PURPOSE: To improve a stability of tripping threshold value of an output signal and operating range controllability by providing a threshold value detection circuit for detecting a low threshold voltage without being affected by the change of a reference voltage.
CONSTITUTION: A comparator 3 has a stable reference voltage RIF to be held at an input terminal regardless of supply voltage and temperature. By using this stable voltage reference, the tripping threshold value of the comparator 3 can be exactly set. In a normal operating state, an output signal VCCLOW from the comparator 3 is zero but when a supply voltage Vdd is reduced lower than a tripping level or a concerned circuit is turned into about 2.5V or deep power down state, for example, the voltage is increased to a voltage value Vu on a power supply line 2. Respective elements are provided with MOS transistors to be controlled by a signal PWDN according to the negative logic obtained from the external signal PWD through a negator N1. Thus, the stability of the tripping threshold value and the operation controllability can be improved.
OLIVO MARCO (IT)
GOLLA CARLA (IT)
| JPH04221497A | 1992-08-11 |
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