| 摘要 |
An apparatus comprises a supply voltage divider, a state machine, two comparators and a threshold selector. The supply voltage divider divides a VCC into N states SK, and acquires the border voltages VK and VK+1 corresponding to the SK through a resistor divider. The threshold selector acquires a corresponding voltage VK from the supply voltage divider according to the current state SK outputted by the state machine and then sends the acquired VK as VH to a first comparator, and acquires a corresponding voltage VK+1 and sends the acquired VK+1 as VL to a second comparator. The state machine determines whether or not the VH and the VL are matched with the current state SK. If matched, the OSC of the state machine will be turned off, otherwise, the next state Sk+1 or Sk−1 of the SK will be outputted.
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