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M29F040B
valid data while old data is erased. Eachblock can
be protected independently to prevent accidental
Program or Erase commands from modifying the
memory. Program and Erase commands are written to the Command Interface of the memory. An
on-chip Program/Erase Controller simplifies the
process ofprogramming orerasing thememory by
taking care of all of the special operations that are
required to update the memory contents. The end
of a program or erase operation can be detected
and any error conditions identified. The command
set required to control the memory is consistent
with JEDEC standards.
Chip Enable, OutputEnable andWrite Enable signals control the bus operation of the memory.
They allow simple connection to most microprocessors, often without additional logic.
The memory is offered in TSOP32 (8 x 20mm),
PLCC32 and PDIP32 packages. Access times of
45ns, 55ns, 70ns and 90ns are available. The
memory is supplied with all the bits erased (set to
‘1’).
SIGNAL DESCRIPTIONS
See Figure 1, Logic Diagram, and Table 1, Signal
Names, for a brief overview of thesignals connected to this device.
Address Inputs (A0-A18). The Address Inputs
select the cells in the memory array to access during Bus Read operations. During BusWrite operations they control the commands sent to the
Command Interface of the internal state machine.
Data Inputs/Outputs (DQ0-DQ7). The Data Inputs/Outputs output thedata storedat the selected
address during a Bus Read operation. DuringBus
Write operations they represent the commands
sentto theCommand Interface ofthe internal state
machine.
Chip Enable (E). The Chip Enable, E, activates
the memory, allowing BusRead and Bus Write operations to be performed. When Chip Enable is
High, VIH, all other pins are ignored.
Output Enable (G). The Output Enable, G, controls the Bus Read operation of the memory.
Write Enable (W). The WriteEnable, W,controls
the Bus Write operation of the memory’s Command Interface.
VCCSupply Voltage. The VCCSupply Voltage
supplies the power for all operations (Read, Program, Erase etc.).
The Command Interface is disabledwhen the V
CC
Supply Voltage is less than the Lockout Voltage,
V
LKO
. Thisprevents Bus Write operationsfrom accidentally damaging the data during power up,
power down and power surges. If the Program/
Erase Controller is programming orerasing during
this time thenthe operation aborts and the memory contents being altered will be invalid.
A 0.1µF capacitor should be connected between
the VCCSupply Voltage pin and the VSSGround
pin to decouplethe current surges from the power
supply. The PCB track widthsmust be sufficient to
carry the currents required during program and
erase operations, I
CC4
.
VSSGround. The VSSGroundis thereference for
all voltage measurements.
Table 2. Absolute Maximum Ratings
(1)
Note: 1. Except for the rating ”Operating Temperature Range”, stresses above those listed in the Table ”Absolute Maximum Ratings” may
cause permanent damage to the device. These are stress ratings only and operation of the device atthese or any other conditions
above those indicated in the Operating sections of this specification is not implied. Exposure to Absolute Maximum Rating conditions forextended periods may affect device reliability. Refer also tothe STMicroelectronics SURE Program and other relevantquality documents.
2. Minimum Voltage may undershoot to –2V during transition andfor less than 20ns during transitions.
Symbol Parameter Value Unit
T
A
Ambient Operating Temperature (Temperature Range Option 1) 0 to 70 °C
Ambient Operating Temperature (Temperature Range Option 6) –40 to 85 °C
Ambient Operating Temperature (Temperature Range Option 3) –40 to 125 °C
T
BIAS
Temperature Under Bias –50 to 125 °C
T
STG
Storage Temperature –65 to 150 °C
V
IO
(2)
Input or Output Voltage –0.6 to 6 V
V
CC
Supply Voltage –0.6 to 6 V
V
ID
Identification Voltage –0.6 to 13.5 V