Koninklijke Philips Corporation N.V.

Nxp B.v.

Martijn Bredius

Peter G Steeneken

Hendrik Boezen

Klaas-Jan De Langen

Rameswor Shrestha

Balwinder Singh

In one embodiment, a method of communicating data values over a three conductor interface is provided. Different data values are transmitted by generating and transmitting three respective signals to a receiver using three conductors. The first signal is maintained as a set voltage level. The second signal is alternated between a high voltage and a low voltage according to a carrier frequency. The third signal is alternated between the high and low voltages and is out of phased with the second signal. To transmit a first data value, the first signal is generated on a first conductor, the second signal is generated on a second conductor, and the third signal is generated on a third conductor. To transmit a second data value, the second signal is generated on the first conductor, the first signal is generated on the second conductor, and the third signal is generated on the third conductor.

Capacitive isolated voltage domains

In one embodiment, a device includes a first IC having a differential signal driver and a first isolation circuit configured to provide differential signals transmitted by the differential signal driver to a first pair of bond pads of the first IC. First and second bond wires are configured to provide differential signals from the first pair of bond pads to a second pair of bond pad included in a second IC. The second IC includes a second isolation circuit configured to provide differential signals from the second pair of bond pads to a differential receiver circuit of the second IC. The bond wires are specifically arranged such that a distance between the first and second bond wires varies by at least 10% as measured at two points along a length of the first bond wire.

Bond wire arrangement for efficient signal transmission

A current-limited low-impedance return path is provided between an isolated bus system and the primary supply that provides this isolated bus system. In a preferred embodiment, a voltage follower circuit with an input at ground potential supplies a controlled zero-voltage to a center-tap on the load side of an isolation transformer. This voltage follower circuit provides a low-impedance path for unbalanced communications signals, but is configured to present a high-impedance, or current-limited, path to short-circuit currents. In this manner, the commonmode voltage changes that are caused by parasitic currents between the primary supply and the isolated bus system are minimized by providing the low-impedance path for these currents, and the isolation is maintained by providing the high-impedance path for short-circuit currents.

EMI reduction for isolated bus systems

A driving circuit provides a symmetric differential driving signal relative to one set of voltage potentials to a driver circuit that drives an output node to another set of voltage potentials. The differential driving signals from the driving system are equal and opposite to each other, thereby avoiding stray current flow between the driving system and the driven current mirrors. The transistors that provide the driving signal are continuously biased, using a weak bias in one logic state and stronger bias in the other state, to avoid hard-switching transients.

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San Jose, CA, United States of America

Martijn Bredius