TWI475803B - Filter circuit for a connector - Google Patents

Description

Filter circuit applied to the connector

The present invention relates to a filter circuit applied to a connector, and more particularly to a filter circuit having a transformer and a common mode choke connected to each other.

The Taiwan Patent of M396531, published on January 11, 2011, discloses the filter circuit which is provided with a cable side and a physical side which are mutually input and output, and a transformer connected between the two sides. a common mode choke coil, a grounding point, a surge suppression component having a certain on-voltage, and a conductive branch (including a series of resistors and capacitors) connected in parallel with the surge suppression component, the transformer including the primary coil and the pair a first coil and a second coil of the edge coil, the first coil is provided with a center tap and two first connection ends connected to the cable side, and the second coil is provided with two second connection ends connected to the common mode choke coil The mode choke coil includes a third coil and a fourth coil, the third coil is connected between a second connection end and the physical side, and the fourth coil is connected between the other second connection end and the physical side, the surge suppression component The conductive branch is connected in parallel with the center tap of the first coil and the ground point, and the surge suppressing element functions to introduce an overvoltage generated by a surge or a lightning strike into the grounding point.

In practical applications, the grounding point not only absorbs the noise current, but because the grounding point is not an absolute zero potential point, it will have a non-constant and relatively weak potential value, and thus will generate a feedback current to the connected circuit, ie, The grounding point will cause noise interference to the connected circuit. In the prior art, due to the presence of the conductive branch in parallel with the surge suppression component, the grounding point can pass through the conductive branch regardless of whether the surge suppression component is energized or not. It is in communication with the center tap, so that the grounding point outputs a noise current to the center tap through the conductive branch, which affects the performance of the circuit.

The technical problem to be solved by the present invention is to provide a filter circuit applied to a connector, which improves performance by suppressing a grounding point from inputting a noise current to a circuit through a center tap.

In order to solve the above technical problem, the present invention provides a filter circuit applied to a connector having a cable side and a physical side which are input and output of each other, and includes a transformer and a common mode choke connected between the two sides, a grounding point, and a surge suppression component having a certain on-voltage, the transformer includes a first coil and a second coil coupled to each other, the first coil is provided with a center tap and two first connection ends connected to the cable side, and the second coil a second connection end connected to the common mode choke coil, the common mode choke coil includes a third coil and a fourth coil, the third coil is connected between a second connection end and the physical side, and the fourth coil is connected to Between the other second connection end and the physical side, the surge suppression component includes a first end corresponding to the center tap of the first coil and a second end corresponding to the ground point, and the two ends of the surge suppression element When the voltage between the two reaches the turn-on voltage and the surge suppressing element is energized, the center tap of the first coil is electrically connected to the ground point through the surge suppressing element, and the voltage between the two ends of the surge suppressing element is not reached. Thus the ON voltage surge suppression element is not turned on excitation, the center tap and ground of the first coil is disconnected.

For the present invention, when the voltage between the two ends of the surge suppression element reaches the conduction voltage and the surge suppression element is energized, the center tap of the first coil is electrically connected to the ground point through the surge suppression element, when the surge When the voltage between the two ends of the suppression element does not reach the conduction voltage and the surge suppression element is not excited to be turned on, the center tap of the first coil is disconnected from the ground point, and the surge suppression element controls the center tap and the ground point When the circuit encounters an overvoltage generated by a surge or a lightning strike, the overvoltage excites the surge suppression component to be turned on to be further introduced into the grounding point. The surge or lightning strike is a short-lived and accidental event after all. Under normal conditions, the surge suppression component does not encounter the overvoltage generated by the surge or lightning strike, but is in a non-conducting state, so that the grounding point is disconnected from the center tap, and the weak potential of the grounding point cannot form a noise to the center tap. Current, the design of this circuit effectively suppresses the grounding point through the center tap to input noise current to the circuit, and the circuit performance is improved.

The present invention will be further described below in conjunction with the drawings and embodiments.

Referring to the first embodiment, the filter circuit 1 according to the first embodiment of the present invention is applied to a connector (not shown) having cable side 100 and physical side which are input and output of each other. 101. A transformer 11 and a common mode choke 12 connected to the two sides, a grounding point 13, and a surge suppressing element 14 having a constant on-voltage. The transformer 11 includes a first coil 110 and a second coil 111 coupled to each other. The first coil 110 is provided with a center tap 113 and two first connecting ends 112 connected to the cable side 100. The second coil 111 is provided with two second connecting ends 114 connected to the common mode choke coil 12 and a center tap 115. The common mode choke coil 12 includes a third coil 120, a fourth coil 121, and a fifth coil 122 connected to the center tap 115 of the second coil 111. The common mode choke coil 12 is three-wire type, of course, it can also be two. The line type, that is, the fifth coil 122 is not provided. The third coil 120 is connected between the second connection end 114 and the physical side 101, and the fourth coil 121 is connected between the other second connection end 114 and the physical side 101. The surge suppressing element 14 includes a first end 140 corresponding to the center tap 113 of the first coil 110 and a second end 141 corresponding to the ground point 13 when the voltage between the two ends of the surge suppressing element 14 is turned on. When the voltage and thus the surge suppressing element 14 are energized, the center tap 113 of the first coil 110 is electrically connected to the ground point 13 via the surge suppressing element 14, and the voltage between the two ends of the surge suppressing element 14 is not turned on. When the voltage and thus the surge suppression element 14 are not energized, the center tap 113 of the first coil 110 is disconnected from the ground point 13. The surge suppression element 14 controls the conduction and disconnection between the center tap 113 and the ground point 13. The surge suppressing element 14 functions to introduce an overvoltage generated by a surge or a lightning strike into the grounding point 13. In the present embodiment, the surge suppressing element 14 is a thyristor or a gas discharge tube, but is not limited to the above two. The on-voltage of the surge suppression element 14 is 300V, that is, the voltage between the two ends of the surge suppression element 14 reaches (ie, is equal to or greater than) 300V, the surge suppression element 14 is excited to be turned on, and the surge suppression element 14 is The voltage between the terminals does not reach (ie, is less than) 300 V, and the surge suppression element 14 is not energized to be turned off. Of course, the on-voltage of the present surge suppression element 14 is obviously not limited to 300V, and the surge suppression element 14 whose on-voltage is other values may be selected according to actual needs. The center tap 113 of the first coil 110 is directly connected to the surge suppressing element 14 and further connected to the grounding point 13, that is, no other electronic components are connected between the center tap 113 of the first coil 110 and the surge suppressing element 14. . The fifth coil 122 has two connecting ends (not labeled), one connecting end of the fifth coil 122 is connected to the center tap 115 of the second coil 111, and the other connecting end of the fifth coil 122 is connected to a capacitor 15 and grounded. In the embodiment, the other connection end of the fifth coil 122 is directly connected to the capacitor 15 and grounded. Of course, the other connection end of the fifth coil 122 can also be connected to other electronic components (such as a resistor), and then further connected to the capacitor 15 Grounding, that is, the other connection end of the fifth coil 122 can be indirectly connected to the capacitor 15 and grounded. Within the connector, the center tap 113 communicates to the ground point 13 necessarily through the surge suppression element 14, i.e., within the connector, the conductive line that connects the center tap 113 to the ground point 13 necessarily passes through the surge suppression element 14.

Referring to the second figure, in the filter circuit 2 according to the second embodiment of the present invention, only the surge suppressing element 23 and the resistor 22 are connected between the grounding point 24 and the center tap 210 of the first coil 21 of the transformer, and The center tap 210 of the first coil 21, the resistor 22, the surge suppressing element 23, and the grounding point 24 are sequentially connected, and the filter circuit 1 can also be designed as such.

In summary, this creation has indeed met the requirements of the invention patent, and filed a patent application according to law. However, the above description is only a preferred embodiment of the present invention, and the scope of the present invention is not limited to the above-described embodiments, and those who are familiar with the skill of the present invention are equivalent to the equivalent modifications or changes made by the spirit of the present creation. It should be within the scope of the following patent application.

1, 2. . . Filter circuit

100. . . Cable side

101. . . Physical side

11. . . transformer

110, 21. . . First coil

111. . . Second coil

112. . . First connection

113, 115, 210. . . Center tap

114. . . Second connection

12. . . Common mode choke

120. . . Third coil

121. . . Fourth coil

122. . . Fifth coil

13, 24. . . Grounding point

14,23. . . Surge suppression component

140. . . First end

141. . . Second end

15. . . capacitance

twenty two. . . resistance

The first figure is a circuit diagram of a filter circuit in accordance with the first embodiment of the present creation.

The second drawing is a circuit diagram of the filter circuit in accordance with the second embodiment of the present creation.

1. . . Filter circuit

100. . . Cable side

101. . . Physical side

11. . . transformer

110. . . First coil

111. . . Second coil

112. . . First connection

113, 115. . . Center tap

114. . . Second connection

12. . . Common mode choke

120. . . Third coil

121. . . Fourth coil

122. . . Fifth coil

13. . . Grounding point

14. . . Surge suppression component

140. . . First end

141. . . Second end

15. . . capacitance

Claims (7)

A filter circuit applied to a connector has a cable side and a physical side which are input and output of each other, and the filter circuit includes:
a transformer, the transformer includes a first coil and a second coil coupled to each other, the first coil is provided with a center tap and two first connecting ends connected to the cable side, and the second coil is provided with two second connecting ends;
a common mode choke coil, the common mode choke coil includes a third coil and a fourth coil, the third coil is connected between a second connection end and the physical side, and the fourth coil is connected to the other second connection end and the physical side between;
a grounding point; and a surge suppression component having a certain on-voltage; the surge suppression component includes a first end corresponding to the center tap of the first coil and a second end corresponding to the ground point;
Wherein, when the voltage between the two ends of the surge suppressing element reaches the turn-on voltage and the surge suppressing element is energized, the center tap of the first coil is electrically connected to the ground point through the surge suppressing element, and the surge suppressing element is When the voltage between the two ends does not reach the on-voltage and the surge suppressing element is not energized, the center tap of the first coil is disconnected from the ground. The filter circuit of claim 1, wherein the surge suppression element is a thyristor or a gas discharge tube. The filter circuit of claim 1, wherein the center tap of the first coil is directly connected to the surge suppressing element and grounded. The filter circuit of claim 1, wherein the grounding point and the center tap of the first coil are only connected with a surge suppressing element and a resistor, and the center tap of the first coil, the resistor, and the surge suppressing element And the grounding point is connected in turn. The filter circuit of claim 1, wherein the second coil is further provided with a center tap, and the common mode choke coil further comprises a fifth coil connected to the center tap of the second coil. The filter circuit of claim 5, wherein the fifth coil has two connection ends, one connection end of the fifth coil is connected to the center tap of the second coil, and the other connection end of the fifth coil is connected to a capacitor Ground. The filter circuit of claim 1, wherein in the connector, the center tap is connected to the ground point and must pass through the surge suppression element.