobit (32 K x 8-Bit) CMOS Flash Memory
Valid Combinations
Valid Combinations
AM28F256-70
AM28F256-90
AM28F256-120
AM28F256-150
PC, PI, PE,
JC, JI, JE,
EC, EI, EE,
FC, FI, FE
Valid Combinations list configurations planned to be supported in volume for this device. Consult the local AMD sales
office to confirm availability of specific valid combinations and
to check on newly released combinations.
AM28F256-200
Am28F256
5
PIN DESCRIPTION
A0–A14
Address Inputs for memory locations. Internal latches
hold addresses during write cycles.
Power supply for device operation. (5.0 V ± 5% or 10%)
VPP
CE# (E#)
Chip Enable active low input activates the chip’s control
logic and input buffers. Chip Enable high will deselect
the device and operates the chip in stand-by mode.
DQ0–DQ7
Data Inputs during memor y write cycles. Internal
latches hold data during write cycles. Data Outputs
during memory read cycles.
NC
No Connect-corresponding pin is not connected
internally to the die.
OE # (G#)
Output Enable active low input gates the outputs of the
device through the data buffers dur ing memor y
read cycles. Output Enable is high during command
sequencing and program/erase operations.
6
VCC
Program voltage input. VPP must be at high voltage in
order to write to the command register. The command
register controls all functions required to alter the
memory array contents. Memory contents cannot be
altered when VPP ≤ VCC +2 V.
VSS
Ground
WE # (W#)
Write Enable active low input controls the write function
of the command register to the memory array. The
target address is latched on the falling edge of the
Write Enable pulse and the appropriate data is latched
on the rising edge of the pulse. Write Enable high
inhibits writing to the device.
Am28F256
BASIC PRINCIPLES
The device uses 100% TTL-level control inputs to
manage the command register. Erase and reprogramming operations use a fixed 12.0 V ± 5% high
voltage input.
formation must be supplied with the Erase-verify
command. This command verifies the margin and
outputs the addressed byte in order to compare the
a rray da t a w it h F F h d a t a (B yte e ra se d ).
After successful data verification the Erase-verify
command is written again with new address information. Each byte of the array is sequentially verified in this manner.
Read Only Memory
Without high V PP voltage, the device functions as a
read only memor y and operates like a standard
EPROM. The control inputs still manage traditional
read, standby, output disable, and Auto select modes.
Command Register
The command register is enabled only when high voltage is applied to the V PP pin. The erase and reprogramming operations are only accessed via the
register. In addition, two-cycle commands are required
for erase and reprogramming operations. The traditional read, standby, output disable, and Auto select
modes are available via the register.
The device’s command register is written using standard microprocessor write timings. The register controls an internal state machine that manages all device
operations. For system design simplification, the device is designed to support either WE# or CE# controlled writes. During a system write cycle, addresses
are latched on the falling edge of WE# or CE# whichever occurs last. Data is latched on the rising edge of
WE# or CE# whichever occur first. To simplify the following discussion, the WE# pin is used as the write
cycle control pin throughout the rest of this text. All
setup and hold times are with respect to the WE# signal.
Overview of Erase/Program Operations
Flasherase™ Sequence
A multiple step command sequence is required to
erase the Flash device (a two-cycle Erase command
and repeated one cycle verify commands).
Note: The Flash memory array must be completely
programmed to 0’s prior to erasure. Refer to the
Flashrite™ Programming Algorithm.
1. Erase Setup: Write the Setup Erase command to
the command register.
2. Erase: Write the Erase command (same as Setup
Erase command) to the command register again.
The second command initiates the erase operation.
The system software routines must now time-out
the erase pulse width (10 ms) prior to issuing the
Erase-verify command. An integrated stop timer
prevents any possibility of overerasure.
3. Erase-Verify: Write the Erase-verify command to
the command register. This command terminates
the erase operation. After the erase operation,
each byte of the array must be verified. Address in-
If data of the addressed location is not verified, the
Erase sequence is repeated until the entire array is
successfully verified or the sequence is repeated
1000 times.
Flashrite Programming Sequence
A three step command sequence (a two-cycle Program
command and one cycle Verify command) is required
to program a byte of the Flash array. Refer to the Flashrite Algorithm.
1. Program Setup: Write the Setup Program command to the command register.
2. Program: Write the Program command to the command register with the appropriate Address and
Data. The system software routines must now timeout the program pulse width (10 µs) prior to issuing
the Program-verify command. An integrated stop
timer prevents any possibility of overprogramming.
3. Program-Verify: Write the Program-verify command to the command register. This command terminates the programming operation. In addition,
this command verifies the margin and outputs the
byte just programmed in order to compare the array
data with the original data programmed. After successful data verification, the programming sequence is initiated again for the next byte address to
be programmed.
If data is not verified successfully, the Program sequence is repeated until a successful comparison is
verified or the sequence is repeated 25 times.
Data Protection
The device is designed to offer protection against accidental erasure or programming caused by spurious
system level signals that may exist during power transitions. The device powers up in its read only state. Also,
with its control register architecture, alteration of the
memory contents only occurs after successful completion of specific command sequences.
The device also incorporates several features to prevent inadvertent write cycles resulting from VCC powerup and power-down transitions or system noise.
Low VCC Write Inhibit
To avoid initiation of a write cycle during V CC power-up
and power-down, the device locks out write cycles for
Am28F256
7
V CC < V LKO (see DC Characteristics section for
voltages). When VCC < VLKO, the command register is
disabled, all inter nal program/erase circuits are
disabled, and the device resets to the read mode. The
device ignores all writes until V CC > VLKO. The user
must ensure that the control pins are in the correct logic
state when VCC > VLKO to prevent uninitentional writes.
Logical Inhibit
Writing is inhibited by holding any one of OE# = VIL, CE#
= VIH or WE# = VIH. To initiate a write cycle CE# and
WE# must be a logical zero while OE# is a logical one.
Power-Up Write Inhibit
Power-up of the device with WE# = CE# = VIL and
OE# = VIH will not accept commands on the rising
edge of WE#. The internal state machine is automatically reset to the read mode on power-up.
Write Pulse “Glitch” Protection
Noise pulses of less than 10 ns (typical) on OE#, CE#
or WE# will not initiate a write cycle.
FUNCTIONAL DESCRIPTION
Description Of User Modes
Table 1.
Am28F256 Device Bus Operations (Notes 7 and 8)
CE#
(E#)
OE#
(G#)
WE#
(W#)
VPP
(Note 1)
A0
A9
I/O
Read
VIL
VIL
X
VPPL
A0
A9
DOUT
Standby
VIH
X
X
VPPL
X
X
HIGH Z
Output Disable
VIL
VIH
VIH
VPPL
X
X
HIGH Z
Auto-select Manufacturer
Code (Note 2)
VIL
VIL
VIH
VPPL
VIL
VID
(Note 3)
CODE
(01h)
Auto-select Device
Code (Note 2)
VIL
VIL
VIH
VPPL
VIH
VID
(Note 3)
CODE
(A1h)
Read
VIL
VIL
VIH
VPPH
A0
A9
DOUT
(Note 4)
Standby (Note 5)
VIH
X
X
VPPH
X
X
HIGH Z
Output Disable
VIL
VIH
VIH
VPPH
X
X
HIGH Z
Write
VIL
VIH
VIL
VPPH
A0
A9
DIN
(Note 6)
Operation
Read-Only
Read/Write
Legend:
X = Don’t care, where Don’t Care is either V IL or VIH levels. VPPL = V PP < VCC + 2 V. See DC Characteristics for voltage levels
of V PPH. 0 V < An < VCC + 2 V, (normal TTL or CMOS input levels, where n = 0 or 9).
Notes:
1. VPPL may be grounded, connected with a resistor to ground, or < VCC + 2.0 V. VPPH is the programming voltage specified for
the device. Refer to the DC characteristics. When V PP = VPPL, memory contents can be read but not written or erased.
2. Manufacturer and device codes may also be accessed via a command register write sequence. Refer to Table 2.
3. 11.5 < V ID < 13.0 V. Minimum V ID rise time and fall time (between 0 and VID voltages) is 500 ns.
4. Read operation with V PP = VPPH may access array data or the Auto select codes.
5. With VPP at high voltage, the standby current is ICC + IPP (standby).
6. Refer to Table 3 for valid DIN during a write operation.
7. All inputs are Don’t Care unless otherwise stated, where Don’t Care is either VIL or VIH levels. In the Auto select mode all
addresses except A 9 and A0 must be held at VIL .
8. If V CC ≤ 1.0 Volt, the voltage difference between VPP and VCC should not exceed 10.0 volts. Also, the Am28F256 has a V PP
rise time and fall time specification of 500 ns minimum.
8
Am28F256
READ ONLY MODE
When V PP is less than VCC + 2 V, the command register
is inactive. The device can either read array or autoselect data, or be standby mode.
Read
The device functions as a read only memory when V PP
< VCC + 2 V. The device has two control functions. Both
must be satisfied in order to output data. CE# controls
power to the device. This pin should be used for specific device selection. OE# controls the device outputs
and should be used to gate data to the output pins if a
device is selected.
Address access time tACC is equal to the delay from
stable addresses to valid output data. The chip enable
access time tCE is the delay from stable addresses and
stable CE# to valid data at the output pins. The output
enable access time is the delay from the falling edge of
OE# to valid data at the output pins (assuming the addresses have been stable at least t ACC–tOE).
Standby Mode
Output Disable
Output from the device is disabled when OE# is at a
logic high level. When disabled, output pins are in a
high impedance state.
Auto Select
Flash memories can be programmed in-system or in a
standard PROM programmer. The device may be soldered to the circuit board upon receipt of shipment and
programmed in-system. Alternatively, the device may
initially be programmed in a PROM programmer prior
to soldering the device to the board.
The Auto select mode allows the reading out of a binary
code from the device that will identify its manufacturer
and type. This mode is intended for the purpose
of automatically matching the device to be programmed with its corresponding programming algor ith m. Th is mo de is f unc tio nal ove r t he en tir e
temperature range of the device.
Programming In A PROM Programmer
The device has two standby modes. The CMOS
standby mode (CE# input held at VCC ± 0.5 V), consumes less than 100 µA of current. TTL standby mode
(CE# is held at V IH) reduces the current requirements
to less than 1mA. When in the standby mode the outputs are in a high impedance state, independent of the
OE# input.
If the device is deselected during erasure, programming, or program/erase verification, the device will
draw active current until the operation is terminated.
Table 2.
To activate this mode, the programming equipment
must force VID (11.5 V to 13.0 V) on address A9. Two
identifier bytes may then be sequenced from the device
outputs by toggling address A 0 from VIL to VIH. All other
address lines must be held at VIL , and VPP must be
less than or equal to VCC + 2.0 V while using this Auto
select mode. Byte 0 (A0 = VIL ) represents the manufacturer code and byte 1 (A0 = V IH) the device identifier
code. For the device these two bytes are given in Table
2 below. All identifiers for manufacturer and device
codes will exhibit odd parity with the MSB (DQ7) defined as the parity bit.
Am28F256 Auto Select Code
Type
A0
Code
(HEX)
Manufacturer Code
VIL
01
Device Code
VIH
A1
Am28F256
9
ERASE, PROGRAM, AND READ MODE
Refer to AC Write Characteristics and the Erase/Programming Waveforms for specific timing parameters.
When V PP is equal to 12.0 V ± 5%, the command register is active. All functions are available. That is, the
device can program, erase, read array or autoselect
data, or be standby mode.
Command Definitions
The contents of the command register default to 00h
(Read Mode) in the absence of high voltage applied to
the VPP pin. The device operates as a read only memory. High voltage on the VPP pin enables the command
register. Device operations are selected by writing specific data codes into the command register. Table 3 defines these register commands.
Write Operations
High voltage must be applied to the V PP pin in order to
activate the command register. Data written to the register serves as input to the internal state machine. The
output of the state machine determines the operational
function of the device.
The command register does not occupy an addressable
memory location. The register is a latch that stores the
command, along with the address and data information
needed to execute the command. The register is written
by bringing WE# and CE# to VIL, while OE# is at VIH.
Addresses are latched on the falling edge of WE#, while
data is latched on the rising edge of the WE# pulse.
Standard microprocessor write timings are used.
Read Command
Memory contents can be accessed via the read command when V PP is high. To read from the device, write
00h into the command register. Standard microprocessor read cycles access data from the memory. The device will remain in the read mode until the command
register contents are altered.
The command register defaults to 00h (read mode)
upon VPP power-up. The 00h (Read Mode) register default helps ensure that inadvertent alteration of the
memory contents does not occur during the V PP power
transition. Refer to the AC Read Characteristics and
Waveforms for the specific timing parameters.
The device requires the OE# pin to be VIH for write operations. This condition eliminates the possibility for
bus contention during programming operations. In
order to write, OE# must be VIH, and CE# and WE#
must be VIL. If any pin is not in the correct state a write
command will not be executed.
Table 3.
Am28F256 Command Definitions
First Bus Cycle
Address
(Note 2)
Second Bus Cycle
Command (Note 4)
Operation
(Note 1)
Data
(Note 3)
Read Memory
Write
X
00h/FFh
Read Auto select
Write
X
Erase Set-up/Erase Write
Write
Erase-Verify
Operation
(Note 1)
Read
Address
(Note 2)
Data
(Note 3)
RA
RD
80h or 90h Read
00h/01h
01h/A1h
X
20h
Write
X
20h
Write
EA
A0h
Read
X
EVD
Program Setup/Program
Write
X
40h
Write
PA
PD
Program-Verify
Write
X
C0h
Read
X
PVD
Reset
Write
X
FFh
Write
X
FFh
Notes:
1. Bus operations are defined in Table 1.
2. RA = Address of the memory location to be read.
EA = Address of the memory location to be read during erase-verify.
PA = Address of the memory location to be programmed.
X = Don’t care.
Addresses are latched on the falling edge of the WE# pulse.
3. RD = Data read from location RA during read operation.
EVD = Data read from location EA during erase-verify.
PD = Data to be programmed at location PA. Data latched on the rising edge of WE#.
PVD = Data read from location PA during program-verify. PA is latched on the Program command.
4. Refer to the appropriate section for algorithms and timing diagrams.
10
Am28F256
FLASHERASE ERASE SEQUENCE
Erase Setup
Erase Setup is the first of a two-cycle erase command.
It is a command-only operation that stages the device
for bulk chip erase. The array contents are not altered
with this command. 20h is written to the command register in order to perform the Erase Setup operation.
Erase
The second two-cycle erase command initiates the
bulk erase operation. You must write the Erase command (20h) again to the register. The erase operation
begins with the rising edge of the WE# pulse. The
erase operation must be terminated by writing a new
command (Erase-verify) to the register.
This two step sequence of the Setup and Erase commands helps to ensure that memory contents are not
accidentally erased. Also, chip erasure can only occur
when high voltage is applied to the V PP pin and all control pins are in their proper state. In absence of this high
voltage, memory contents cannot be altered. Refer to
AC Erase Characteristics and Waveforms for specific
timing parameters.
Note: The Flash memory device must be fully
programmed to 00h data prior to erasure. This
equalizes the charge on all memory cells ensuring
reliable erasure.
Erase-Verify Command
The erase operation erases all bytes of the array
in parallel. After the erase operation, all bytes must be
sequentially verified. The Erase-verify operation is initi-
ated by writing A0h to the register. The byte address to
be verified must be supplied with the command. Addresses are latched on the falling edge of the WE#
pulse or CE# pulse, whichever occurs later. The rising
edge of the WE# pulse terminates the erase operation.
Margin Verify
During the Erase-verify operation, the device applies
an int er na lly g en erat ed ma rg in vo lta ge to th e
addressed byte. Reading FFh from the addressed byte
indicates that all bits in the byte are properly erased.
Verify Next Address
You must write the Erase-verify command with the appropriate address to the register prior to verification of
each address. Each new address is latched on the falling edge of WE# or CE# pulse, whichever occurs later.
The process continues for each byte in the memory
array until a byte does not return FFh data or all the
bytes in the array are accessed and verified.
If an address is not verified to FFh data, the entire chip
is erased again (refer to Erase Setup/Erase). Erase
verification then resumes at the address that failed to
verify. Erase is complete when all bytes in the array
have been verified. The device is now ready to be programmed. At this point, the verification operation is terminated by writing a valid command (e.g. Program
Setup) to the command register. Figure 1 and Table 4,
the Flasherase electrical erase algorithm, illustrate how
commands and bus operations are combined to perform electrical erasure. Refer to AC Erase Characteristics and Waveforms for specific timing parameters.
Am28F256
11
Start
Yes
Data = 00h
No
Program All Bytes to 00h
Apply V PPH
Address = 00h
PLSCNT = 0
Write Erase Setup Command
Write Erase Command
Time out 10 ms
Write Erase Verify
Time out 6 µs
Read Data from Device
No
No
PLSCNT =
1000
Yes
Apply VPPL
Increment
PLSCNT
Data = FFh
Yes
Last Address
Erase Error
No
Increment Address
Yes
Write Reset Command
Apply VPPL
Erasure Completed
Figure 1.
12
Flasherase Electrical Erase Algorithm
Am28F256
11559G-6
FLASHERASE ELECTRICAL ERASE ALGORITHM
This Flash memory device erases the entire array in
parallel. The erase time depends on V PP, temperature,
and number of erase/program cycles on the device. In
general, reprogramming time increases as the number
of erase/program cycles increases.
The Flasherase electrical erase algorithm employs an
interactive closed loop flow to simultaneously erase all
bits in the array. Erasure begins with a read of the memory contents. The device is erased when shipped from
the factory. Reading FFh data from the device would
immediately be followed by executing the Flashrite programming algorithm with the appropriate data pattern.
Should the device be currently programmed, data other
than FFh will be returned from address locations.
Follow the Flasherase algorithm. Uniform and reliable
erasure is ensured by first programming all bits in the
device to their charged state (Data = 00h). This is
accomplished using the Flashr ite Programming
Table 4.
Bus Operations
algorithm. Erasure then continues with an initial erase
operation. Erase verification (Data = FFh) begins at
address 0000h and continues through the array to the
la s t a d d r e s s, o r u n t i l d a t a o t h e r t h a n F F h i s
encountered. If a byte fails to verify, the device is
er as e d ag a in . W i th ea ch er as e o pe r at io n , a n
increasing number of bytes verify to the erased state.
Typically, devices are erased in less than 100 pulses
(one second). Erase efficiency may be improved by
storing the address of the last byte that fails to verify in
a register. Following the next erase operation,
verification may start at the stored address location. A
total of 1000 erase pulses are allowed per reprogram
cycle, which corresponds to approximately 10 seconds
of cumulative erase time. The entire sequence of erase
and byte verification is performed with high voltage
applied to the VPP pin. Figure 1 illustrates the electrical
erase algorithm.
Flasherase Electrical Erase Algorithm
Command
Comments
Entire memory must = 00h before erasure (Note 3)
Note: Use Flashrite programming algorithm (Figure 3) for
programming.
Wait for VPP Ramp to VPPH (Note 1)
Initialize:
Addresses
PLSCNT (Pulse count)
Standby
Erase Setup
Data = 20h
Erase
Data = 20h
Write
Duration of Erase Operation (tWHWH2)
Standby
Write
Erase-Verify (Note 2)
Address = Byte to Verify
Data = A0h
Stops Erase Operation
Standby
Write Recovery Time before Read = 6 µs
Read
Read byte to verify erasure
Standby
Compare output to FFh
Increment pulse count
Write
Standby
Reset
Data = FFh, reset the register for read operations
Wait for VPP Ramp to VPPL (Note 1)
Notes:
1. See AC and DC Characteristics for values of V PP parameters. The V PP power supply can be hard-wired to the device or
switchable. When VPP is switched, VPPL may be ground, no connect with a resistor tied to ground, or less than VCC + 2.0 V.
2. Erase Verify is performed only after chip erasure. A final read compare may be performed (optional) after the register is written
with the read command.
3. The erase algorithm Must Be Followed to ensure proper and reliable operation of the device.
Am28F256
13
A
Section
B
C
D
E
F
G
Addresses
CE #
OE #
WE #
20h
Data
Data
Out
A0h
20h
VCC
VPP
11559G-7
A
B
C
D
E
Bus Cycle
Write
Write
Time-out
Write
Time-out
Read
Standby
Command
20h
20h
N/A
A0h
N/A
Compare
Data
N/A
Function
Erase
Setup
Erase
Erase
(10 ms)
EraseVerify
Transition
(6 µs)
Erase
Verification
Proceed per
Erase
Algorithm
Figure 2.
F
G
AC Waveforms For Erase Operations
ANALYSIS OF ERASE TIMING WAVEFORM
Note: This analysis does not include the requirement
to program the entire array to 00h data prior to erasure.
Refer to the Flashrite Programming algorithm.
Erase Setup/Erase
This analysis illustrates the use of two-cycle erase
commands (section A and B). The first erase command (20h) is a Setup command and does not affect
the array data (section A). The second erase command (20h) initiates the erase operation (section B)
on the rising edge of this WE# pulse. All bytes of the
memory array are erased in parallel. No address information is required.
The erase pulse occurs in section C.
Time-Out
A software timing routine (10 ms duration) must be initiated on the rising edge of the WE# pulse of section B.
Note: An integrated stop timer prevents any possibility of overerasure by limiting each time-out period of
10 ms.
Erase-Verify
Upon completion of the erase software timing routine,
the microprocessor must write the Erase-verify command (A0h). This command terminates the erase operation on the rising edge of the WE# pulse (section D).
The Erase-verify command also stages the device for
data verification (section F).
After each erase operation each byte must be verified.
The byte address to be verified must be supplied with
14
Am28F256
the Erase-verify command (section D). Addresses are
latched on the falling edge of the WE# pulse.
Another software timing routine (6 µs duration) must be
executed to allow for generation of internal voltages for
margin checking and read operation (section E).
During Erase-verification (section F) each address that
returns FFh data is successfully erased. Each address
of the array is sequentially verified in this manner by repeating sections D thru F until the entire array is verified or an address fails to verify. Should an address
location fail to verify to FFh data, erase the device
again. Repeat sections A thru F. Resume verification
(section D) with the failed address.
Each data change sequence allows the device to use
up to 1,000 erase pulses to completely erase. Typically
100 erase pulses are required.
Note: All address locations must be programmed to
00h prior to erase. This equalizes the charge on all
memory cells and ensures reliable erasure.
FLASHRITE PROGRAMMING SEQUENCE
Program Setup
The device is programmed byte by byte. Bytes may be
programmed sequentially or at random. Program Setup
is the first of a two-cycle program command. It stages
the device for byte programming. The Program Setup
operation is performed by writing 40h to the command
register.
Program
Only after the program Setup operation is completed
will the next WE# pulse initiate the active programming
operation. The appropriate address and data for programming must be available on the second WE# pulse.
Addresses and data are internally latched on the falling
and rising edge of the WE# pulse respectively. The rising edge of WE# also begins the programming operation. You must write the Program-verify command to
terminate the programming operation. This two step
sequence of the Setup and Program commands helps
to ensure that memory contents are not accidentally
written. Also, programming can only occur when high
voltage is applied to the VPP pin and all control pins are
in their proper state. In absence of this high voltage,
memory contents cannot be programmed.
Refer to AC Characteristics and Waveforms for specific
timing parameters.
Program Verify Command
Following each programming operation, the byte just
programmed must be verified.
Write C0h into the command register in order to initiate
the Program-verify operation. The rising edge of this
WE pulse terminates the programming operation. The
Program-verify operation stages the device for verification of the last byte programmed. Addresses were previously latched. No new information is required.
Margin Verify
During the Program-verify operation, the device applies
an internally generated margin voltage to the addressed byte. A normal microprocessor read cycle outputs the data. A successful comparison between the
programmed byte and the true data indicates that the
byte was successfully programmed. The original programmed data should be stored for comparison. Programming then proceeds to the next desired byte
location. Should the byte fail to verify, reprogram (refer
to Program Setup/Program). Figure 3 and Table 5 indicate how instructions are combined with the bus operations to perform byte programming. Refer to AC
Programming Characteristics and Waveforms for specific timing parameters.
Flashrite Programming Algorithm
The device Flashrite Programming algorithm employs
an interactive closed loop flow to program data byte by
byte. Bytes may be programmed sequentially or at random. The Flashrite Programming algorithm uses 10 µs
programming pulses. Each operation is followed by a
byte verification to determine when the addressed byte
has been successfully programmed. The program algorithm allows for up to 25 programming operations per
byte per reprogramming cycle. Most bytes verify after
the first or second pulse. The entire sequence of programming and byte verification is performed with high
voltage applied to the VPP pin. Figure 3 and Table 5 illustrate the programming algorithm.
Am28F256
15
Start
Apply VPPH
PLSCNT = 0
Write Program Setup Command
Write Program Command (A/D)
Time out 10 µs
Write Program Verify Command
Time out 6 µs
Read Data from Device
No
Verify Byte
No
Increment PLSCNT
Yes
Increment Address
No
PLSCNT =
25?
Yes
Last Address
Yes
Write Reset Command
Apply VPPL
Apply VPPL
Programming Completed
Device Failed
11559G-8
Figure 3.
16
Flashrite Programming Algorithm
Am28F256
Table 5.
Bus Operations
Flashrite Programming Algorithm
Command
Comments
Wait for VPP Ramp to VPPH (Note 1)
Initialize Pulse counter
Standby
Program Setup
Data = 40h
Program
Valid Address/Data
Write
Duration of Programming Operation (tWHWH1)
Standby
Write
Program-Verify (Note 2)
Data = C0h Stops Program Operation
Standby
Write Recovery Time before Read = 6 µs
Read
Read Byte to Verify Programming
Standby
Compare Data Output to Data Expected
Write
Standby
Reset
Data = FFh, resets the register for read operations.
Wait for VPP Ramp to VPPL (Note 1)
Notes:
1. See AC and DC Characteristics for values of V PP parameters. The V PP power supply can be hard-wired to the device or
switchable. When VPP is switched, VPPL may be ground, no connect with a resistor tied to ground, or less than VCC + 2.0 V.
2. Program Verify is performed only after byte programming. A final read/compare may be performed (optional) after the register
is written with the read command.
Am28F256
17
B
A
Section
C
D
E
F
G
Addresses
CE #
OE #
WE #
Data
In
20h
Data
Data
Out
A0h
VCC
VPP
11559G-9
A
B
C
D
E
Bus Cycle
Write
Write
Time-out
Write
Time-out
Read
Standby
Command
40h
Program
Address,
Program Data
N/A
C0h
(Stops
Program)
N/A
Compare
Data
N/A
Program
Setup
Program
Command
Latch
Address and
Data
Program
(10 µs)
Program
Verify
Transition
(6 µs)
Program
Verification
Proceed per
Programming
Algorithm
Function
Figure 4.
F
G
AC Waveforms for Programming Operations
ANALYSIS OF PROGRAM TIMING WAVEFORMS
Program Setup/Program
Time-Out
Two-cycle write commands are required for program
operations (section A and B). The first program command (40h) is a Setup command and does not affect
the array data (section A). The second program command latches address and data required for programming on the falling and rising edge of WE# respectively
(section B). The rising edge of this WE# pulse (section
B) also initiates the programming pulse. The device is
programmed on a byte by byte basis either sequentially
or randomly.
A software timing routine (10 µs duration) must be initiated on the rising edge of the WE# pulse of section B.
The program pulse occurs in section C.
18
Note: An integrated stop timer prevents any possibility
of overprogramming by limiting each time-out period of
10 µs.
Program-Verify
Upon completion of the program timing routine, the microprocessor must write the program-verify command
(C0h). This command terminates the programming operation on the rising edge of the WE# pulse (section D).
The program-verify command also stages the device
for data verification (section F). Another software timing
routine (6 µs duration) must be executed to allow for
Am28F256
generation of internal voltages for margin checking and
read operations (section E).
Parallel Device Erasure
During program-verification (section F) each byte just
programmed is read to compare array data with original
program data. When successfully verified, the next desired address is programmed. Should a byte fail to verify, reprogram the byte (repeat section A thru F). Each
data change sequence allows the device to use up to
25 program pulses per byte. Typically, bytes are verified
within one or two pulses.
Many applications will use more than one Flash
memory device. Total erase time may be minimized by
implementing a parallel erase algorithm. Flash
memories may erase at different rates. Therefore each
device must be verified separately. When a device is
completely erased and verified use a masking code to
prevent further erasure. The other devices will continue
to erase until verified. The masking code applied could
be the read command (00h).
Algorithm Timing Delays
Power-Up/Power-Down Sequence
There are four different timing delays associated with
the Flasherase and Flashrite algorithms:
The device powers-up in the Read only mode. Power
supply sequencing is not required. Note that if V CC ≤
1.0 Volt, the voltage difference between V PP and V CC
should not exceed 10.0 Volts. Also, the device has VPP
rise time and fall time specification of 500 ns minimum.
1. The first delay is associated with the VPP rise-time
when VPP first turns on. The capacitors on the VPP
bus cause an RC ramp. After switching on the V PP,
the delay required is proportional to the number of
devices being erased and the 0.1 mF/device. VPP
must reach its final value 100 ns before commands
are executed.
2. The second delay time is the erase time pulse width
(10 ms). A software timing routine should be run by
the local microprocessor to time out the delay. The
erase operation must be terminated at the conclusion of the timing routine or prior to executing any
system interrupts that may occur during the erase
operation. To ensure proper device operation, write
the Erase-verify operation after each pulse.
3. A third delay time is required for each programming
pulse width (10 ms). The programming algorithm is
interactive and verifies each byte after a program
pulse. The program operation must be terminated at
the conclusion of the timing routine or prior to executing any system interrupts that may occur during
the programming operation.
4. A fourth timing delay associated with both the
Flasherase and Flashrite algorithms is the write recovery time (6 ms). During this time internal circuitry
is changing voltage levels from the erase/ program
level to those used for margin verify and read operations. An attempt to read the device during this period will result in possible false data (it may appear
the device is not properly erased or programmed).
Note: Software timing routines should be written in
machine language for each of the delays. Code written
in machine language requires knowledge of the appropriate microprocessor clock speed in order to accurately time each delay.
Reset Command
The Reset command initializes the Flash memory device to the Read mode. In addition, it also provides the
user with a safe method to abort any device operation
(including program or erase).
The Reset command must be written two consecutive
times after the setup Program command (40h). This will
reset the device to the Read mode.
Following any other Flash command write the Reset
command once to the device. This will safely abort any
previous operation and initialize the device to the
Read mode.
The Setup Program command (40h) is the only command that requires a two sequence reset cycle. The
first Reset command is interpreted as program data.
However, FFh data is considered null data during programming operations (memory cells are only programmed from a logical “1” to “0”). The second Reset
command safely aborts the programming operation
and resets the device to the Read mode.
Memory contents are not altered in any case.
This detailed information is for your reference. It may
prove easier to always issue the Reset command two
consecutive times. This eliminates the need to determine if you are in the setup Program state or not.
Programming In-System
Flash memories can be programmed in-system or in a
standard PROM programmer. The device may be soldered to the circuit board upon receipt of shipment and
programmed in-system. Alternatively, the device may
initially be programmed in a PROM programmer prior
to soldering the device to the board.
Am28F256
19
Auto Select Command
AMD’s Flash memories are designed for use in applications where the local CPU alters memory contents. Accordingly, manufacturer and device codes must be
accessible while the device resides in the target system. PROM programmers typically access the signature codes by raising A9 to a high voltage. However,
multiplexing high voltage onto address lines is not a
generally desired system design practice.
20
The device contains an Auto Select operation to supplement traditional PROM programming methodology.
The operation is initiated by writing 80h or 90h into the
command register. Following this command, a read
cycle address 0000h retrieves the manufacturer code
of 01h. A read cycle from address 0001h returns the
device code. To terminate the operation, it is necessary
to write another valid command, such as Reset (FFh),
into the register.
Am28F256
ABSOLUTE MAXIMUM RATINGS
OPERATING RANGES
Storage Temperature . . . . . . . . . . . . –65°C to +150°C
Plastic Packages . . . . . . . . . . . . . . . –65°C to +125°C
Commercial (C) Devices
Ambient Temperature (TA). . . . . . . . . . . .0°C to +70°C
Ambient Temperature
with Power Applied . . . . . . . . . . . . . .–55°C to + 125°C
Industrial (I) Devices
Ambient Temperature (TA). . . . . . . . . .–40°C to +85°C
Voltage with Respect To Ground
All pins except A9 and V PP (Note 1) . –2.0 V to +7.0 V
Extended (E) Devices
Ambient Temperature (TA). . . . . . . . .–55°C to +125°C
VCC (Note 1). . . . . . . . . . . . . . . . . . . . –2.0 V to +7.0 V
VCC Supply Voltages
VCC . . . . . . . . . . . . . . . . . . . . . . . . +4.50 V to +5.50 V
A9 (Note 2). . . . . . . . . . . . . . . . . . . . –2.0 V to +14.0 V
VPP (Note 2). . . . . . . . . . . . . . . . . . . –2.0 V to +14.0 V
Output Short Circuit Current (Note 3) . . . . . . 200 mA
Notes:
1. Minimum DC voltage on input or I/O pins is –0.5 V. During
voltage transitions, inputs may overshoot V SS to –2.0 V for
periods of up to 20 ns. Maximum DC voltage on input and
I/O pins is VCC + 0.5 V. During voltage transitions, input
and I/O pins may overshoot to V CC + 2.0V for periods up
to 20ns.
VPP Voltages
Read . . . . . . . . . . . . . . . . . . . . . . . . –0.5 V to +12.6 V
Program, Erase, and Verify . . . . . . +11.4 V to +12.6 V
Operating ranges define those limits between which the
functionality of the device is guaranteed.
2. Minimum DC input voltage on A9 and V PP pins is –0.5 V.
During voltage transitions, A9 and V PP may overshoot
VSS to –2.0 V for periods of up to 20 ns. Maximum DC
input voltage on A9 and V PP is +13.0 V which may
overshoot to 14.0 V for periods up to 20 ns.
3. No more than one output shorted to ground at a time. Duration of the short circuit should not be greater than one
second.
Stresses above those listed under “Absolute Maximum
Ratings” may cause permanent damage to the device. This is
a stress rating only; functional operation of the device at these
or any other conditions above those indicated in the operational sections of this specification is not implied. Exposure of
the device to absolute maximum rating conditions for extended
periods may affect device reliability.
Am28F256
21
MAXIMUM OVERSHOOT
Maximum Negative Input Overshoot
20 ns
20 ns
+0.8 V
–0.5 V
–2.0 V
20 ns
11560F-10
Maximum Positive Input Overshoot
20 ns
VCC + 2.0 V
VCC + 0.5 V
2.0 V
20 ns
20 ns
11560F-11
Maximum VPP Overshoot
20 ns
14.0 V
13.5 V
VCC + 0.5 V
20 ns
20 ns
11560F-12
22
Am28F256
DC CHARACTERISTICS over operating range unless otherwise specified
TTL/NMOS Compatible
Parameter
Symbol
Parameter Description
Test Conditions
Min
Typ
Max
Unit
ILI
Input Leakage Current
VCC = VCC Max, VIN = VCC or VSS
±1.0
µA
ILO
Output Leakage Current
VCC = VCC Max, VOUT = VCC or V SS
±1.0
µA
ICCS
VCC Standby Current
VCC = VCC Max, CE# = VIH
0.2
1.0
mA
ICC1
VCC Active Read Current
VCC = VCC Max, CE# = VIL, OE# = V IH
IOUT = 0 mA, at 6 MHz
20
30
mA
ICC2
VCC Programming Current
CE# = VIL
Programming in Progress (Note 4)
20
30
mA
ICC3
VCC Erase Current
CE# = VIL
Erasure in Progress (Note 4)
20
30
mA
IPPS
VPP Standby Current
VPP = VPPL
±1.0
µA
IPP1
VPP Read Current
IPP2
VPP Programming Current
VPP = VPPH
Programming in Progress (Note 4)
10
30
mA
IPP3
VPP Erase Current
VPP = VPPH
Erasure in Progress (Note 4)
10
30
mA
VIL
Input Low Voltage
–0.5
0.8
V
VIH
Input High Voltage
2.0
VCC + 0.5
V
VOL
Output Low Voltage
IOL = 5.8 mA, VCC = VCC Min
0.45
V
VOH1
Output High Voltage
IOH = –2.5 mA, VCC = VCC Min
2.4
VID
A9 Auto Select Voltage
A9 = VID
11.5
IID
A9 Auto Select Current
A9 = VID Max, VCC = V CC Max
VPPL
VPP during Read-Only
Operations
Note: Erase/Program are inhibited
when VPP = VPPL
VPPH
VLKO
VPP = VPPH
70
200
±1.0
VPP = VPPL
µA
V
13.0
V
50
µA
0.0
VCC +2.0
V
VPP during Read/Write
Operations
11.4
12.6
V
Low VCC Lock-out Voltage
3.2
5
3.7
V
Notes:
1. Caution: The Am28F256 must not be removed from (or inserted into) a socket when V CC or VPP is applied. If V CC ≤ 1.0 Volt,
the voltage difference between VPP and VCC should not exceed 10.0 Volts. Also, the Am28F256 has a VPP rise time and fall
time specification of 500 ns minimum.
2. ICC1 is tested with OE# = VIH to simulate open outputs.
3. Maximum active power usage is the sum of I CC and IPP..
4. Not 100% tested.
Am28F256
23
DC CHARACTERISTICS
CMOS Compatible
Parameter
Symbol
Parameter Description
Test Conditions
Min
Typ
Max
Unit
ILI
Input Leakage Current
VCC = VCC Max, VIN = VCC or VSS
±1.0
µA
ILO
Output Leakage Current
VCC = VCC Max, VOUT = VCC or VSS
±1.0
µA
ICCS
VCC Standby Current
VCC = VCC Max, CE# = VCC + 0.5 V
15
100
µA
ICC1
VCC Active Read Current
VCC = VCC Max, CE# = VIL, OE# = VIH
IOUT = 0 mA, at 6 MHz
20
30
mA
ICC2
VCC Programming Current
CE# = V IL
Programming in Progress (Note 4)
20
30
mA
ICC3
VCC Erase Current
CE# = V IL
Erasure in Progress (Note 4)
20
30
mA
IPPS
VPP Standby Current
VPP = VPPL
±1.0
µA
IPP1
VPP Read Current
VPP = VPPH
70
200
µA
IPP2
VPP Programming Current
VPP = VPPH
Programming in Progress (Note 4)
10
30
mA
IPP3
VPP Erase Current
VPP = VPPH
Erasure in Progress (Note 4)
10
30
mA
VIL
Input Low Voltage
–0.5
0.8
V
VIH
Input High Voltage
0.7 VCC
VCC + 0.5
V
VOL
Output Low Voltage
0.45
V
VOH1
Output High Voltage
VOH2
IOL = 5.8 mA, VCC = VCC Min
IOH = –2.5 mA, VCC = VCC Min
0.85 VCC
IOH = –100 µA, VCC = VCC Min
V CC –0.4
VID
A9 Auto Select Voltage
A9 = VID
IID
A9 Auto Select Current
A9 = VID Max, VCC = VCC Max
VPPL
VPPL during Read-Only
Operations
Note: Erase/Program are inhibited
when V PP = VPPL
VPPH
VLKO
V
11.5
13.0
V
50
µA
0.0
VCC + 2.0
V
VPP during Read/Write
Operations
11.4
12.6
V
Low VCC Lock-out Voltage
3.2
5
3.7
V
Notes:
1. Caution: The Am28F256 must not be removed from (or inserted into) a socket when VCC or VPP is applied. If V CC ≤ 1.0 volt,
the voltage difference between V PP and VCC should not exceed 10.0 volts. Also, the Am28F256 has a VPP rise time and fall
time specification of 500 ns minimum.
2. ICC1 is tested with OE# = VIH to simulate open outputs.
3. Maximum active power usage is the sum of I CC and IPP.
4. Not 100% tested.
24
Am28F256
25
20
ICC Active
in mA
15
55°C
0°C
25°C
70°C
125°C
10
5
0
0
1
2
3
4
5
6
7
Frequency in MHz
8
9
10
11
12
11560F-13
Figure 5. Am28F256—Average ICC Active vs. Frequency
VCC = 5.5 V, Addressing Pattern = Minmax
Data Pattern = Checkerboard
TEST CONDITIONS
Table 6.
Test Specifications
5.0 V
Test Condition
Output Load
2.7 kΩ
Device
Under
Test
Output Load Capacitance, CL
(including jig capacitance)
CL
-70
Input Pulse Levels
Note: Diodes are IN3064 or equivalent
Unit
1 TTL gate
30
100
≤10
Input Rise and Fall Times
6.2 kΩ
All others
pF
ns
0.0–3.0
0.45–2.4
V
Input timing measurement
reference levels
1.5
0.8, 2.0
V
Output timing measurement
reference levels
1.5
0.8, 2.0
V
11560G-14
Figure 6.
Test Setup
Am28F256
25
SWITCHING TEST WAVEFORMS
3V
2.4 V
2.0 V
2.0 V
Test Points
0.8 V
1.5 V
Test Points
1.5 V
0.8 V
0V
0.45 V
Input
Input
Output
AC Testing (all speed options except -70): Inputs are driven at
2.4 V for a logic “1” and 0.45 V for a logic “0”. Input pulse rise
and fall times are ≤10 ns.
Output
AC Testing for -70 devices: Inputs are driven at 3.0 V for a
logic “1” and 0 V for a logic “0”. Input pulse rise and fall times
are ≤10 ns.
11560G-15
SWITCHING CHARACTERISTICS over operating range unless otherwise specified
AC Characteristics—Read Only Operation
Parameter Symbols
Am28F256 Speed Options
JEDEC
Standard
-70
-90
-120
-150
-200
Unit
tAVAV
tRC
Read Cycle Time (Note 2)
Min
70
90
120
150
200
ns
tELQV
tCE
Chip Enable AccessTime
Max
70
90
120
150
200
ns
tAVQV
tACC
Address Access Time
Max
70
90
120
150
200
ns
tGLQV
tOE
Output Enable Access Time
Max
35
35
50
55
55
ns
tELQX
tLZ
Chip Enable to Output in Low Z
(Note 2)
Min
0
0
0
0
0
ns
tEHQZ
tDF
Chip Disable to Output in High Z
(Note 1)
Max
20
20
30
35
35
ns
tGLQX
tOLZ
Output Enable to Output in Low Z
(Note 2)
Min
0
0
0
0
0
ns
tGHQZ
tDF
Output Disable to Output in High Z
(Note 2)
Max
20
20
30
35
35
ns
tAXQX
tOH
Output Hold from first of Address,
CE#, or OE# Change (Note 2)
Min
0
0
0
0
0
ns
Write Recovery Time before Read
Min
6
6
6
6
6
µs
VCC Setup Time to Valid Read
(Note 2)
Min
50
50
50
50
50
µs
tWHGL
tVCS
Parameter Description
Notes:
1. Guaranteed by design not tested.
2. Not 100% tested.
26
Am28F256
AC Characteristics—Write/Erase/Program Operations
Parameter Symbols
Am28F256 Speed Options
JEDEC
Standard
-70
-90
-120
-150
-200
Unit
tAVAV
tWC
Write Cycle Time (Note 4)
Min
70
90
120
150
200
ns
tAVWL
tAS
Address Set-up Time
Min
0
0
0
0
0
ns
tWLAX
tAH
Address Hold Time
Min
45
45
50
60
75
ns
tDVWH
tDS
Data Setup Time
Min
45
45
50
50
50
ns
tWHDX
tDH
Data Hold Time
Min
10
10
10
10
10
ns
tWHGL
tWR
Write Recovery Time
before Read
Min
6
6
6
6
6
µs
Read Recovery Time
before Write
Min
0
0
0
0
0
µs
tGHWL
Parameter Description
tELWL
tCS
Chip Enable Set-up Time
Min
0
0
0
0
0
ns
tWHEH
tCH
Chip Enable Hold Time
Min
0
0
0
0
0
ns
tWLWH
tWP
Write Pulse Width
Min
45
45
50
60
60
ns
tWHWL
tWPH
Write Pulse
Width HIGH
Min
20
20
20
20
20
ns
tWHWH1
Duration of Programming
Operation (Note 2)
Min
10
10
10
10
10
µs
tWHWH2
Duration of
Erase Operation (Note 2)
Min
9.5
9.5
9.5
9.5
9.5
ms
tVPEL
VPP Setup Time to
Chip Enable LOW (Note 4)
Min
100
100
100
100
100
ns
tVCS
VCC Set-up Time to
Chip Enable LOW (Note 4)
Min
50
50
50
50
50
µs
tVPPR
VPP Rise Time
90% VPPH (Note 4)
Min
500
500
500
500
500
ns
tVPPF
VPP Fall Time
10% VPPL (Note 4)
Min
500
500
500
500
500
ns
tLKO
VCC < VLKO
to Reset (Note 4)
Min
100
100
100
100
100
ns
Notes:
1. Read timing characteristics during read/write operations are the same as during read-only operations. Refer to AC
Characteristics for Read Only operations.
2. Maximum pulse widths not required because the on-chip program/erase stop timer will terminate the pulse widths internally
on the device.
3. Chip-Enable Controlled Writes: Write operations are driven by the valid combination of Chip-Enable and Write-Enable. In
systems where Chip-Enable defines the Write Pulse Width (within a longer Write-Enable timing waveform) all setup, hold and
inactive Write-Enable times should be measured relative to the Chip-Enable waveform.
4. Not 100% tested.
Am28F256
27
KEY TO SWITCHING WAVEFORMS
WAVEFORM
INPUTS
OUTPUTS
Steady
Changing from H to L
Changing from L to H
Don’t Care, Any Change Permitted
Changing, State Unknown
Does Not Apply
Center Line is High Impedance State (High Z)
SWITCHING WAVEFORMS
Device and
Outputs
Power-up, Standby Address Selection Enabled
Data
Valid
Standby, Power-Down
Addresses Stable
Addresses
tAVAV (tRC)
CE# (E#)
tEHQZ
(tDF)
OE# (G#)
tWHGL
tGHQZ
(tDF)
tGLQV (tOE )
WE# (W#)
tELQV (t CE)
tGLQX (t OLZ)
tVCS
High Z
tAXQX (tOH)
tELQX (tLZ)
Output Valid
Data (DQ)
High Z
tAVQV (tACC)
5.0 V
VCC
0V
11560G-16
Figure 7.
28
AC Waveforms for Read Operations
Am28F256
SWITCHING WAVEFORMS
Power-up,
Standby
Setup Erase
Command
Erase
Command
Erasure
Erase-Verify
Command
Erase
Standby,
Verification Power-down
Addresses
tAVAV (tWC)
tAVAV (tRC)
tWLAX (tAH)
tAVWL (tAS)
CE# (E#)
tELWL (tCS)
tEHQZ (tDF)
tWHEH (t CH)
OE# (G#)
tWHWH2
tWHGL
tGHQZ (tDF)
tGHWL (tOES )
tGLQV (tOE)
WE# (W#)
tWLWH (tWP)
tDVWH (tDS)
Data (DQ)
5.0 V
VCC
0V
HIGH Z
tWHWL (tWPH)
tGLQX (tOLZ)
tAXQX (tOH)
tWHDX (t DH)
DATA IN
= 20h
DATA IN
= 20h
DATA IN =
A0h
VALID
DATA
OUT
tELQX (tLZ)
tELQV (t CE)
tVCS
tVPEL
VPPH
VPP
VPPL
11560F-17
Figure 8.
AC Waveforms for Erase Operations
Am28F256
29
SWITCHING WAVEFORMS
Power-up,
Standby
Setup Program
Command
Program
Command
Latch Address
Verify
Programming Command
and Data
Programming Standby,
Verification Power-down
Addresses
tAVAV (tWC)
tAVWL (tAS)
CE# (E#)
tAVAV (tRC)
tWLAX (tAH)
tELWL (tCS)
tGHQZ (tDF)
tWHEH (tCH)
OE# (G#)
tWHWH1
tWHGL
tGHQZ (tDF)
tGHWL (tOES)
tGLQV (tOE)
WE# (W#)
tWLWH (tWP)
tDVWH (tDS )
Data (DQ)
5.0 V
VCC
0V
tGLQX (tOLZ)
t WHWL (t WPH)
tWHDX (tDH)
HIGH Z
DATA IN
= 40h
DATA IN
tAXQX (tOH)
DATA IN
= C0h
VALID
DATA
OUT
tELQX (t LZ)
tELQV (tCE )
tVCS
tVPEL
VPPH
VPP
VPPL
11560F-18
Figure 9.
30
AC Waveforms for Programming Operations
Am28F256
ERASE AND PROGRAMMING PERFORMANCE
Limits
Parameter
Min
Typ
(Note 1)
Max
(Note 2)
Unit
1
10
sec
Excludes 00h programming prior to erasure
0.5
3
sec
Excludes system-level overhead
Chip Erase Time
Chip Programming Time
Write/Erase Cycles
10,000
Comments
Cycles
Notes:
1. 25 °C, 12 V VPP.
2. Maximum time specified is lower than worst case. Worst case is derived from the Flasherase/Flashrite pulse count
(Flasherase = 1000 max and Flashrite = 25 max). Typical worst case for program and erase is significantly less than the actual
device limit.
LATCHUP CHARACTERISTICS
Min
Max
Input Voltage with respect to VSS on all pins except I/O pins (Including A9 and VPP)
–1.0 V
13.5 V
Input Voltage with respect to VSS on all pins I/O pins
–1.0 V
VCC + 1.0 V
–100 mA
+100 mA
Current
Includes all pins except VCC. Test conditions: VCC = 5.0 V, one pin at a time.
PIN CAPACITANCE
Parameter
Symbol
Parameter Description
Test Conditions
Typ
Max
Unit
Input Capacitance
VIN = 0
8
10
pF
COUT
Output Capacitance
VOUT = 0
8
12
pF
CIN2
VPP Input Capacitance
VPP = 0
8
12
pF
CIN
Note: Sampled, not 100% tested. Test conditions TA = 25°C, f = 1.0 MHz.
DATA RETENTION
Parameter
Test Conditions
Min
Unit
150°C
10
Years
125°C
20
Years
Minimum Pattern Data Retention Time
Am28F256
31
PHYSICAL DIMENSIONS
PD032—32-Pin Plastic DIP (measured in inches)
1.640
1.670
.600
.625
17
32
.009
.015
.530
.580
Pin 1 I.D.
.630
.700
16
.045
.065
0°
10°
.005 MIN
.140
.225
16-038-S_AG
PD 032
EC75
5-28-97 lv
SEATING PLANE
.090
.110
.120
.160
.016
.022
.015
.060
PL032—32-Pin Plastic Leaded Chip Carrier (measured in inches)
.447
.453
.485
.495
.009
.015
.585
.595
.042
.056
.125
.140
Pin 1 I.D.
.080
.095
.547
.553
SEATING
PLANE
.400
REF.
.490
.530
.013
.021
.050 REF.
.026
.032
TOP VIEW
32
SIDE VIEW
Am28F256
16-038FPO-5
PL 032
DA79
6-28-94 ae
PHYSICAL DIMENSIONS
TS032—32-Pin Standard Thin Small Outline Package (measured in millimeters)
0.95
1.05
Pin 1 I.D.
1
7.90
8.10
0.50 B
0.05
0.15
18.30
18.50
19.80
20.20
0.08
0.20
0.10
0.21
1.20
MAX
0°
5°
16-038-TSOP-2
TS 032
DA95
3-25-97 lv
0.50
0.70
Am28F256
33
PHYSICAL DIMENSIONS
TSR032—32-Pin Reversed Thin Small Outline Package (measured in millimeters)
0.95
1.05
Pin 1 I.D.
1
7.90
8.10
0.50 BSC
0.05
0.15
18.30
18.50
19.80
20.20
0.08
0.20
0.10
0.21
1.20
MAX
0°
5°
0.50
0.70
34
Am28F256
16-038-TSOP-2
TSR032
DA95
3-25-97 lv
DATA SHEET REVISION SUMMARY FOR
AM28F256
Revision G+2
Revision G
Deleted the paragraph “(Refer to the AUTO SELECT
paragraph in the ERASE, PROGRAM, and READ
MODE section for programming the Flash memory device in-system).”
Deleted -75, -95, and -250 speed options. Matched formatting to other current data sheets.
Programming In A PROM Programmer:
Revision G+1
Figure 3, Flashrite Programming Algorithm: Moved end
of arrow originating from Increment Address box so
that it points to the PLSCNT = 0 box, not the Write Program Verify Command box. This is a correction to the
diagram on page 6-189 of the 1998 Flash Memory
Data Book.
Trademarks
Copyright © 1998 Advanced Micro Devices, Inc. All rights reserved.
ExpressFlash is a trademark of Advanced Micro Devices, Inc.
AMD, the AMD logo, and combinations thereof are registered trademarks of Advanced Micro Devices, Inc.
Product names used in this publication are for identification purposes only and may be trademarks of their respective companies.
Am28F256
35