M29KW032E datasheet(7/30 Pages) STMICROELECTRONICS

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M29KW032E

SIGNAL DESCRIPTIONS

See Figure 2, Logic Diagram, and Table 1, Signal

Names, for a brief overview of the signals connect-

ed to this device.

Address Inputs (A0-A20). The Address Inputs

select the cells in the memory array to access dur-

ing Bus Read operations. During Bus Write opera-

tions they control the commands sent to the

Command Interface of the Program/Erase Con-

troller.

Data Inputs/Outputs (DQ0-DQ7). The Data In-

puts/Outputs outputs the data stored at the select-

ed address during a Bus Read operation. During

Bus Write operations they represent the com-

mands sent to the Command Interface of the Pro-

gram/Erase Controller.

Data Inputs/Outputs (DQ8-DQ15). The Data In-

puts/Outputs output the data stored at the selected

address during a Bus Read operation. During Bus

Write operations the Command Register does not

use these bits. When reading the Status Register

these bits should be ignored.

Chip Enable (E). The Chip Enable, E, activates

the memory, allowing Bus Read and Bus Write op-

erations to be performed. When Chip Enable is

High, VIH, all other pins are ignored.

Output Enable (G). The Output Enable, G, con-

trols the Bus Read operation of the memory.

Write Enable (W). The Write Enable, W, controls

the Bus Write operation of the memory’s Com-

mand Interface.

Reset (RP). The Reset pin can be used to apply

a Hardware Reset to the memory.

A Hardware Reset is achieved by holding Reset

Low, VIL, for at least tPLPX. After Reset goes High,

VIH, the memory will be ready for Bus Read and

Bus Write operations after tPHEL or tRHEL, which-

ever occurs last. See the Ready/Busy Output sec-

tion,

Table

and

Figure

13,

Reset

Characteristics for more details.

Ready/Busy Output (RB). The Ready/Busy pin

is an open-drain output that can be used to identify

when the memory array can be read. Ready/Busy

is high-impedance during Read mode and Auto

Select mode. After a Hardware Reset, Bus Read

and Bus Write operations cannot begin until

Ready/Busy becomes high-impedance. See Table

16 and Figure 13, Reset AC Characteristics.

During Program or Erase operations Ready/Busy

is Low, VOL. Ready/Busy will remain Low during

Read/Reset commands or Hardware Resets until

the memory is ready to enter Read mode.

The use of an open-drain output allows the Ready/

Busy pins from several memories to be connected

to a single pull-up resistor. A Low will then indicate

that one, or more, of the memories is busy.

VCC Supply Voltage. The VCC Supply Voltage

supplies the power for Read operations.

The Command Interface is disabled when the VCC

Supply Voltage is less than the Lockout Voltage,

VLKO. This prevents Bus Write operations from ac-

cidentally damaging the data during power up,

power down and power surges. If the Program/

Erase Controller is programming or erasing during

this time then the operation aborts and the memo-

ry contents being altered will be invalid.

A 0.1µF capacitor should be connected between

the VCC Supply Voltage pin and the VSS Ground

pin to decouple the current surges from the power

supply. The PCB track widths must be sufficient to

carry the currents required during program and

erase operations, ICC3.

VPP Program Supply Voltage. VPP is both a

power supply and Write Protect pin. The two func-

tions are selected by the voltage range applied to

the pin. The Supply Voltage VCC must be applied

before the Program Supply Voltage VPP.

If VPP is in the range 11.4V to 12.6V it acts as a

power supply pin for program and erase opera-

tions. VPP must be stable until the Program/Erase

algorithm is completed.

If VPP is kept in a low voltage range (0V to 3.6V)

VPP is seen as a Write Protect pin. In this case a

voltage lower than VHH gives an absolute protec-

tion against program or erase, while VPP in the

range of VHH enables these functions (see Table

12, DC Characteristics for the relevant values).

Note that VPP must not be left floating or uncon-

nected as the device may become unreliable.

Vss Ground. The VSS Ground is the reference

for all voltage measurements.

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