VLKO is the lock-out voltage of the core power supply (VCC). The intention of VLKO is to make sure that device is on expected VCC level before program/erase to avoid unintentional program/erase operation during VCC power-up and down transitions. When VCC is below VLKO, the entire flash memory array is protected against a program or erase operation. This ensures that no spurious alteration of the memory content can occur during power transition.
VLKO is a single-value threshold parameter; every device has a different VLKO. Min/Max is an estimated range of VLKO. All the devices have VLKO within this range.
During power-down or when VCC drops below VLKO, the VCC and VIO voltages must drop below the VCC Reset (VRST) minimum for a period of tPD for the part to initialize correctly when VCC and VIO again rise to their operating ranges. See Figure 1.
In system implementation, you should use the maximum value for VLKO in all devices. For example, monitor VCC; if it drops below VLKO(max), make sure that VCC and VIO voltages drop below the VCC Reset (VRST) minimum for a period of tPD so that the device is correctly initialized.
Figure 1 Power down and voltage drop
Figure 1 shows the power down and voltage drop diagram and VLKO. See Figure 10 in S29GL01G/512T datasheet Rev.L.
This diagram applies to all Infineon GL series Parallel NOR flash families.