MX26C1000B
erase operation. The two-step command prevents
accidental alteration to memory array. Erase operation
startswiththerisingedgeoftheWE pulseandterminates
with the rising edge of the next WE pulse, which in this
case is the erase verify command.
COMMAND MODE
The 1 Mbit MTP EPROMTM is in Command mode when
highvoltageVPPH isappliedtotheVPP pin.Inthisstatethe
available functions are Read, Program, Program Verify,
Erase and Erase Verify. Reset are selected by writing
commandstotheinputregister.Datafromtheregisterare
input to the state machine. The output from the state
machine determines the function of the device. The
command register serves as a latch to store data for
executing commands. It does not occupy address- able
memory location. Standard microprocessor write timing
is used. Table 2 defines the register commands. The
commandregisteriswrittenbybringingWEtoalogic-low
Level(VIL),whileCEislow.Addressesarelatchedonthe
fallingedgeofWE,whiledataislatchedontherisingedge
of the WE pulse.
ERASE VERIFY
Eacheraseoperationisfollowedbyaneraseverify. The
commandA0Hiswrittenintothecommandregister.The
address of the bytes to be verified is supplied with the
command. The address is latched on the falling edge of
the WE pulse. A reading FFH is returned to confirm all
bits in the byte are erased. This sequence of Set Up
Erase- Erase continues for each address until FFH is
returned. This indicates the entire memory array is
erasedandcompletestheoperation.Eraseverifyoperation
starts at address 0000H and ends at the last address.
Maximum erase pulse duration for the 1Mbit MTP
EPROMTM is100mswithamaximum30pulses.Referto
AC Characteristics and Waveforms for specific timing
parameters.
StandbyandOutputdisablefunctionsarethesameasin
Read Mode, controlled by CE and OE. If the device is
deselected during erasure, programming, or erase/
programverification,thedevicedrawsactivecurrentuntil
theoperationsterminate.
READ COMMAND
To read memory content, write 00H into the command
register while high voltage is applied to
VPP pin(VPP =VPPH).Microprocessorreadcycleretrieves
the data . The device remains enable for read until the
data in the command register are altered. The device is
defaultinreadmodewhenpowerup.Thisistoensureno
accidentalalterationofthememoryoccursduringpower
transition. Refer to AC Read Characteristics and
Waveforms for specific timing parameters.
SET UP ERASE/ERASE
Preprogram operation is not required prior to the erase
operation. A sequence of commands is required to
performacompleteeraseoperation:setuperase,erase,
and erase verify. High voltage is applied to the V PP pin
(VPP=VPPH).Thecommand20Hiswrittentothecommand
register to initiate the set-up erase mode.
ERASE OPERATION
The same command, 20H, is again written to the
command register. This second command starts bulk
REV. 0.6, OCT. 04, 2001
P/N: PM0767
6
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