Command Cycles
1st Cycle 2nd Cycle
Operation A0-A17 DQ0-DQ7 Operation A0-A17 DQ0-DQ7
Read 1 Write X 00h
Electronic
Signature
(2)
2 Write X 80h or 90h
Read 00000h 20h
Read 00001h F4h
Setup Erase/
2
Write X 20h
Erase Write X 20h
Erase Verify 2 Write A0-A17 A0h Read X Data Output
Setup Program/
2
Write X 40h
Program Write A0-A17 Data Input
Program Verify 2 Write X C0h Read X Data Output
Reset 2 Write X FFh Write X FFh
Notes: 1. X = VILor VIH.
2. Refer also to the Electronic Signaturetable.
Table 5. Commands
(1)
Standby Mode. In the Standby Mode the maxi-
mum supply current is reduced. The device is
placed in the Standby Mode by applying a High
level to the Chip Enable (E) input. When in the
StandbyModetheoutputsare ina highimpedance
state, independantof theOutput Enable (G)input.
Output Disable Mode. When the Output Enable
(G) is High the outputs are in a high impedance
state.
ElectronicSignatureMode.Thismodeallowsthe
readout of two binary codesfromthe device which
identify the manufacturer and device type. This
mode is intended for use by programming equipment to automaticallyselect the correct eraseand
programmingalgorithms.The ElectronicSignature
Mode is activewhen a highvoltage (11.5Vto 13V)
isapplied toaddresslineA9withEandG Low.With
A0 Low the output data is the manufacturercode,
when A0 isHigh the output is thedevice code. All
other address lines should be maintained Low
while reading the codes. The electronicsignature
canalso be accessed in Read/Writemodes.
READ/WRITE MODES, 11.4V≤ V
PP
≤12.6V
When V
PP
is High both read and write operations
may be performed. These are defined by thecontents ofan internalcommand register.Commands
may be written to this register to set-up and execute,Erase,EraseVerify,Program,Program Verify
and Reset modes. Each of these modes needs 2
cycles. Each mode starts with a write operationto
set-upthe command,thisis followedby eitherread
or write operations. The device expects the first
cycle to be a write operation and doesnot corrupt
data at any location in the memory.Read modeis
set-upwith one cycle onlyand maybe followedby
any number of read operations to output data.
ElectronicSignatureRead modeis set-upwithone
cycle and followed by a read cycle to output the
manufactureror device codes.
Awriteto thecommandregisterismadebybringing
WLowwhileEisLow.ThefallingedgeofWlatches
Addresses, while the rising edge latches Data,
which are used for those commands that require
address inputs, command input or provide data
output. The supply voltage V
CC
and the program
voltageV
PP
canbe applied in any order. Whenthe
device is powered up or when V
PP
is ≤ 6.5V the
contentsof thecommand register defaultsto 00h,
thus automatically setting-up Read operations. In
addition a specific command may be used to set
the commandregisterto 00h for readingthe memory. The system designer may chose to provide a
constanthigh V
PP
anduse the registercommands
for all operations,or to switch the V
PP
from low to
high only when needing to erase or program the
memory. All command registeraccess is inhibited
whenV
CC
fallsbelowthe Erase/WriteLockoutVolt-
age (V
LKO
) of 2.5V.
If the device is deselected during Erasure, Programming or verifying it will draw active supply
currentsuntil the operationsare terminated.
The device is protected against stress caused by
long erase or programtimes.If theend ofErase or
Programming operations are not terminated by a
Verifycycle within a maximumtime permitted, an
internal stop timer automatically stops the operation.The deviceremainsin aninactivestate, ready
to start a Verifyor ResetMode operation.
4/21
M28F201