4.5.1.1 Device Reset

To prevent inadvertent write operations or any other spurious events from occurring during a power-up sequence, the AT24CSW04X/AT24CSW08X includes a Power-on Reset (POR) circuit. Upon power-up, the device will not respond to any commands until the VCC level crosses the internal voltage threshold (VPOR) that brings the device out of Reset and into Standby mode.

The system designer must ensure the instructions are not sent to the device until the VCC supply has reached a stable value greater than or equal to the minimum VCC level. Additionally, once the VCC is greater than or equal to the minimum VCC level, the bus master must wait at least tPUP before sending the first command to the device. See Table 4-4 for the values associated with these power-up parameters.

Table 4-4. Power-Up Conditions(1)
SymbolParameterMin.Max.Units
tPUPTime required after VCC is stable before the device can accept commands100µs
VPORPower-on Reset Threshold Voltage1.5V
tPOFFMinimum time at VCC = 0V between power cycles1ms
Note:
  1. These parameters are characterized but they are not 100% tested in production.

If an event occurs in the system where the VCC level supplied to the AT24CSW04X/AT24CSW08X drops below the maximum VPOR level specified, it is recommended that a full-power cycle sequence be performed by first driving the VCC pin to GND, waiting at least the minimum tPOFF time and then performing a new power-up sequence in compliance with the requirements defined in this section.