| 摘要 |
PURPOSE:To miniaturize a smoothing capacitor forming a small potential by connecting another transistor (TR) for potential conversion in parallel with an MOS TR for converting potential in which a prescribed reference potential is given to its gate. CONSTITUTION:A DMOS TR17 is connected in parallel with an MOS TR12. A function circuit 15 generates a control signal S1 in response to its current consumption and the signal is supplied to a gate of the TR17. The TR17 is set to ON-state when the signal S1 is at ground potential and its source potential, that is, the potential of a node 16 is a VCC2, then constant, and when the signal S1 is at VCC2 by setting its threshold voltage. That is, the following relation is given to VTD to be satisfied, where VTD is the threshold voltage: -(VR-VT)< VTD<0V, where VCC2=VR-VT. On the other hand, the function circuit 15 sets the signal S1 to H level, i.e., the potential of VCC2 as its current consumption increases.
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