System and method for switch status detection

Patent metadata

Field	Value
Publication number	US-2016178672-A1
Application number	US-201414573350-A
Country	US
Kind code	A1
Filing date	Dec 17, 2014
Priority date	Dec 17, 2014
Publication date	Jun 23, 2016
Grant date	—

Abstract

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 post 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.

First claim

What is claimed is:

1 . A system for determining a status of a switch having first and second terminals, the system comprising:
a first port configured to be coupled to the first terminal of the switch; a second port configured to be directly coupled to the second terminal of the switch, so that the second terminal of the switch constitutes a single electrical node; a capacitor coupled between the first port and ground; a comparator device having first and second input ports and an output port, wherein the first input port is 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, wherein the voltage source is configured to apply a first voltage to the second input port and the first voltage is relative to a second voltage experienced at the second port, wherein the comparator device is configured to provide an output signal at the output port that is indicative of whether the first voltage applied at the second input port is above or below a third voltage received at the first input port, the output signal at least sometimes being indicative of the status of the switch.

2 . The system of claim 1 , wherein the system is configured so that the system can achieve the determining of the status of the switch both in a first implementation in which the second port is grounded and in a second implementation in which the second port is other than grounded.

3 . The system of claim 2 , wherein the determining of the status of the switch can be performed when the second port is grounded or set to a different voltage that is either a supply voltage or a further voltage.

4 . The system of claim 3 , further comprising an additional terminal that is coupled directly to the second port and directly coupled to the second terminal of the switch, and wherein the additional terminal can be configured in various manners so that the second port is grounded, or set to the supply voltage, or set to the further voltage.

5 . The system of claim 1 , wherein the voltage source is a battery that provides a voltage differential between the first voltage and the second voltage.

6 . The system of claim 5 , wherein the system includes the switch and the switch is a single pole, single throw (SPST) switch, and wherein the capacitor is selectable from among a plurality of capacitors that can be coupled between the first port and ground.

7 . The system of claim 5 , wherein the current source includes one or more of a resistor and a current mirror, and wherein the system is implemented in an automotive application.

8 . The system of claim 1 , further comprising a resistor that couples tire first input port with the first port, and a diode linking the current source to a power source, and wherein the comparator device includes an operational amplifier.

9 . The system of claim 1 , further comprising a control component coupled to the output port and the current source, wherein the control component is configured to control the current source so that the current source intermittently drives current, wherein the control component includes one or more of a logic circuit and a microprocessor, and wherein the control component is configured so that, in at least one operational circumstance, the control component causes the current source to cease driving the current in response to reviving a first indication from the output port indicating that the third voltage applied to the first input port has changed from being less than the first voltage to being greater than the first voltage.

10 . The system of claim 9 , wherein the control component is further configured so that, in at least some additional operational circumstances, the control component refrains from causing the current source to drive any of the current in response to receiving a second indication from the output port indicating that the third voltage applied to the first input port is greater than the first voltage.

11 . The system of claim 9 , wherein the control component is further configured so that, in at least some additional operational circumstances, the control component causes the current source to continue driving the current for a full extent of a predetermined time period in response to receiving a second indication from the output port indicating throughout the predetermined time period that the third voltage applied to the first input port remains less then the first voltage.

12 . A circuit configured for interacting with a capacitor sod a switch in a manner allowing for determining a status of the switch, the switch having first and second terminals and the capacitor having a first node that is directly coupled to the first terminal of the switch, the circuit comprising:
a comparator device having first and second input ports and an output port, wherein the first input port is configured to be coupled at least indirectly to the first node; a current source coupled to the first input port; and a voltage source coupled between a second node and the second input port and configured to apply a first voltage to the second input port, the first voltage being relative to a second voltage of the second node, wherein the circuit is further configured so that the second node can be directly coupled to the second terminal of the switch so that the second voltage is also experienced by the second terminal, whereby the determining of the status of the switch can be achieved regardless of a level of the second voltage.

13 . The circuit of claim 12 , wherein the circuit is configured to achieve the determining of the status of the switch when the second voltage is other than grounded.

14 . The circuit of claim 12 , further comprising a diode linking the current source to a power source, wherein the comparator device includes an operational amplifier, wherein the current scarce includes one or more of a resistor and a current mirror, and wherein the first input port is coupled to the first node by way of a resistor.

15 . The circuit of claim 12 , further comprising a control component coupled to the output port and the current source,
wherein the control component is configured to control the current source so that the current source intermittently drives current toward the first node, and wherein the control component is configured so that, in at least one operational circumstance, the control component causes the current source to cease driving the current toward the first node in response to receiving a first indication from the output port indicating that an additional voltage received at the first input port has changed from being less than the first voltage to being greater than the first voltage.

16 . The circuit of claim 15 , wherein the control component includes one or more of a logic circuit and a microprocessor, and wherein the control component is further configured so that, in at least some additional operational circumstances, the control component one or both of (i) refrains from causing the current source to drive any of the current in response to receiving a second indication from the output port indicating that the additional voltage applied to the first input port is greater than the threshold voltage, or (ii) causes the current source to continue driving the current for a full extent of a predetermined time period in response to receiving a third indication from the output port indicating throughout the predetermined time period that the additional voltage applied to the first input port is less than the

Assignees

• Edwards William E
• Andresen Anthony F
• Freescale Semiconductor Inc

Inventors

• Edwards William E
• Andresen Anthony F

Classifications

• H01H9/167

  Circuits for remote indication · CPC title

• G01R31/3277

  of low voltage devices, e.g. domestic or industrial devices, such as motor protections, relays, rotation switches · CPC title

• G01R19/16576 Primary

  comparing DC or AC voltage with one threshold (G01R19/16514, G01R19/16519, G01R19/16528, G01R19/16533 and G01R19/1659 take precedence) · CPC title

• H01H9/16

  Indicators for switching condition, e.g. "on" or "off" · CPC title