Programmable bus hold circuit and method of using the same
AssigneeCypress Semiconductor Corporation
InventorsAnita X. Meng, Roger Bettman, Barry Loveridge
Life of this patent
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Abstract
A programmable bus hold circuit which may find application in programmable logic devices, memories and other I/O devices may include a first element for receiving a voltage from an I/O pad and programmable circuitry coupled to the first element for controlling whether the voltage at the pad is to be held its current logic level. The first element may be a logic gate (such as a NOR gate) the programmable circuit may include a tristatable buffer (e.g., under the control of a memory cell or other programmable bit capable of enabling or disabling the programmable bus hold circuit) or a switch (e.g., a transistor).
Claims16
A bus hold circuit comprising:
- a first element for receiving a voltage having a first logic level from an input/output pad;
- and a programmable tri-state buffer circuit coupled to the first element in a feedback path from the first element to the input/output pad for controlling whether the voltage at the input/output pad is held at the first logic level or is tri-stated.
A method comprising programming a tri-state buffer included as part of a feedback path of a bus hold circuit to hold or tri-state a voltage at an input/output pad.
A bus hold circuit, comprising a feedback path including a programmable tri-state buffer coupled to an output of the circuit.
Dependencies are inferred from the claim text.