4.5.1.1 Device Reset

To prevent inadvertent write operations or any other spurious events from occurring during a power-up sequence, the AT34C04 includes a Power-on Reset (POR) circuit. Upon power-up, the device will not respond to any commands until the V_CC level crosses the internal voltage threshold (V_POR) 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 V_CC supply has reached a stable value greater than or equal to the minimum V_CC level. Additionally, once the V_CC is greater than or equal to the minimum V_CC level, the bus master must wait at least t_PUP before sending the first command to the device. See Table 4-4 for the values associated with these power-up parameters.

Before selecting the device and issuing protocol, a valid and stable supply voltage must be applied and no protocol should be issued to the device for the time specified by the t_INIT parameter. The supply voltage must remain stable and valid until the end of the protocol transmission, and for a write instruction, until the end of the internal write cycle.

Table 4-4. Power-Up Conditions⁽¹⁾
Symbol	Parameter	Min.	Max.	Units
t_POR	Power-on Reset Time	－	10.0	ms
V_POR	Power-on Reset Threshold Voltage	1.0	1.6	V
t_INIT	Time for Power-on to First Command	10.0	－	ms
t_POFF	Warm Power Cycle Off Time	1.0	－	ms

Note:

These parameters are characterized but they are not 100% tested in production.

If an event occurs in the system where the V_CC level supplied to the AT34C04 drops below the maximum V_POR level specified, it is recommended that a full-power cycle sequence be performed by first driving the V_CC pin to GND, waiting at least the minimum t_POFF time and then performing a new power-up sequence in compliance with the requirements defined in this section.

Figure 4-2. Power-Up Timing