M50FW040 datasheet(15/53 Pages) STMICROELECTRONICS

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M50FW040

Signal descriptions

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2.2.6

Ready/Busy Output (RB)

The Ready/Busy pin gives the status of the memory’s Program/Erase Controller. When

Ready/Busy is Low, VOL, the memory is busy with a Program or Erase operation and it will

not accept any additional Program or Erase command except the Program/Erase Suspend

command. When Ready/Busy is High, VOH, the memory is ready for any Read, Program or

Erase operation.

2.3

Supply signal descriptions

The Supply Signals are the same for both interfaces.

2.3.1

VCC supply voltage

The VCC Supply Voltage supplies the power for all operations (Read, Program, Erase etc.).

The Command Interface is disabled when the VCC Supply Voltage is less than the Lockout

Voltage, VLKO. This prevents Bus Write operations from accidentally 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 memory contents

being altered will be invalid. After VCC becomes valid the Command Interface is reset to

Read mode.

A 0.1µF capacitor should be connected between the VCC Supply Voltage pins and the VSS

Ground pin to decouple the current surges from the power supply. Both VCC Supply Voltage

pins must be connected to the power supply. The PCB track widths must be sufficient to

carry the currents required during program and erase operations.

2.3.2

VPP optional supply voltage

The VPP Optional Supply Voltage pin is used to select the Fast Erase option of the memory

and to protect the memory. When VPP < VPPLK Program and Erase operations cannot be

performed and an error is reported in the Status Register if an attempt to change the

memory contents is made. When VPP = VCC Program and Erase operations take place as

normal. When VPP = VPPH Fast Erase operations are used. Any other voltage input to VPP

will result in undefined behavior and should not be used.

VPP should not be set to VPPH for more than 80 hours during the life of the memory.

2.3.3

VSS ground

VSS is the reference for all the voltage measurements.

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