| 摘要 |
A circuit includes a band-gap reference circuit and a start-up circuit coupled between an output and an input of the band-gap reference circuit. When the output of the band-gap reference circuit is below a start-up voltage threshold, the start-up circuit provides a first voltage at the input of the band-gap reference circuit which, in turn, causes the band-gap reference circuit to produce a desired voltage at the output. When the desired voltage has been reached, i.e., a voltage corresponding to the start-up voltage threshold, the start-up circuit turns off and does not interfere with the normal operation of the band-gap reference circuit. The start-up circuit may include first circuitry configured to produce a first voltage if a voltage signal at the output of the band-gap reference circuit is below the start-up voltage threshold. The start-up circuit may further include second circuitry coupled to the first circuitry and configured to produce a second voltage at the input of the band-gap reference circuit in response to the first voltage. The start-up voltage threshold may be a desirable output voltage, for example approximately 1.25 volts.
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