M29W640FT datasheet(13/71 Pages) NUMONYX

13 / 71 page

M29W640FT, M29W640FB

Signal descriptions

13/71

2.9

Reset/Block Temporary Unprotect (RP)

The Reset/Block Temporary Unprotect pin can be used to apply a Hardware Reset to the

memory or to temporarily unprotect all Blocks that have been protected.

Note that if VPP/WP is at VIL, then the two outermost boot blocks will remain protected even

if RP is at VID.

A Hardware Reset is achieved by holding Reset/Block Temporary Unprotect Low, VIL, for at

least tPLPX. After Reset/Block Temporary Unprotect goes High, VIH, the memory will be

ready for Bus Read and Bus Write operations after tPHEL or tRHEL, whichever occurs last.

See the Ready/Busy Output section, Table 17: Reset/Block Temporary Unprotect AC

characteristics and Figure 12: Reset/Block Temporary Unprotect AC waveforms, for more

details.

Holding RP at VID will temporarily unprotect the protected Blocks in the memory. Program

and Erase operations on all blocks will be possible. The transition from VIH to VID must be

slower than tPHPHH.

2.10

Ready/Busy Output (RB)

The Ready/Busy pin is an open-drain output that can be used to identify when the device is

performing a Program or Erase operation. During Program or Erase operations Ready/Busy

is Low, VOL. Ready/Busy is high-impedance during Read mode, Auto Select mode and

Erase Suspend mode.

After a Hardware Reset, Bus Read and Bus Write operations cannot begin until Ready/Busy

becomes high-impedance. See Table 17: Reset/Block Temporary Unprotect AC

characteristics and Figure 12: Reset/Block Temporary Unprotect AC waveforms, for more

details.

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.

2.11

Byte/Word Organization Select (BYTE)

The Byte/Word Organization Select pin is used to switch between the x8 and x16 Bus

modes of the memory. When Byte/Word Organization Select is Low, VIL, the memory is in

x8 mode, when it is High, VIH, the memory is in x16 mode.

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