Abstract: An optoisolator device is shown having a die attachment device with a planar surface. A first circuit die has first and second planar surfaces and a first side surface. A receiver circuit and a first photodiode are formed on the first planar surface of the first circuit die, where the first photodiode is electrically coupled to the receiver circuit. The second planar surface of the first circuit die is attached to the planar surface of the die attachment device. A second circuit die has a transmitter circuit that includes a first light emitting diode and is attached to the die attachment device in a position adjacent to the first side surface of the first circuit die. A clear plastic layer is formed on the planar surface of the die attachment device over the first and second circuit dies. An opaque layer may be formed over the clear plastic layer.

Abstract: A ring detect circuit is shown that includes a regenerative latch configured to be coupled to a telephone line. The regenerative latch is configured to generate a fast transient signal in response to a ring signal on the telephone line. The latch is coupled to an isolation transformer through a capacitor. The fast transient passes across the capacitor and through the transformer. A comparator detects the fast transient and, responsive thereto, generates a ring detect signal.

Abstract: A hybrid circuit for use with a transformer includes a differential transmit amplifier having first and second input terminals for receiving a signal to be transmitted and a pair of output terminals that may be coupled to the transformer. The hybrid circuit also includes a summing node receive amplifier having an input terminal that may be coupled to the transformer and an output terminal that is accessible external to the hybrid circuit. The differential transformer provides for improved transmit amplitude when a low supply voltage is used. The externally accessible output of the summing node receive amplifier provides for adjustment of the receive gain to improve dynamic range and for tuning of the hybrid for different circuit requirements.

Abstract: Disclosed is a switch driver circuit is shown where the circuit can control current driven devices and drive devices across a capacitive barrier. A mode control signal determines whether the circuit is in a current mode or a capacitive mode. In current mode, the circuit provides a current output signal at an output of the circuit in response to a subject signal, such as an ON switch control signal for a hook switch application. In capacitive mode, the circuit provides a clocked output signal at the output of the circuit in response to the subject signal, such that the clocked output signal can pass across a capacitive isolation barrier.