Importance

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Abstract

A dual mode high voltage coupler is described for enabling a low current capacity high voltage generator to supply high voltage to an output load, such as a row or word line in an EEPROM memory device during a nonvolatile write or erase operation. The coupler limits the amount of current to defective cells or rows in the memory without limiting current to the cells and rows that are operating normally. In a first mode, a single stage charge pump, including a storage capacitor driven by a periodic voltage signal, develops a metered current through a diode to the output load whose amplitude is equal to the product of the capacitance of the storage capacitor, the change in voltage across the capacitor in each cycle of said periodic signal and the frequency of said signal. In a second mode, said high voltage is coupled directly to said output load without limiting the current whenever the voltage across said load exceeds a predetermined value.

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First Claim