| 摘要 |
The adjustable start-up circuits basically include a sensor, a reference voltage, two stacked PMOS transistors, two stacked NMOS transistors, and a feedback line. The sensor compares a feedback voltage with a reference voltage. If the sensing voltage does not reach the reference voltage, the output voltage of the sensor turns on the corresponding transistor, which provides a current to its output until the voltage at feedback reaches the reference voltage. The time to reach the expected output voltage level at a load is simply equal to the charge stored at the load divided by the current, which can be scaled by a device aspect ratio of the transistor. Consequently, all adjustable start-up circuits provide an adjustable initial output voltage level closer to the output voltage level that reaches the equilibrium according to schedule. In addition, the output voltage level is varied by changing the reference voltage level.
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