M29F400 Ver la hoja de datos (PDF) - STMicroelectronics
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M29F400 Datasheet PDF : 40 Pages
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M29F400BT, M29F400BB
Signal descriptions
2.7
Write Enable (W)
The Write Enable, W, controls the Bus Write operation of the memory’s Command Interface.
2.8
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.
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 15. and Figure 11., Reset/Temporary Unprotect
AC Characteristics 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.
2.9
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, 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 15. and Figure 11., Reset/Temporary Unprotect 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.
2.10
Byte/Word organization select (BYTE)
The Byte/Word Organization Select pin is used to switch between the 8-bit and 16-bit Bus
modes of the memory. When Byte/Word Organization Select is Low, VIL, the memory is in 8-
bit mode, when it is High, VIH, the memory is in 16-bit mode.
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