M29W320ET, M29W320EB
SIGNAL DESCRIPTIONS
See Figure 2., Logic Diagram, and Table
1., Signal Names, for a brief overview of the sig-
nals connected to this device.
Address Inputs (A0-A20). The Address Inputs
select the cells in the memory array to access dur-
ing Bus Read operations. During Bus Write opera-
tions they control the commands sent to the
Command Interface of the Program/Erase Con-
troller.
Data Inputs/Outputs (DQ0-DQ7). The Data I/O
outputs the data stored at the selected address
during a Bus Read operation. During Bus Write
operations they represent the commands sent to
the Command Interface of the Program/Erase
Controller.
Data Inputs/Outputs (DQ8-DQ14). The Data I/O
outputs the data stored at the selected address
during a Bus Read operation when BYTE is High,
VIH. When BYTE is Low, VIL, these pins are not
used and are high impedance. During Bus Write
operations the Command Register does not use
these bits. When reading the Status Register
these bits should be ignored.
ignored while VPP/Write Protect is Low, even when
RP is at VID.
When VPP/Write Protect is High, VIH, the memory
reverts to the previous protection status of the two
outermost boot blocks. Program and Erase oper-
ations can now modify the data in these blocks un-
less the blocks are protected using Block
Protection.
When VPP/Write Protect is raised to VPP the mem-
ory automatically enters the Unlock Bypass mode.
When VPP/Write Protect returns to VIH or VIL nor-
mal 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 17.
Never raise VPP/Write Protect to VPP from any
mode except Read mode, otherwise the memory
may be left in an indeterminate state.
The VPP/Write Protect pin must not be left floating
or unconnected or the device may become unreli-
able. A 0.1µF capacitor should be connected be-
tween 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
Data Input/Output or Address Input (DQ15A–1).
When BYTE is High, VIH, this pin behaves as a
Data Input/Output pin (as DQ8-DQ14). When
BYTE is Low, VIL, this pin behaves as an address
pin; DQ15A–1 Low will select the LSB of the ad-
dressed Word, DQ15A–1 High will select the MSB.
Throughout the text consider references to the
Data Input/Output to include this pin when BYTE is
High and references to the Address Inputs to in-
clude this pin when BYTE is Low except when
stated explicitly otherwise.
Unlock Bypass Program, IPP
.
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.
Chip Enable (E). The Chip Enable, E, activates
the memory, allowing Bus Read and Bus Write op-
erations to be performed. When Chip Enable is
High, VIH, all other pins are ignored.
Output Enable (G). The Output Enable, G, con-
trols the Bus Read operation of the memory.
Note that if VPP/WP is at VIL, then the two outer-
most 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 16. and Figure 16., 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
Write Enable (W). The Write Enable, W, controls
the Bus Write operation of the memory’s Com-
mand Interface.
V
PP/Write Protect (VPP/WP). The
VPP/Write
Protect pin provides two functions. The VPP func-
tion allows the memory to use an external high
voltage power supply to reduce the time required
for Program operations. This is achieved by by-
passing the unlock cycles and/or using the Double
Word or Quadruple Byte Program commands.
tPHPHH
.
The Write Protect function provides a hardware
method of protecting the two outermost boot
blocks. When VPP/Write Protect is Low, VIL, the
memory protects the two outermost boot blocks;
Program and Erase operations in these blocks are
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
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STMICROELECTRONICS [ ST ]
