Abstract To provide reduced vulnerability to glitches, a self switching bidirectional digital line driver comprises two identical circuits (10; 20), coupled in opposite senses between interface nodes (11, 21) and comprising a receiver (12; 22), a NOR gate (13; 23) and a transmitter (20; 15) and a transmitter connected in series. The output (14; 24) of each gate supplies an input to the other gate directly and via a latch (16; 26), resettable by the output of the opposing receiver. Each transmitter has one relaxed mode preferably provided by an open collector transistor and the logic is such that from a rest state corresponding to both transmitters being in the relaxed mode, the switching of one gate locks the other gate into the relaxed mode.
A self-switching bidirectional digital line driver adapted to interface between two logically biassed external environments (5;7;8: 5';7';8') characterized in that the driver comprises two similar circuits (10;20) connected in parallel but in opposite senses between the external environment interfacts (11;21), each circuit having input logic (13;23) and an output element (25;15) having one relaxed mode, the input logic of each circuit being symmetrically cross-coupled, directly and via a latch (16:26), output to input.
Claim 2
Dependent Claim
73 words
A self-switching bidirectional digital line driver adapted to interface between two logically biassed external environments (5;7;8: 5';7';8') characterized in that the driver comprises two similar circuits (10;20) connected in parallel but in opposite senses between the external environment interfacts (11;21), each circuit having input logic (13;23) and an output element (25;15) having one relaxed mode, the input logic of each circuit being symmetrically cross-coupled, directly and via a latch (16:26), output to input.
Claim 3
Dependent Claim
35 words
A driver as claimed in claim 1 characterized in that the input logic performs the NOR function of the input and the two cross-coupling signals, the input providing the resetting signal for the latched cross-coupling.
Claim 4
Dependent Claim
44 words
A driver as claimed in either preceding claim characterized in that each output element incorporates an open collector transistor (T51) and each input logic is coupled to its appropriate interface via a receiver (12;22) adapted to provide an acceptable input signal to the logic.
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