Foreign object detection method and power supply terminal with foreign object detection function

Abstract

A foreign object detection method and a power supply terminal with a foreign object detection function. The foreign object detection method is used to detect whether there is a foreign object on a function pin of a power supply terminal or a power receiving terminal, wherein the power supply terminal and the power receiving terminal are coupled to each other in a pluggable manner. The foreign object detection method comprises: discharging a capacitor through a function pin, wherein the capacitor is electrically connected to the function pin; providing a sensing current through the function pin to charge the capacitor; sensing a voltage change of the function pin during a preset period; and comparing the voltage change with the preset change to determine whether there is a foreign object on the function pin.

Description

Technical Field

[0001] The present invention relates to a foreign object detection method and a power supply terminal with a foreign object detection function, and in particular to a foreign object detection method for determining whether a foreign object exists on a function pin according to a voltage change on the function pin and a power supply terminal with a foreign object detection function. Background Art

[0002] Please refer to Figure 1 , which shows a circuit diagram of a power supply system of the prior art. This prior art discharges pin CC2 via resistor Rd by controlling switches SW2 and SW4, and then sets pin CC2 to a floating state by controlling switches SW2 and SW4, and comparator COM2 outputs a comparison result Det_R between the voltage level of pin CC2 and the level of reference voltage Vref. When a foreign object such as moisture exists between pin VBUS and pin CC2 in the power supply terminal, the power supply voltage (such as the voltage 5V provided by pin VBUS) will be provided to pin CC2 through the foreign object such as moisture, so the voltage of pin CC2 will increase. Therefore, when the voltage of pin CC2 is judged by comparator COM2 to be higher than the level of reference voltage Vref, the system will determine that a foreign object such as moisture exists in the power supply terminal; however, this prior art must wait until the voltage of pin CC2 is stable before judging whether it is higher than reference voltage Vref, so it takes a lot of time.

[0003] In view of this, the present invention proposes a foreign object detection method capable of determining whether a foreign object exists on a function pin according to a voltage change on the function pin, and a power supply terminal with a foreign object detection function. Summary of the invention

[0004] From one of the viewpoints, the present invention provides a foreign object detection method for detecting whether there is a foreign object on a function pin of a power supply end or a power receiving end, the power supply end and the power receiving end are coupled to each other in a pluggable manner, the foreign object detection method includes: discharging a capacitor through the function pin, wherein the capacitor is electrically connected to the function pin; providing a sensing current through the function pin to charge the capacitor; sensing a voltage change of the function pin during a preset period; and comparing the voltage change with a preset change to determine whether there is a foreign object on the function pin.

[0005] From another perspective, the present invention also provides a power supply end with a foreign object detection function, the power supply end has the function of detecting whether there is a foreign object on one of the functional pins, and the power supply end is a power supply end or a power receiving end, wherein the power supply end and the power receiving end are coupled to each other in a pluggable manner, and the power supply end is used to supply power to the power receiving end, the power supply end includes: a discharge circuit, including a switch, the switch is electrically connected to the functional pin and a capacitor, the switch is used to discharge the capacitor through the functional pin, wherein the capacitor is electrically connected to the functional pin; a current source circuit, the current source circuit is electrically connected to the functional pin and the capacitor, the current source circuit is used to provide a sensing current flowing through the functional pin to charge the capacitor; and a foreign object detection circuit, which is used to sense a voltage change of the functional pin during a preset period, and compare the voltage change with a preset change to determine whether there is a foreign object on the functional pin.

[0006] In a preferred embodiment, the predetermined change is determined according to the capacitance value of the capacitor.

[0007] In a preferred embodiment, the power supply end or the power receiving end is a universal serial bus (USB), and the function pins include a VBUS pin, a DP pin, a DM pin, a CC1 pin, a CC2 pin, an SBU1 pin or an SBU2 pin of the USB.

[0008] In a preferred embodiment, the step of sensing a voltage change of the function pin during a preset period includes: at a starting time point of the preset period, sensing an initial voltage of the function pin, wherein the starting time point is after the step of discharging the capacitor through the function pin and before the step of providing the sensing current through the function pin to charge the capacitor; at a preset time point of the preset period, sensing a period voltage of the function pin; and at an end time point of the preset period, sensing an end voltage of the function pin, wherein the end time point is after the preset time point.

[0009] In a preferred embodiment, the voltage change includes a first voltage change and a second voltage change; wherein the first voltage change is the difference between the end voltage and the initial voltage, and the second voltage change is the difference between the end voltage and the period voltage.

[0010] In a preferred embodiment, the step of sensing a voltage change of the function pin during a preset period further includes: discharging the capacitor through the function pin after sensing the end voltage of the function pin at the end point of the preset period.

[0011] In a preferred embodiment, the step of comparing the voltage change with a preset change to determine whether there is a foreign object on the function pin includes: comparing the first voltage change with a first preset change of the preset change; when the first voltage change is not greater than the first preset change, comparing the second voltage change with a second preset change of the preset change; and when the second voltage change is not greater than the second preset change, determining that there is a foreign object on the function pin.

[0012] In a preferred embodiment, the period from the start time point to the end time point does not exceed 100 milliseconds.

[0013] In a preferred embodiment, the switch includes a high voltage metal oxide semiconductor (MOS) device or a low voltage MOS device.

[0014] In a preferred embodiment, the foreign object detection circuit includes an analog-to-digital converter or a comparator.

[0015] The advantage of the present invention is that the present invention does not need to wait for the voltage on the function pin to reach a stable state, so the present invention can detect whether a foreign object exists on the function pin within a predetermined time.

[0016] The following detailed description through specific embodiments will make it easier to understand the purpose, technical content, characteristics and effects achieved by the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a circuit diagram showing a power supply system of the prior art.

[0018] Figure 2 FIG. 4 is a block diagram showing a power supply terminal with a foreign object detection function according to an embodiment of the present invention.

[0019] Figure 3 FIG. 4 is a schematic diagram showing a signal waveform of a power supply terminal having a foreign object detection function according to an embodiment of the present invention.

[0020] Figure 4 The graph is a graph showing a first voltage change corresponding to a capacitance value of a function pin of a power supply terminal having a foreign object detection function according to an embodiment of the present invention.

[0021] Figure 5 The graph is a graph showing the second voltage variation of the function pin of the power supply terminal with the foreign object detection function corresponding to the capacitance value according to an embodiment of the present invention.

[0022] Figure 6-Figure 9 is a flow chart showing the steps of a foreign object detection method according to an embodiment of the present invention.

[0023] Explanation of symbols in the figure

[0024] 20: Power supply terminal with foreign object detection function

[0025] 30: Foreign body detection method

[0026] 201: Function pin

[0027] 202: Discharge circuit

[0028] 203: Current Source Circuit

[0029] 204: Foreign object detection circuit

[0030] 301~304,3031~3034,3041~3043:Steps

[0031] Cfp: Capacitance

[0032] COM2: Comparator

[0033] Det_R: Comparison results

[0034] Id: sensing current

[0035] Rd, Rp: resistance

[0036] Rfod: resistance value of foreign matter

[0037] SW2, SW4: Switch

[0038] t0: starting time

[0039] t1: preset time point

[0040] t2: End point

[0041] VBUS, CC2: Pins

[0042] Vfp: voltage

[0043] Vfp_t0: initial voltage

[0044] Vfp_t1: voltage during

[0045] Vfp_t2: End voltage

[0046] Vref: reference voltage

[0047] ΔVfp1: First voltage change

[0048] ΔVfp2: Second voltage change

[0049] ΔVth1: First preset change

[0050] ΔVth2: Second preset change DETAILED DESCRIPTION

[0051] The drawings in the present invention are all schematic, and are mainly intended to show the coupling relationship between various circuits and the relationship between various signal waveforms. The circuits, signal waveforms and frequencies are not drawn according to scale.

[0052] Figure 2 FIG. 1 is a block diagram showing a power supply terminal with a foreign object detection function according to an embodiment of the present invention. Figure 2 The power supply terminal 20 with a foreign object detection function of the present invention has a function of detecting whether there is a foreign object on one of the functional pins 201. In one embodiment, the power supply terminal 20 with a foreign object detection function is, for example, a power supply terminal or a power receiving terminal. The power supply terminal and the power receiving terminal are coupled to each other in a pluggable manner, and the power supply terminal is used to supply power to the power receiving terminal. In one embodiment, the power supply terminal or the power receiving terminal is, for example, a universal serial bus (USB).

[0053] like Figure 2 As shown, the power supply terminal 20 with foreign object detection function of the present invention includes a discharge circuit 202, a current source circuit 203 and a foreign object detection circuit 204. In one embodiment, the discharge circuit 202 includes a switch, and the switch is coupled to the ground potential. In one embodiment, the switch is, for example but not limited to, a high-voltage metal oxide semiconductor (MOS) element or a low-voltage MOS element. The discharge circuit 202, such as a switch, is electrically connected to the function pin 201 and the capacitor Cfp, and the capacitor Cfp is electrically connected to the function pin 201. The discharge circuit 202, such as a switch, is used to discharge the capacitor Cfp through the function pin 201.

[0054] The current source circuit 203 is electrically connected to the function pin 201 and the capacitor Cfp, and the current source circuit 203 is used to provide a sensing current Id flowing through the function pin 201 to charge the capacitor Cfp. In one embodiment, the current source circuit 203 is, for example, but not limited to, a low voltage dropout regulator. The foreign object detection circuit 204 is coupled to the function pin 201, and is used to sense the change of the voltage Vfp of the function pin 201 during a preset period, and compare the voltage change with the preset change to determine whether there is a foreign object on the function pin 201. In one embodiment, the foreign object detection circuit 204 is, for example, but not limited to, an analog-to-digital converter (ADC) or a comparator.

[0055] In one embodiment, the preset change is determined according to the capacitance of the capacitor Cfp. In one embodiment, the function pin 201 includes a VBUS pin, a DP pin, a DM pin, a CC1 pin, a CC2 pin, a SBU1 pin or a SBU2 pin of a USB.

[0056] Figure 3 is a schematic diagram showing a signal waveform of a power supply terminal having a foreign object detection function according to an embodiment of the present invention. Figure 2 and Figure 3 , the foreign object detection circuit 204 senses the change of the voltage Vfp of the function pin 201 during the preset period by the following steps: First, at the starting time point t0 of the preset period, the initial voltage Vfp_t0 of the function pin 201 is sensed, wherein the starting time point t0 is after the step of discharging the capacitor Cfp through the function pin 201 and before the step of providing the sensing current Id through the function pin 201 to charge the capacitor Cfp. Next, at the preset time point t1 of the preset period, the period voltage Vfp_t1 of the function pin 201 is sensed. Next, at the ending time point t2 of the preset period, the ending voltage Vfp_t2 of the function pin 201 is sensed, wherein the ending time point t2 is after the preset time point t1.

[0057] like Figure 3 and Figure 2 As shown, the step of sensing the voltage change of the function pin 201 during the preset period by the foreign object detection circuit 204 further includes: after sensing the end voltage Vfp_t2 of the function pin 201 at the end point t2 of the preset period, the capacitor Cfp is discharged through the function pin 201. In one embodiment, the period from the starting time point t0 to the end point t2 is, for example, no more than 100 milliseconds.

[0058] In one embodiment, the voltage variation includes a first voltage variation ΔVfp1 and a second voltage variation ΔVfp2. The first voltage variation ΔVfp1 is the difference between the end voltage Vfp_t2 and the initial voltage Vfp-_t0, and the second voltage variation ΔVfp2 is the difference between the end voltage Vfp_t2 and the period voltage Vfp_t1. Figure 4 1 is a graph showing a first voltage variation ΔVfp1 of a function pin 201 of a power supply terminal 20 with a foreign object detection function corresponding to a capacitance Cfp according to an embodiment of the present invention. Figure 5 1 is a graph showing a second voltage change ΔVfp2 of a function pin 201 of a power supply terminal 20 with a foreign object detection function corresponding to a capacitance Cfp according to an embodiment of the present invention. In one embodiment, Figure 4 The relationship equation between the first voltage change ΔVfp1 and the capacitance Cfp is:

[0059]

[0060] Where Rfod represents the resistance value of the foreign object, t2 represents the end point, and Id represents the sensing current. In one embodiment, Figure 5The relationship equation between the second voltage change ΔVfp2 and the capacitance Cfp is:

[0061]

[0062] Where Rfod represents the resistance value of the foreign body, t1 represents the preset time point, and t2 represents the end time point. Equation (1) and equation (2) can be derived as follows:

[0063]

[0064] Wherein Vfp_t represents the voltage of the function pin 201 at any time point t, Vfp_t0 represents the initial voltage of the function pin 201 at the initial time point t0 (where t=0), Vfp_t1 represents the period voltage of the function pin 201 at the preset time point t1, and Vfp_t2 represents the ending voltage of the function pin 201 at the ending time point t2.

[0065] Please also refer to Figure 3 , Figure 4 and Figure 5 The foreign object detection circuit 204 compares the voltage change with the preset change by the following steps to determine whether there is a foreign object on the function pin 201: First, compare the first voltage change ΔVfp1 with the first preset change ΔVth1 of the preset change. Then, when the first voltage change ΔVfp1 is not greater than the first preset change ΔVth1, compare the second voltage change ΔVfp2 with the second preset change ΔVth2 of the preset change. Then, when the second voltage change ΔVfp2 is not greater than the second preset change ΔVth2, it is determined that there is a foreign object on the function pin 201.

[0066] Figure 6-Figure 9 FIG. 1 is a flowchart showing a method for detecting foreign matter according to an embodiment of the present invention. Figure 6 As shown, the foreign object detection method 30 of the present invention includes, in step 301, discharging the capacitor via the function pin, wherein the capacitor is electrically connected to the function pin. Next, in step 302, providing a sensing current via the function pin to charge the capacitor. Thereafter, in step 303, sensing the voltage change of the function pin during a preset period. Next, in step 304, comparing the voltage change with the preset change to determine whether there is a foreign object on the function pin.

[0067] like Figure 7As shown, in one embodiment, step 303 includes steps 3031, 3032 and 3033. In step 3031, at the start time point of the preset period, the initial voltage of the function pin is sensed, wherein the start time point is after the step of discharging the capacitor through the function pin and before the step of providing the sensing current through the function pin to charge the capacitor. Afterwards, at step 3032, at the preset time point of the preset period, the period voltage of the function pin is sensed. Next, at step 3033, at the end time point of the preset period, the end voltage of the function pin is sensed, wherein the end time point is after the preset time point.

[0068] like Figure 8 As shown, in one embodiment, step 303 may further include step 3034. In step 3034, at the end of the preset period, after the step of sensing the end voltage of the function pin, the capacitor is discharged through the function pin. Fig. 9 As shown, in one embodiment, step 304 includes steps 3041, 3042, and 3043. In step 3041, the first voltage change is compared with a first preset change of the preset change. Then, in step 3042, when the first voltage change is not greater than the first preset change, the second voltage change is compared with a second preset change of the preset change. Thereafter, in step 3043, when the second voltage change is not greater than the second preset change, it is determined that there is a foreign object on the functional pin.

[0069] As described above, the present invention provides a power supply terminal with a foreign object detection function and a foreign object detection method. The present invention detects voltage changes rather than detecting the stable voltage on the function pin. Since the present invention does not need to wait for the voltage on the function pin to reach a stable state, the present invention can detect whether a foreign object exists on the function pin within a predetermined time.

[0070] The present invention has been described above with respect to the preferred embodiment, but the above is only to make it easy for those skilled in the art to understand the content of the present invention, and is not used to limit the scope of rights of the present invention. The various embodiments described are not limited to individual applications, but can also be used in combination. For example, two or more embodiments can be used in combination, and part of the components in one embodiment can also be used to replace the corresponding components in another embodiment. In addition, under the same spirit of the present invention, those skilled in the art can think of various equivalent changes and various combinations. For example, the present invention refers to "processing or calculating or generating an output result according to a certain signal", which is not limited to the signal itself, but also includes, when necessary, converting the signal to voltage and current, current and voltage, and / or ratio conversion, and then processing or calculating according to the converted signal to generate an output result. It can be seen from this that under the same spirit of the present invention, those skilled in the art can think of various equivalent changes and various combinations, and there are many combinations, which are not listed one by one here. Therefore, the scope of the present invention should cover the above and all other equivalent changes.

Claims

1. A foreign object detection method for detecting whether a foreign object exists on a functional pin of a power supply end or a power receiving end, wherein the power supply end and the power receiving end are coupled to each other in a pluggable manner, and the foreign object detection method comprises: discharging a capacitor via the function pin, wherein the capacitor is electrically connected to the function pin; Providing a sensing current through the function pin to charge the capacitor; sensing a voltage change of the functional pin during a preset period; and Comparing the voltage change with a preset change to determine whether there is a foreign object on the functional pin; The step of sensing a voltage change of the functional pin during a preset period includes: At a starting time point of the preset period, sensing an initial voltage of the function pin, wherein the starting time point is after the step of discharging the capacitor through the function pin and before the step of providing the sensing current through the function pin to charge the capacitor; At a preset time point in the preset period, sensing a period voltage of the function pin; and At an end time point of the preset period, sensing an end voltage of the function pin, wherein the end time point is later than the preset time point, and the preset time point is later than the start time point; The voltage change includes a first voltage change and a second voltage change; the first voltage change is the difference between the end voltage and the initial voltage, and the second voltage change is the difference between the end voltage and the period voltage.

2. The foreign body detection method according to claim 1, wherein: The preset change is determined according to the capacitance value of the capacitor.

3. The foreign body detection method according to claim 1, wherein: The power supply end or the power receiving end is a universal serial bus, and the function pins include a VBUS pin, a DP pin, a DM pin, a CC1 pin, a CC2 pin, a SBU1 pin or a SBU2 pin of the universal serial bus.

4. The foreign body detection method according to claim 1, wherein: The step of sensing a voltage change of the functional pin during a preset period further includes: At the end point of the preset period, after the step of sensing the end voltage of the function pin, the capacitor is discharged through the function pin.

5. The foreign body detection method according to claim 1, wherein: The step of comparing the voltage change with a preset change to determine whether there is a foreign object on the functional pin includes: comparing the first voltage variation with a first preset variation of the preset variation; When the first voltage variation is not greater than the first preset variation, comparing the second voltage variation with a second preset variation of the preset variation; and When the second voltage variation is not greater than the second preset variation, it is determined that a foreign object exists on the functional pin.

6. The foreign body detection method according to claim 1, wherein: The period from the start time point to the end time point does not exceed 100 milliseconds.

7. A power supply end with a foreign object detection function, the power supply end has the function of detecting whether there is a foreign object on one of the functional pins, and the power supply end is a power supply end or a power receiving end, wherein the power supply end and the power receiving end are coupled to each other in a pluggable manner, and the power supply end is used to supply power to the power receiving end, and the power supply end comprises: a discharge circuit, comprising a switch, the switch being electrically connected to the function pin and a capacitor, the switch being used to discharge the capacitor via the function pin, wherein the capacitor is electrically connected to the function pin; a current source circuit, the current source circuit being electrically connected to the function pin and the capacitor, the current source circuit being used to provide a sensing current flowing through the function pin to charge the capacitor; and a foreign object detection circuit, for sensing a voltage change of the function pin during a preset period, and comparing the voltage change with a preset change to determine whether a foreign object exists on the function pin; The foreign object detection circuit senses the voltage change of the function pin during the preset period by the following steps: At a starting time point of the preset period, sensing an initial voltage of the function pin, wherein the starting time point is after the step of discharging the capacitor through the function pin and before the step of providing the sensing current through the function pin to charge the capacitor; At a preset time point in the preset period, sensing a period voltage of the function pin; and At an end time point of the preset period, sensing an end voltage of the function pin, wherein the end time point is later than the preset time point, and the preset time point is later than the start time point; The voltage change includes a first voltage change and a second voltage change; the first voltage change is the difference between the end voltage and the initial voltage, and the second voltage change is the difference between the end voltage and the period voltage.

8. The power supply terminal with foreign object detection function as claimed in claim 7, wherein: The preset change is determined according to the capacitance value of the capacitor.

9. The power supply terminal with foreign object detection function as claimed in claim 7, wherein: The power supply end or the power receiving end is a universal serial bus, and the function pins include a VBUS pin, a DP pin, a DM pin, a CC1 pin, a CC2 pin, a SBU1 pin or a SBU2 pin of the universal serial bus.

10. The power supply terminal with foreign object detection function as claimed in claim 7, wherein: The step of sensing the voltage change of the function pin during the preset period by the foreign object detection circuit further includes: At the end point of the preset period, after the step of sensing the end voltage of the function pin, the capacitor is discharged through the function pin.

11. The power supply terminal with foreign object detection function as claimed in claim 7, wherein: The foreign object detection circuit compares the voltage change with the preset change to determine whether there is a foreign object on the functional pin by the following steps: comparing the first voltage variation with a first preset variation of the preset variation; When the first voltage variation is not greater than the first preset variation, comparing the second voltage variation with a second preset variation of the preset variation; and When the second voltage variation is not greater than the second preset variation, it is determined that a foreign object exists on the functional pin.

12. The power supply terminal with foreign object detection function as claimed in claim 7, wherein: The period from the start time point to the end time point does not exceed 100 milliseconds.

13. The power supply terminal with foreign object detection function as claimed in claim 7, wherein: The switch includes a high voltage metal oxide semiconductor element or a low voltage metal oxide semiconductor element.

14. The power supply terminal with foreign object detection function as claimed in claim 7, wherein the foreign object detection circuit comprises an analog-to-digital converter or a comparator.

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