US 7,406,339 B2 · On-chip detection circuit off-chip mechanical switch's open and close actions

Abstract

An on-chip detection circuit automatically detects when an external switch has been activated. When the device is initialized, the detection circuit measures the operating current and coverts the information into an analog voltage. The analog voltage is then processed through an on-chip analog-to-digital converter and the digitized result is stored as a reference value. To sense the open and close action of the off-chip mechanical switch, the device then takes a sample of the operating current periodically, digitizes this information and compares the sampled value to the reference value. A change in value larger than some predetermined level indicates the external switch has been activated.

Claims21

Dependent claims

A device comprising:

a voltage generator configured to maintain a constant supply voltage at a port of the device independently of a state of a switch of an external circuit connected to the port;
a current monitor configured to sense, at the port, a current of the external circuit;
a converter configured to convert the sensed current to a digital value;
and
a comparator configured to compare the digital value to a reference value and to determine the switch has been actuated if the digital value differs from the reference value by at least a predetermined amount.

2 more elements

Dependencies are inferred from the claim text.

On-chip detection circuit off-chip mechanical switch's open and close actions

Life of this patent

On-chip detection circuit off-chip mechanical switch's open and close actions

Life of this patent

Abstract

Claims21