Abstract: An optocoupler circuit includes a pulse generator which supplies a pulsed signal to the light-emitting device, while the pulsed signal has at least two different levels of which at least one of the levels is controllable. The pulsed signal is a combination of an input pulse signal and an input level signal. The light-emitting device produces an amount of light which depends on the levels of the pulsed signal. The photosensitive device supplies an output signal which depends on the amount of light received from the light-emitting device. A separation circuit receives the output signal and separates an output pulse signal therefrom, indicating an occurrence of a pulse of the input pulse signal, and an output level signal corresponding to a value of the at least one controllable level and thus to the input level signal.

Abstract: An optocoupler circuit comprises a pulse generator which supplies a pulsed signal to the light-emitting device, while the pulsed signal has at least two different levels of which at least one of the levels is controllable. The pulsed signal is a combination of an input pulse signal and an input level signal. The light-emitting device produces an amount of light which depends on the levels of the pulsed signal. The photosensitive device supplies an output signal which depends on the amount of light received from the light-emitting device. A separation circuit receives the output signal and separates an output pulse signal therefrom, indicating an occurrence of a pulse of the input pulse signal, and an output level signal corresponding to a value of the at least one controllable level and thus to the input level signal.

Abstract: An optocoupler driver circuit comprises an optocoupler (OC) with a light-emitting device (D) and a photosensitive device (T). A current source (CS) supplies a current (Is) to both the light-emitting device (D) and an impedance (Z). The ratio of the current (Id) through the light-emitting device (D) and the resulting current (Ic) through the photosensitive device (T) decreases if the temperature increases. The voltage (Vd) across the light-emitting device (D) also decreases if the temperature increases. The decrease of the voltage (Vd) across the light-emitting device (D) causes the current (Iz) through the impedance (Z) to decrease. Consequently, the current (Id) through the light-emitting device (D) increases and counteracts the decreasing ratio.