| 摘要 |
Power supply 100 supplying load 101 regulates voltage in a first mode by a first voltage regulator 105. When a fault is detected the supply 100 enters a second mode where voltage is regulated at a lower voltage level by a second regulator 111. If a second fault is not detected within a time interval the supply 100 is returned to the first mode. If a second fault is detected within the time interval the supply 100 may enter a power down mode, and may remain powered down pending a manual reset. The faults detected may include an over voltage condition and the second fault may comprise the second, lower voltage being outside a predetermined interval. The interval may be of a predetermined duration and may end when a condition of the power supply is detected. The second voltage may be sufficiently low either for the load 101 not to operate, or for it to operate with reduced functionality. Detection of the first fault may depend upon a characteristic such as a time duration since a previous fault detection, a repetition characteristic or a characteristic of the regulated voltage power, and may comprise a filter characteristic. The faults detected may include faults of the power supply such as an excess temperature of an output transistor. The power supply provides immunity from transient over-voltages without manual intervention and may be used to power, for example, a cellular communication system. |
