| 摘要 |
PROBLEM TO BE SOLVED: To contrive the protection of breakdown strength of a group of LSIs in a system, and protect the LSIs from breakage, by putting the device in such circuit constitution that is keeps the potential difference between heterogeneous power sources especially at power break of a heterogeneous power-source mixed system at a roughly constant low potential difference. SOLUTION: The power sequence circuit of a heterogeneous power system, which applies a plurality of power sources to a group of LSIs or breaks them, has each voltage regulator 2 and 3 which generates a superordinate power source VCC2 and a subordinate power source VCC3 from the highest-order power source VCC1, and power source level detectors 13 and 14 which receives the input of the voltage of the superordinate power source line or the highest- order power source line. Then, a MOS switch 5, a current limiting resistor 8, and a diode 13 are connected in series between the superordinate power source line and the subordinate power source line, and a MOS switch 6, a resistor 10 for charge currents, and an earth terminal are connected in series to the superordinate power source line, and the ON-OFF control of each MOS switch is performed, using the detection signal of each power level detector, and each power voltage is discharged in parallel. |
