M29W160FB データシートの表示（PDF） - Numonyx -> Micron
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M29W160FB Datasheet PDF : 57 Pages
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M29W160FT, M29W160FB, M29W320FT, M29W320FB
Signal descriptions
2.7
Write Enable (W)
The Write Enable, W, controls the Bus Write operation of the memory’s command interface.
2.8
VPP/Write Protect (VPP/WP)
The VPP/Write Protect pin is only available in the M29W320FT/B devices. It provides two
functions. The VPP function allows the memory to use an external high voltage power supply
to reduce the time required for Unlock Bypass Program operations. The Write Protect
function provides a hardware method of protecting the 16 Kbyte Boot Block. The VPP/Write
Protect pin must not be left floating or unconnected.
When VPP/Write Protect is Low, VIL, the memory protects the 16 Kbyte Boot Block; Program
and Erase operations in this block are ignored while VPP/Write Protect is Low.
When VPP/Write Protect is High, VIH, the memory reverts to the previous protection status
of the 16 Kbyte boot block. Program and Erase operations can now modify the data in the 16
Kbyte Boot Block unless the block is protected using Block Protection.
When VPP/Write Protect is raised to VPP the memory automatically enters the Unlock
Bypass mode. When VPP/Write Protect returns to VIH or VIL normal operation resumes.
During Unlock Bypass Program operations the memory draws IPP from the pin to supply the
programming circuits. See the description of the Unlock Bypass command in the command
interface section. The transitions from VIH to VPP and from VPP to VIH must be slower than
tVHVPP, see Figure 16.
Never raise VPP/Write Protect to VPP from any mode except Read mode, otherwise the
memory may be left in an indeterminate state.
A 0.1 µF capacitor should be connected between the VPP/Write Protect 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 Unlock Bypass Program, IPP.
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.
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 Section 2.10: Ready/Busy Output (RB), Table 15 and Figure 15., 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.
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