Nxp Usa, Inc.

Freescale Semiconductor,inc.

Anthony F Andresen

William Ernest Edwards

Randall C Gray

The embodiments described herein provide systems and methods for determining the health status of a sensed switch. In general, the embodiments described herein determine a measure of a health status of the sensed switch by comparing a voltage on the sensed switch, ascertaining a first comparator state under one test condition and ascertaining a second comparator state under a second test condition. The first comparator state and the second comparator state are and then compared to determine the measure of the health status of the sensed switch.

Methods for switch health determination

A circuit for diagnostic testing includes a current source coupled to a power source and configured to provide wetting current along a path to a load control switch, a current sensor connected in series with the current source along the path, the current sensor being configured to generate a current sensor signal indicative of a current level along the path, a voltage measurement unit having an input terminal coupled to a node along the path through which the wetting current flows to reach the load control switch, the voltage measurement unit being configured to detect a state of the load control switch based on a voltage at the node, and a controller coupled to the current sensor and the voltage measurement unit, the controller being configured to determine a wetting current diagnostic condition in accordance with the current level and the detected state.

Wetting current diagnostics

Systems, methods, and circuits for determining one or more switch statuses are disclosed herein. In one example embodiment, such a system for determining a status of a switch having first and second terminals includes a first port configured to be coupled to the first terminal, a second port configured to be coupled to the second terminal, and a capacitor coupled between the first port and ground. Additionally, the system includes a comparator device having first and second input ports and an output port, the first input port being coupled at least indirectly to the first port, a current source coupled to the first input port, and a voltage source coupled between the second port and the second input port. The comparator device is configured to provide an output signal at the output port that is at least sometimes indicative of the status of the switch.

System and method for switch status detection

Systems, methods, and circuits for determining one or more switch statuses are disclosed herein. In one example embodiment, such a system includes a first port configured to be coupled to a switch, a capacitor, a comparator having first and second input ports and an output port, a current source coupled to the first input port, and a control component. The first input port is coupled to the first port and a threshold voltage if applied to the second input port. The control component is configured so that, in at least one circumstance, it causes the current source to cease driving the current in response to receiving an indication from the output port indicating that an additional voltage applied to the first input port has changed from being less than the threshold voltage to being greater than that voltage, the indication being indicative of the switch status.

A circuit includes an evaluation node through which current flows from a voltage source node to a sensed switch when the sensed switch is closed. First and second control switches are disposed between the voltage source node and the evaluation node to switch between first and second current paths for the current. The current passes through the first control switch when flowing along the first current path. The second control switch is coupled to a control terminal of the first control switch to deactivate the first control switch and allow the current to flow through the second current path. Multiple passive circuit elements are configured to establish first and second current levels for the current. The passive circuit elements are disposed between the voltage source node and the evaluation node in a circuit arrangement in which no current path to ground is present when the sensed switch is open.

Sensed switch current control

Systems and methods for switch health determination

A method of undervoltage detection includes detecting a voltage level for a power supply of a system, placing the system in an undervoltage state if the voltage level is below an undervoltage threshold, activating a load of the system at a first power level if the detected voltage level exceeds a first activation threshold and if the system resides in the undervoltage state, and activating the load at a second power level if the detected voltage level exceeds a second activation threshold.

State-based undervoltage hysteresis

A method of providing wetting current diagnostics for a load control switch includes changing test switch settings of a detection circuit from an operational configuration to a testing configuration. The test switch settings specify respective states of first and second test switches of the detection circuit. The first and second test switches are connected to a node of the detection circuit through which, in the operational configuration, a wetting current for the load control switch flows. The method includes determining whether a voltage at the node becomes no longer indicative of the operational configuration as a result of the changed test switch settings, returning the test switch settings to the operational configuration, and providing a wetting current fault indication if the voltage at the node fails to return to a level indicative of the operational configuration after returning the test switch settings to the operational configuration.

A method of switch detection is disclosed that comprises, enabling a low power mode on a switch detection device, activating a first detection circuit for detecting, at a first expiration of a first polling time interval, a first switch state of a first switch having a first priority level, the first switch state including one of a first open state and a first closed state, comparing the detected first switch state with a prior first switch state, and activating a second detection circuit for detecting, at a second expiration of a second polling time interval, a second switch state of a second switch having a second priority level, the second switch including one of a second open state and a second closed state, and the second polling time interval being greater than the first polling time interval, and the second priority level being different from the first priority level.

Growing community of inventors

Chandler, AZ, United States of America

Anthony F Andresen