M50FLW040A datasheet(16/64 Pages) STMICROELECTRONICS

16 / 64 page

Signal descriptions

M50FLW040A, M50FLW040B

16/64

2.2.6

Ready/Busy output (RB)

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

Ready/Busy is Low, VOL, the device is busy with a program or erase operation, and it will not

accept any additional program or erase command (except for 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 is to prevent 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, the operation aborts, and the memory contents

that were 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 Program (see the Quadruple

Byte Program command description in A/A Mux interface and the Double/Quadruple Byte

Program command description in FWH mode) and Fast Erase options of the memory.

When VPP = VCC, program and erase operations take place as normal. When VPP = VPPH,

Fast Program and 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.

M50FLW040A Datasheet(PDF) 16 Page - STMicroelectronics