Circuit and Method of Over-Current Protection

Patent metadata

Field	Value
Publication number	US-2018294643-A1
Application number	US-201815948290-A
Country	US
Kind code	A1
Filing date	Apr 9, 2018
Priority date	Apr 7, 2017
Publication date	Oct 11, 2018
Grant date	—

Abstract

A method of over-current protection includes: determining a current flowing through a first element to be protected, comparing the determined current with a plurality of thresholds, controlling a counter based on the comparing the determined current with a plurality of thresholds, and stopping the current flowing through the first element by activating a switch in series with the first element when an output of the counter reaches a predetermined counter threshold.

First claim

What is claimed is:

1 . A method of over-current protection comprising:
determining a current flowing through a first element to be protected; comparing the determined current with a plurality of thresholds; controlling a counter based on the comparing the determined current with the plurality of thresholds; and stopping the current flowing through the first element by activating a switch in series with the first element when an output of the counter reaches a predetermined counter threshold.

2 . The method of claim 1 , wherein the counter overflows at the predetermined counter threshold.

3 . The method of claim 1 , further comprising comparing the output of the counter with the predetermined counter threshold, wherein the predetermined counter threshold is stored in a digital register.

4 . The method of claim 1 , wherein the determining the current flowing through the first element to be protected comprises measuring a voltage across a resistor coupled to the first element.

5 . The method of claim 1 , wherein the controlling the counter comprises:
configuring the counter to count down with a first speed when the determined current is below a first threshold; and configuring the counter to count up with a second speed when the determined current is above the first threshold.

6 . The method of claim 5 , wherein the first speed and the second speed are equal.

7 . The method of claim 5 , wherein the first speed is lower than the second speed.

8 . The method of claim 5 , wherein the controlling the counter further comprises:
configuring the counter to count up with a third speed greater than the second speed when the determined current is above a second threshold, the second threshold being higher than the first threshold.

9 . The method of claim 8 , wherein the third speed is higher than the second speed.

10 . The method of claim 1 , wherein the first element is a cable.

11 . A circuit comprising:
a current sensing circuit configured to sense a current through a first circuit device; a first comparator having a first input coupled to a first reference node and a second input coupled to the current sensing circuit; and a counter comprising a first control input coupled to an output of the first comparator, and an output configured to be coupled to a switch, the switch coupled in series with the current sensing circuit.

12 . The circuit of claim 11 , further comprising the first circuit device.

13 . The circuit of claim 11 , wherein the first circuit device is a cable.

14 . The circuit of claim 11 , wherein the current sensing circuit, the first comparator, and the counter are integrated inside an integrated circuit.

15 . The circuit of claim 11 , further comprising the switch.

16 . The circuit of claim 15 , wherein the current sensing circuit, the first comparator, the counter, and the switch are integrated inside an integrated circuit.

17 . The circuit of claim 15 , wherein
the switch is a mechanical relay; the counter has an accumulator with 23 bits; and the current sensing circuit comprises a resistor.

18 . The circuit of claim 15 , wherein the switch is a first transistor, and
wherein the current sensing circuit comprises a second transistor.

19 . The circuit of claim 18 , wherein the first transistor and the second transistor are the same transistor.

20 . The circuit of claim 11 , wherein the first control input selects between counting up or counting down.

21 . The circuit of claim 11 , wherein the first control input selects between a first step size and a second step size, the first step size being smaller than the second step size.

22 . The circuit of claim 11 , wherein the first control input selects between a first counting frequency and a second counting frequency, the first counting frequency being smaller than the second counting frequency.

23 . The circuit of claim 11 , further comprising:
a second reference node configured to be used as a reference voltage; and a second comparator coupled to the second reference node and to the current sensing circuit, the second comparator having a second comparator output, wherein the counter further comprises a second control input coupled to the second comparator output, wherein the first control input selects between counting up or counting down, and wherein the second control input selects between a first step size and a second step size, the first step size being smaller than the second step size.

24 . A method of emulating current capabilities of a cable, the method comprising:
monitoring a current flowing through the cable; comparing the current with a plurality of thresholds; controlling a counter based on the comparing the current with a plurality of thresholds; and determining that the current has exceeded the current capabilities of the cable when the counter reaches a predetermined counter threshold.

25 . The method of claim 24 , further comprising opening a switch in series with the cable when the counter reaches the predetermined counter threshold.

Assignees

• Infineon Technologies Ag

Inventors

• Donath Stephan

Classifications

• H02H1/0007

  concerning the detecting means (in general G01R or other subclasses of G01; reed switches H01H71/2445) · CPC title

• H02H3/08

  responsive to excess current (responsive to abnormal temperature caused by excess current H02H5/04) · CPC title

• H02H7/226 Primary

  for wires or cables, e.g. heating wires · CPC title

• H02H3/0935 Primary

  the timing being determined by numerical means · CPC title

• H03K21/38 Primary

  Starting, stopping or resetting the counter (counters with a base other than a power of two H03K23/48, H03K23/66) · CPC title