| 摘要 |
A level shifting circuit comprises a first low power, low speed level shifter 30 and a second high power, high speed level shifter stage 31. Both the stages 30, 31 have signal inputs connected to a common input IN for receiving signals, at least one of whose levels is to be shifted. The output of the first stage 30 is connected to an enable input EN2 of the second stage 31 and switches the operation of the second stage 31 between an enabled state and a disabled state in which the second stage 31 consumes little or no power. The first stage 30 has an enable input EN1 which may be permanently enabled.
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