Write enable (W)
The write enable, W, controls the bus write operation of the memory’s command interface.
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
Section 2.9: Ready/busy output (RB), Table 15: Reset/block temporary unprotect AC
characteristics and Figure 14: Reset/block temporary unprotect AC waveforms, for more
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.
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
After a hardware reset, bus read and bus write operations cannot begin until ready/busy
becomes high-impedance. See Table 15: Reset/block temporary unprotect AC
characteristics and Figure 14: Reset/block temporary unprotect AC waveforms.
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.
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.
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 prevents 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 then the operation aborts and the memory contents
being altered will be invalid.