CN111929605A - Selectable load resistance value circuit, connecting circuit and multifunctional loader using same - Google Patents

Abstract

The invention discloses an optional load resistance circuit, a connection circuit and a multifunctional load device applying the same, belonging to the power adapter industry. The optional load resistance circuit comprises a plurality of first resistors connected in series, and adjacent first resistors A connecting head is arranged between the two connecting heads; after any two connecting heads are connected with the external circuit, the first resistance between the two connecting heads is connected to the external circuit; the resistance value of the load device connected to the test circuit is adjusted by selecting different connecting heads; Compared with the prior art, the problem of cumbersome resistance configuration during testing is overcome; at the same time, the conventional load is only a simple resistance or sliding resistance load, and the actual power supply product application has a capacitive load; the present invention sets the positive and negative electrodes on the positive and negative electrodes of the PCB respectively. On the other hand, make it self-integrate an equivalent capacitor. In addition to the self-integrated capacitor, a plug-in capacitor is also reserved, and different capacities can be adjusted as needed; the influence of the capacitive load on the EMI test is eliminated; the test results are closer to the product True value at work.

Description

Optional load resistance circuit, connection circuit and multi-function load device applying the same

technical field

The invention belongs to the field of electronic components, in particular to an optional load resistance circuit, a connection circuit and a multifunctional load device applying the same.

Background technique

Resistive loads are often used to test the EMI value of the power supply during the power supply certification test; there are two existing loads, one is a single resistor. When testing power supplies with different voltages and currents, multiple resistors with different resistance values and powers need to be configured. It is very troublesome; there is also a sliding rheostat that can adjust the resistance relatively simply, but it has obvious shortcomings, that is, when the resistance is relatively small, the power cannot be increased, and when the resistance is too small, the resistance will heat up. Seriously, there are obvious limitations of usage scenarios; it is very troublesome and difficult to connect different connectors when loaded at the same time.

In addition, the existing sliding resistors are all circular inductive resistors, which can only simulate the EMI value of the power supply product when the test load is an inductive resistor; and the actual product includes not only inductive resistors, but also non-inductive resistors, capacitors Therefore, it often causes the power supply EMI test to pass, but it fails when it is actually used with electronic equipment.

SUMMARY OF THE INVENTION

Aiming at the shortcomings of the above technologies, the present invention provides a multifunctional load device, which can directly adjust the resistance value of the load device connected to the test circuit through the switch and meet the load requirements of the actual product voltage and current, thereby overcoming the existing technology. The configuration of the middle resistance is troublesome, and the sliding power cannot be increased.

In order to achieve the above purpose, the present invention provides an optional load resistance circuit, which includes a plurality of first resistors connected in series, and a plurality of first resistors connected in series form a resistor string; The end is provided with a connecting head; after any two connecting heads are connected with the external circuit, the first resistance between the two connecting heads is connected to the external circuit.

In a preferred solution, both ends of at least one first resistor are connected in parallel with a short-circuit switch.

In a preferred solution, at least one first resistor is connected in parallel with a second resistor.

In order to achieve the above purpose, the present invention also provides a connection circuit, including an input end and an output end; the input end includes an alligator clip, and the alligator clip is used to clamp the connecting head of the optional load resistance circuit for electrical connection; the output The terminal is used for electrical connection with an external power supply.

In a specific solution, the input end includes one or more of a DC head, an AC head, a wire clamp and an alligator clip.

In a preferred solution, the output terminal includes a positive contact and a negative contact, and the positive contact and the negative contact are respectively used to be arranged on the front and back of the PCB board; after the output terminal is connected to the external power supply, the positive contact and the negative contact are connected to each other. An equivalent capacitor connected in parallel between the two ends of the external power supply is self-integrated.

A preferred solution further includes a plug-in capacitor, which is connected to both ends of the equivalent capacitor in parallel.

The preferred solution further includes a display circuit, which includes a plurality of voltage indicator lights; the indicator lights are used to display the voltage of the power supply and the voltage after being loaded, so as to facilitate the judgment of the working state of the power supply.

In order to achieve the above purpose, the present invention also provides a multifunctional load device, which includes the optional load resistance circuit and a base plate, wherein the first resistor is connected in series through wires and is arranged on the base plate; the base plate is a PCB board or a heat sink. The first resistor is arranged on the PCB board or the heat sink; or the bottom plate includes the heat sink and the PCB board, the first resistor is fixed on the heat sink, and then the first resistor and the heat sink are fixed on the PCB board.

A specific solution further includes the connection circuit, and the connection circuit is arranged on the bottom plate.

The beneficial effects of the invention are:

1. The multifunctional load device provided by the present invention includes an optional load resistance circuit and a base plate; the optional load resistance circuit is arranged on the base plate; the circuit includes an input connection end, an output connection end, and a plurality of input connection ends connected in series. , the first resistor between the output connection terminals, and at least one first resistor is connected in parallel with a short-circuit switch at both ends; the resistance value and the maximum power value of the load connected to the test circuit can be adjusted directly through the switch to overcome the small resistance value of the sliding varistor power. When the power can not do big problem.

2. Or the circuit includes a plurality of first resistors connected in series, and a connector is provided between adjacent first resistors; after any two connectors are connected to an external circuit, the first resistor between the two connectors is connected to the external circuit. ; Select the resistance value and the maximum power value of the load connected to the test circuit by choosing to connect with different connectors; to overcome the problem that the power cannot be increased when the power of the sliding rheostat has a small resistance value.

Description of drawings

1 is a series circuit diagram of an optional load resistance circuit of the present invention;

Fig. 2 is a circuit diagram of a parallel switch on the basis of Fig. 1;

FIG. 3 is a circuit diagram of a second resistor connected in parallel on the basis of FIG. 2 and a switch is set;

Figure 4 is a structural diagram of an optional load resistance circuit arranged on a heat sink;

Figure 5 is a structural diagram of the optional load resistance circuit set on the PCB board;

Fig. 6 is the structure diagram that the bottom plate is a heat sink and a PCB board;

Figure 7 is a diagram of electrical connection between alligator clips for connecting circuits and other circuits;

Fig. 8 is the circuit diagram when the capacitor is connected in parallel on the PCB;

Fig. 9 is the circuit diagram of different voltage indicator lights in the display circuit;

10 is a combination diagram of a power supply detection circuit and a multifunctional load device of the present invention;

Figure 11 shows the relationship between EMI and frequency tested when a 5V, 2A charger is actually working;

Figure 12 shows the relationship between EMI and frequency tested after a 5V, 2A charger is directly connected in series with multiple resistors;

13 is a graph showing the relationship between EMI and frequency tested when a 5V, 2A charger is connected to the multifunctional load device of the present invention.

FIG. 14 is a front structural view of the PCB board of the present invention.

FIG. 15 is a structural diagram of the reverse side of the PCB board of the present invention.

The main component symbols are explained as follows:

1. Alligator clip; 2. Heat sink.

Detailed ways

In order to express the present invention more clearly, the present invention will be further described below with reference to the accompanying drawings.

As mentioned in the background art, the existing single resistor is very troublesome for different voltages, currents and powers, and needs to be configured with many, many resistors with different resistance values and powers; sliding rheostats can overcome the trouble of configuring resistors with different resistance values, and adjust the resistance value relatively simply , but when the resistance value is relatively small, the power cannot be increased.

Based on this, the present invention provides a multifunctional load device, referring to FIGS. 4 to 6 , which includes an optional load resistance circuit and a base plate; the optional load resistance circuit is arranged on the base plate; the optional load resistance circuit itself It includes a number of different optional resistance values and a number of different adjustable powers; it can adapt to the requirements of voltage, current and power in the process of different power supply testing, which can not only avoid the trouble of configuring resistors for each test, but also break through the small When the resistance is used, the power cannot be greatly limited.

The power of the sliding resistor is not large because it is considered that the resistance range is large, and it should cover as much as possible, but the wire diameter can only be relatively small: when low voltage and high current are required, a low resistance, high current load is required; sliding resistors The resistance value of the device itself needs to cover the characteristics as much as possible, and the current should not be too large to be obviously inconsistent; our multi-function load device can be easily set between 0.05-1705R according to certain rules and specific conditions, and the accuracy can reach 0.05 R, it can be changed to different accuracy according to the needs, and the power can also choose different heat sinks according to the needs. It can also be used flexibly according to needs, for example, according to 25R*2, 10R*14, 5R*2, a semi-short-circuit test load can be built without a switch, that is, 50R, 100R, 150R, 200R, 250R; see Figure 14 , The basic resistance value of the resistor is specifically set according to the following regulations: 0.05R, 0.1R, 0.2R, 0.3R, 0.5R, 0.75R; other large basic resistance values are expanded or reduced by 10 times or 10 times according to the above resistance values. When it exceeds 100R, the basic resistance value doubles and increases according to the law of 100R/200R/400R/80R0/160R0/3200R, so as to ensure that the sum of all the previous values is cumulatively greater than the latter value; you can Spell out the required resistance value.

The advantage of setting the resistance in this way is that any value with an accuracy of 0.05R can be configured through a simple switch on and off or the selection of the connector; in addition to the basic resistance, the resistance also includes a fixed value, which is used to expand the multi-function Loader's

The R after the above numbers, and the R in Figures 14-15 in the description, are the basic unit of resistance Ω.

The first solution, referring to FIG. 1 , the optional load resistance circuit includes a plurality of first resistors connected in series, and connecting heads are arranged between adjacent first resistors; after any two connecting heads are connected to an external circuit, the connection between the two connecting heads is The first resistor is connected to the external circuit; when the external power supply is connected to different terminals, the resistance between the terminals is selected as the resistance value of the load to be connected to the power supply detection circuit.

For example, the number of resistors between different terminals is N, the resistance value of each resistor is R, and the resistance value of the load access detection circuit is N*R; by changing the connection between the external power supply and different terminals, the resistance value is changed.

For example: the first resistor includes R1, R2.....Rn; between R1 and R2 there is a connector L1, between R2 and R3 there is a connector L2.....Rn-1 and Rn There is a connector Ln-1; when the external power supply is connected to L1 and Ln-1 respectively, the resistors R2, R3... is 10R, and the resistance values of R1, R2,... L0 and the output end Ln; after L0 and Ln are connected to the external circuit, all R1, R2...Rn can be connected to the external circuit.

For a preferred solution, see FIG. 2, on the basis of the previous solution, at least one first resistor is connected to a short-circuit switch at both ends; when the connection between the external power supply and the terminal is determined, it can also be changed by switching the switch on and off. The resistance value of the connected power detection circuit of the load.

For example, both ends of all the first resistors are connected in parallel with short-circuit switches. When the switches are closed, the first resistors connected in parallel with the open ends will be short-circuited; the number of first resistors connected to the detection circuit is N, and the number of closed switches is M. At this time, the resistance value of the load access detection circuit is (N-M)*R; it may be a parallel switch on some of the first resistors, or a parallel switch on all the first resistors.

For example: the series resistors R2, R3...Rn-1 are connected in parallel with switches K2, K3...Kn-1; when the external power supply is connected with L1 and Ln-1 respectively, , R3.....Rn-1 are connected to the external circuit; by closing the switch K2, that is, R2 is short-circuited, at this time, the resistances connected to the external circuit are R3, R4.....Rn-1; when the power supply process is detected The resistance load value that needs to be configured is 5R, and the resistance values of R1, R2... ...K5 will do.

For a preferred solution, see Fig. 3, at least one resistor is connected in parallel with a second resistor; by connecting the second resistor in parallel, the resistance value can be reduced and the power of the load can be increased; part of the first resistor can be connected in parallel with the second resistor, or all of the second resistor can be connected in parallel. The first resistors are all connected in parallel with the second resistors.

For example: the second resistor includes R1A, R2A...RnA; and the resistance values of R1A, R2A...RnA are all R, and they are all connected in parallel with the first resistors R1...Rn At this time, the power of the load is doubled.

In a preferred solution, one end of the second resistor is directly connected to one end of the first resistor; the other end is connected to the second resistor through a switch; when the switch is closed, it is equivalent to a parallel connection between the first resistor and the second resistor; when the switch is disconnected Then it is equivalent to only the first resistor is valid; the power value of the load is selected by controlling the on-off of the switch between the first resistor and the second resistor; a switch may be provided between part of the first resistor and the second resistor; or All the first resistors and the second resistors are provided with switches.

For example: there is switch K1A between R1 and R1A, switch K2A between R2 and R2A... There is switch KnA between Rn and RnA, by disconnecting switch K2A., R2 and R2A can be disconnected The parallel relationship between them, thereby changing the power of the entire circuit.

In the second solution, the optional load resistance circuit includes an input connection end, an output connection end, and a plurality of first resistors connected in series between the input connection end and the output connection end, and at least one first resistor is connected in parallel with a short-circuit switch at both ends; the input The connection end and the output connection end are respectively connected to the external power supply test circuit; the resistance value and the maximum power value of the load connected to the test circuit can be adjusted directly through the switch, and the power cannot be increased when the small resistance value of the sliding rheostat is overcome. Problem: The difference between this solution and the first solution is that there is no need to set connectors between the first resistors, but the entire circuit is directly connected to the external circuit, and then the resistance and power values are regulated by switches.

Other forms related to the setting of the optimized switch and the setting of the second resistor in this solution are the same as those of the optimized solution of the first solution; they will not be repeated here.

In this embodiment, the first resistor and the second resistor are any one or more of an inductive resistor, a non-inductive resistor, a varistor and a thermistor, but are not limited thereto.

In this embodiment, refer to 4-FIG. 5; the bottom plate is a PCB board or a heat sink 2; when the bottom plate is a heat sink 2, a plurality of first resistors are connected in series and fixed on a heat sink 2 to maximize utilization heat dissipation; when the bottom plate is a PCB board, a plurality of first resistors are connected in series and then fixed on the PCB.

For the preferred solution, see 6, Figure 14 and Figure 15, the bottom plate includes a heat sink 2 and a PCB board; the first resistor is fixed on the heat sink 2, and then the first resistor and the heat sink 2 are fixed on the PCB board; the heat sink 2 Connecting to dissipate heat from the resistor increases the maximum power of the optional load resistance circuit to some extent.

Referring to FIG. 10 , a power detection circuit includes a multi-function load device and a connection circuit; the connection circuit is used to electrically connect an external power supply and an optional load resistance circuit.

The connection circuit includes an input end and an output end; the input end includes an alligator clip 1, and the alligator clip 1 is used for clamping the connecting head of the optional load resistance circuit; the output end is used for electrical connection with an external power supply.

In a specific solution, the input end includes one or more of a DC head, an AC head, a cable holder and an alligator clip 1; but is not limited to this, for example, includes a USB interface or a type-c interface or a DC power interface with different diameters ; The external power supply can be electrically connected to the connection circuit through the alligator clip 1 or a USB interface, a type-c interface or a DC power interface.

Referring to FIG. 9, the preferred solution also includes a display circuit, the display circuit is electrically connected to the connection circuit, and the display circuit indicates the voltage value of the external power supply; the display circuit includes a plurality of voltage indicator lights LED1, LED2...LED8; Different voltage values 100V, 80V, 60V, 48V, 36V, 20V, 12V and 5V.

In a preferred solution, the output end of the connection circuit includes a positive electrode contact and a negative electrode contact, and the positive electrode contact and the negative electrode contact are respectively arranged on the front and back of the PCB board; after the output end is connected to the external power supply, the positive electrode contact and the negative electrode contact An equivalent capacitor EC1 connected to both ends of the external power supply is self-integrated between the points.

In the prior art, the EMI value of the power supply is tested by purely resistive load; while the actual power supply product must include capacitive load in addition to the resistive load; the capacitive load has a certain influence on the EMI of the power supply circuit, if During the test, ignoring the capacitive load will lead to a large difference between the EMI value obtained during the test and the EMI value during the actual operation of the product, which may be qualified during the test but unqualified during use; in order to eliminate this effect, the present invention will The positive contact and negative contact of the connection circuit are used to be set on the front and back of the PCB board respectively; after the output terminal is connected to the external power supply, the positive contact and the negative contact are self-integrated and connected to both ends of the external power supply. Capacitor EC1; put the actual capacitive load of the product on both sides of the resistive load during the test; eliminate the influence of the capacitive load on the EMI test that is not considered; make the test result closer to the real value of the product when it is working.

In this embodiment, the value of the equivalent capacitance EC1 satisfies the formula: (C=S*ε)/d; where C is the numerical value of the equivalent capacitance EC1; S is the relative area of the two conductive layers on the back and front of the PCB board ;ε is the dielectric constant of the PCB board; d is the thickness of the PCB board; when connecting the circuit with different connectors, the value of the equivalent capacitance EC1 will not change; that is, when changing the resistive load value, the capacitive Load values are not affected; resistive and capacitive loads are independent of each other.

In this implementation, one or more equivalent capacitors EC1C may be additionally connected to the connection circuit; both ends of the equivalent capacitor EC1C are respectively connected to a pair of contacts of the connection circuit; thus, the equivalent capacitors EC1C are connected in parallel with Both ends of the equivalent capacitor EC1; the quantity and capacitance value of the equivalent capacitor EC1C can be selected according to the test needs; a part of the equivalent capacitor EC1C can also be connected between the contacts in advance, and a switch is connected in series between the capacitor and the contacts; Whether the capacitor is connected in parallel with the equivalent capacitor EC1 is controlled by switching on and off.

In this embodiment, the size of the PCB board is: 302mm*148mm; the thickness is 1-1.6cm; the connection circuit is arranged on the front side of the PCB; the connector is connected to the back side of the PCB board;

Refer to Figure 11-Figure 13; Figure 11 is the relationship between EMI and frequency tested when the 5V, 2A charger is actually working; Figure 12 is the EMI tested after the 5V, 2A charger is directly connected in series with multiple resistors The relationship between frequency and frequency; Figure 13 is the relationship between EMI and frequency tested when the 5V, 2A charger is connected to the multi-function load in this example; the load resistance value is 2.5R; it can be known from the figure: When the resistance load is directly connected in series, the margin reaches 8dBuV, but the actual result of the mobile phone test not only has no margin, but also lacks more than 3 dBuV. The test waveform of our multi-function load device is closer to the actual charging effect of the mobile phone. The test result is Exceeding 4dBuV, the test structure is closer to the real value when the product is actually used.

The advantages of the present invention are:

1. Multi-function load device, including optional load resistance circuit and base plate; optional load resistance circuit is set on the base plate; optional load resistance circuit itself includes multiple different optional resistance values and multiple different adjustable resistance values. Power; it can adapt to the requirements of voltage, current and power in the process of different power supply testing, which can not only avoid the trouble of configuring resistors for each test, but also can break through the small resistance, the power cannot be greatly limited.

2. The resistance value of the load connected to the detection circuit can be selected by controlling the on-off of the switch in parallel with the first resistance.

3. The power value and resistance value of the load can be selected by controlling the on-off of the switch between the first resistor and the second resistor.

The above disclosures are only a few specific embodiments of the present invention, but the present invention is not limited thereto, and any changes that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims (10)

1. An optional load resistance circuit, characterized in that it comprises a plurality of first resistors connected in series, and a plurality of first resistors connected in series form a resistor string; There are connecting heads; after any two connecting heads are connected to the external circuit, all the first resistors between the two connecting heads are connected to the external circuit. 2 . The selectable load resistance circuit according to claim 1 , wherein at least one first resistor is connected in parallel with a short-circuit switch at both ends. 3 . 3 . The optional load resistance circuit according to claim 1 , wherein a second resistor is connected in parallel with at least one of the first resistors. 4 . 4. A connection circuit, characterized in that it comprises an input end and an output end; the input end is used for electrical connection with the connector of the optional load resistance circuit described in claim 1; the output end is used for electrical connection with an external power supply. connect. 5 . The connection circuit according to claim 4 , wherein the input terminal or the output terminal comprises one or more of a DC head, an AC head, a wire clip holder and an alligator clip. 6 . 6. The connection circuit according to claim 4, wherein the output terminal comprises a positive contact and a negative contact, and the positive contact and the negative contact are respectively used to be arranged on the front and back of the PCB board; the output is connected to the external After the power supply is connected, an equivalent capacitor connected to both ends of the external power supply is self-integrated between the positive contact and the negative contact. 7 . The connection circuit according to claim 6 , further comprising a plug-in capacitor, the plug-in capacitor being connected to both ends of the equivalent capacitor in parallel. 8 . 8 . The connection circuit according to claim 6 , further comprising a display circuit, the display circuit comprising a plurality of voltage indicator lights; the voltage indicator lights are used to display the power supply voltage and the voltage after being loaded. 9 . 9. A multifunctional load device, characterized in that it comprises a base plate and the optional load resistance circuit according to any one of claims 1-3, wherein the first resistor is arranged on the base plate after being connected in series; the base plate is a PCB board Or the heat sink; the first resistor is arranged on the PCB board or the heat sink; or the bottom plate includes the heat sink and the PCB board, the first resistor is fixed on the heat sink, and then the first resistor and the heat sink are fixed on the PCB board. 10 . The multifunctional load device according to claim 9 , further comprising the connection circuit according to any one of claims 4 to 8 , wherein the connection circuit is arranged on the base plate. 11 .

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