Patent ID: 6563353
Filing Date: 2003-05-13
Classification: H03K

Abstract:
A power-on control circuit for an integrated circuit of the type having a first high voltage source, having a second high voltage source, and having an output buffer with a first input terminal and a second input terminal, wherein the voltage of the first high voltage source is higher than the voltage of the second high voltage source, comprising:a pull-down circuit connected between the first input terminal and a first reference voltage, and receiving a first signal; a pull-up circuit connected between the second input terminal and a second reference voltage, and receiving a second signal; a power-on detection circuit coupled to the first high voltage source and to the second high voltage source, and generating the first signal and the second signal, when the first high voltage source is powered on and the second high voltage is not powered on, the first signal enabling the pull-down circuit to make the first input terminal coupled to the first reference voltage and disabled, the second signal enabling the pull-up circuit to make the first input terminal coupled to the second reference voltage and disabled, such that an output terminal of the output buffer is at high impedance, and when the first high voltage source is powered on and the second high voltage is powered on, the first signal disabling the pull-down circuit, and the second signal disabling the pull-up circuit.