Patent ID: 7167036

Claim:
An interface circuit for transforming a first signal varying between a low voltage and a high voltage into a second signal varying between a lower voltage and a higher voltage, the lower voltage being smaller than the low voltage or the higher voltage being greater than the high voltage, comprising: an inverter circuit receiving the first signal and being connected between a lower voltage source through first diodes and a higher voltage source through second diodes, each of the first diodes and each of the second diodes having a threshold voltage; a conversion and storage element formed of first and second inverters head-to-tail supplied between said higher and lower voltages, the first inverter receiving the output of the inverter circuit for providing the second signal; wherein the number of said first diodes and the number of said second diodes are such that the difference between the low voltage and the lower voltage is smaller than or equal to the sum of the threshold voltages of said first diodes or the difference between the higher voltage and the high voltage is smaller than or equal to the sum of the threshold voltages of said second diodes.