| 摘要 |
PURPOSE:To prevent latchup by providing 2 sets of analog switches using a gate of a transistor(TR) as a control terminal, connecting a resistor between one input and GND, connecting an external power supply to other input terminal, connecting output terminals, and controlling each by a control terminal. CONSTITUTION:A resistor 28 is provided between the emitter of a parasitic npn TR 18 and GND. When there is any difference in the rising of a power supply VDD and an external power supply VA, the parasitic PNP TR 19 starts it operation and its collector is going to supply a current to the base of the parasitic npn TR 18, but the resistor 28 is placed between the emitter of the TR 18 and the GND, the base-emitter potential rises and a resistor 23 of P-well acts like leaf cut and the TR 18 cannot be turned on. Thus, no latchup is caused. |
