Method and apparatus for galvanically isolating two integrated circuits from each other
First Claim
1. An isolation circuit for providing dc isolation between two circuits that may be referenced to different ground potentials, comprising:
- an output buffer in one of said circuits connected to deliver a data signal to an output node, said data signal having a first voltage level and a second voltage level representing a first logic level and a second logic level, respectively;
an input buffer in another of said circuits connected to receive said data signal on an input node; and
a capacitance connected between said output and input nodes;
said input buffer comprising a circuit for maintaining a last voltage level asserted at said input node and for resisting a charge leakage from said capacitance.
1 Assignment
0 Petitions
Accused Products
Abstract
An isolation circuit (10) and method for providing dc isolation between two integrated circuit devices (11) and (12) that may be referenced to different ground potentials is presented. The isolation circuit (10) includes, in each circuit, an output buffer (20, 20'"'"') connected to deliver a signal to an input/output pin (16, 17) of the circuit (11, 12) with which the output buffer is associated. A capacitance (30), which may be a single capacitor or a combination of capacitors, is connected to the pins (16, 17) of each of the circuits (11, 12), and in each circuit (11, 12), an input buffer (22, 22'"'"') is connected to receive a signal delivered onto the I/O pin (16, 17). The input buffer (22, 22'"'"') includes a circuit for resisting a charge leakage from the capacitor, which, preferably is a bus holder circuit (36), or the like. In another embodiment, a transformer (85) is used to provide dc isolation between the two integrated circuits (62, 64).
-
Citations
20 Claims
-
1. An isolation circuit for providing dc isolation between two circuits that may be referenced to different ground potentials, comprising:
-
an output buffer in one of said circuits connected to deliver a data signal to an output node, said data signal having a first voltage level and a second voltage level representing a first logic level and a second logic level, respectively; an input buffer in another of said circuits connected to receive said data signal on an input node; and a capacitance connected between said output and input nodes; said input buffer comprising a circuit for maintaining a last voltage level asserted at said input node and for resisting a charge leakage from said capacitance. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
-
-
14. A method for providing dc isolation between a first circuit from a second circuit, wherein a ground potential of said first circuit may be different from a ground potential of said second circuit, comprising:
-
connecting a capacitance between a signal output node of said first circuit and a signal input node of said second circuit; providing a signal output buffer in said first circuit having an output connected to said output node for sourcing an signal output having a first voltage level and a second voltage level representing a first logic state and a second logic state, respectively; providing a signal input buffer in said second circuit connected to said input node, said signal input buffer being constructed to hold a last asserted voltage level at said input of said input buffer despite charge leakage from said capacitance. - View Dependent Claims (15, 16, 17, 18, 19, 20)
-
Specification