| 摘要 |
<p>PURPOSE:To enhance the reliability of the title circuits by a method wherein a voltage output circuit and a signal detection circuit are installed, a dummy field-effect transis tor for current detection is connected to a voltage supply line in a part whose voltage is to be detected, a voltage which is lower than its voltage is output to the signal detection circuit and a voltage output is controlled widely. CONSTITUTION:A voltage V1 is converted into a lower voltage (V2 V1) by means of a level conversion circuit 21 between a point PI to be detected and a grounding line GND; it is output to a signal detection circuit 22. The low voltage is output to the signal detection circuit 22 by means of a MOSFET 23. In the FET 23, an electric current flows to a back gate from the point P1 to be detected; a voltage drop is caused in a resistance R11; a piece of detection information is output to the circuit 22 together with the voltage V2. As a result, when a gate voltage Vg1 at the FET 23 is controlled so as to be variable, a voltage can be controlled in such a way that a break voltage VBD at a gate junction is VBD BDO+Vg1. Consequently, even when a threshold voltage for a transistor constituting a first voltage detection circuit is irregular, the second voltage V2 as a voltage to be compared can be output with good stability when the gate voltage Vg1 is controlled so as to be variable.</p> |
