User Manual

Apollo3 Blue Datasheet
DS-A3-0p9p1 Page 773 of 909 2019 Ambiq Micro, Inc.
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Figure 94. BLE/Burst Buck Ton Adjustment Diagram
20.3.2 BLE/Burst Buck zero length detect
In addition to the Ton adjustment, there is a zero length detect circuit to ensure the regulated voltage does
not drop out. The zero length detect is a mechanism to detect the length of time the buck is indicating that
the buck voltage is below a certain threshold. If the indicator is continuously asserted beyond a certain
time, this indicates that the Buck has not been able to pull the voltage above the threshold. The zero length
detect logic will send a flag to the reset generator logic. This will result in either a reset, or an interrupt. The
REG_MCU_CTRL_BO_DISABLE register (BODBRDE) controls the BLE/Burst buck local brown out
disables.