Patent ID: 6404609
Filing Date: 2002-06-11
Classification: H03K,H04B

Abstract:
A circuit having an intrinsically safe side and a non-intrinsically safe side, said circuit receives an input signal on said intrinsically safe side to switch an output signal on said non-intrinsically safe side between a high state and a low state, said circuit comprising:an optical coupler having a first conductive state of low impedance and a second conductive state of high impedance; an input on said intrinsically safe side that receives multi-state input signals to switch said optical coupler between said conductive states; said optical coupler is effective when in said first conductive state to apply a high potential signal to said output; said optical coupler is effective when in said second conductive state to apply a low potential signal to said output; said non-intrinsically safe side of said circuit comprises: a power supply; an output connectable to a data line; a first series circuit including a first resistor connected between a first side of the power supply and said output; said first series circuit is effective when said optical coupler is in said second conductive state to apply a current to said output in series with a load resistor to ground to generate a relatively low potential signal on said output; said non-intrinsically safe circuit further comprises: a second series circuit including a second resistor and an output side of said optical coupler connected between said first side of said power supply and said output; said second series circuit is effective when said optical coupler is in said first conductive state to apply a relatively high current to said load resistor via said output to apply a relatively high output signal to said output.