8.4.1.1 POWER ON RESET (POR)

When initially powering up the BQ76925 device, the voltage on the BAT pin must exceed V_POR (4.7-V maximum) before the device will turn on. Following this, the device will remain operational as long as the voltage on BAT remains above V_SHUT (3.6-V maximum). If the BAT voltage falls below V_SHUT, the device will shut down. Recovery from shutdown occurs when BAT rises back above the V_POR threshold and is equivalent to a POR. The V_POR threshold following a shutdown depends on the minimum level reached by BAT after crossing below V_SHUT. If BAT does not fall below approximately 1.4 V, a higher V_POR (7.5-V maximum) applies. This is illustrated in Figure 12.

Figure 12. Power On State vs V_BAT

Following a power on reset, all volatile registers assume their default state. Therefore, care must be taken that transients on the BAT pin during normal operation do not fall below V_SHUT. To avoid this condition in systems subject to extreme transients or brown-outs, a hold-up circuit such as the one shown in the functional diagram is recommended. When using a hold-up circuit, care must be taken to observe the BAT to VC6 maximum ratings.