M29F102BB datasheet(7/24 Pages) STMICROELECTRONICS

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M29F102BB

BUS OPERATIONS

There are five standard bus operations that control

the device. These are Bus Read, Bus Write, Out-

put Disable, Standby and Automatic Standby. See

Table 3., Bus Operations, for a summary. Typical-

ly glitches of less than 5ns on Chip Enable or Write

Enable are ignored by the memory and do not af-

fect bus operations.

Bus Read. Bus Read operations read from the

memory cells, or specific registers in the Com-

mand Interface. A valid Bus Read operation in-

volves setting the desired address on the Address

Inputs, applying a Low signal, VIL, to Chip Enable

and Output Enable and keeping Write Enable

High, VIH. The Data Inputs/Outputs will output the

value, see Figure 9., Read Mode AC Waveforms,

and Table 11., Read AC Characteristics (TA = 0 to

70°C), for details of when the output becomes val-

id.

Bus Write. Bus Write operations write to the

Command Interface. A valid Bus Write operation

begins by setting the desired address on the Ad-

dress Inputs. The Address Inputs are latched by

the Command Interface on the falling edge of Chip

Enable or Write Enable, whichever occurs last.

The Data Inputs/Outputs are latched by the Com-

mand Interface on the rising edge of Chip Enable

or Write Enable, whichever occurs first. Output En-

able must remain High, VIH, during the whole Bus

Write operation. See Figures 10 and 11, Write AC

Waveforms, and Tables 12 and 13, Write AC

Characteristics, for details of the timing require-

ments.

Output Disable. The Data Inputs/Outputs are in

the high impedance state when Output Enable is

High, VIH.

Standby. When Chip Enable is High, VIH, the

memory enters Standby mode and the Data In-

puts/Outputs pins are placed in the high-imped-

ance state. To reduce the Supply Current to the

Standby Supply Current, ICC2, Chip Enable should

be held within VCC ± 0.2V. For the Standby current

level see Table 10., DC Characteristics (TA = 0 to

70°C).

During program or erase operations the memory

will continue to use the Program/Erase Supply

Current, ICC3, for Program or Erase operations un-

til the operation completes.

Automatic Standby. If CMOS levels (VCC ± 0.2V)

are used to drive the bus and the bus is inactive for

150ns or more the memory enters Automatic

Standby where the internal Supply Current is re-

duced to the Standby Supply Current, ICC2. The

Data Inputs/Outputs will still output data if a Bus

Read operation is in progress.

Special Bus Operations

Additional bus operations can be performed to

read the Electronic Signature and also to apply

and remove Block Protection. These bus opera-

tions are intended for use by programming equip-

ment and are not usually used in applications.

They require VID to be applied to some pins.

Electronic Signature. The

memory

has

two

codes, the manufacturer code and the device

code, that can be read to identify the memory.

These codes can be read by applying the signals

listed in Table 3., Bus Operations.

Block Protection and Blocks Unprotection. Each

block can be separately protected against acci-

dental Program or Erase. Protected blocks can be

unprotected to allow data to be changed.

There are two methods available for protecting

and unprotecting the blocks, one for use on pro-

gramming equipment and the other for in-system

use. For further information refer to Application

Note AN1122, Applying Protection and Unprotec-

tion to M29 Series Flash.

Table 3. Bus Operations

Note: 1. X = VIL or VIH.

Operation

Address Inputs

Data

Inputs/Outputs

Bus Read

VIL

VIH

Cell Address

Data Output

Bus Write

VIL

VIH

VIL

Command Address

Data Input

Output Disable

VIH

Hi-Z

Standby

VIH

Hi-Z

Read Manufacturer

Code

VIL

VIH

A0 = VIL, A1 = VIL, A9 = VID,

Others VIL or VIH

0020h

Read Device Code

VIL

VIH

A0 = VIH, A1 = VIL, A9 = VID,

Others VIL or VIH

0097h

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