CN111929605A

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

Info

Publication number: CN111929605A
Application number: CN202010942477.7A
Authority: CN
Inventors: 严宗周
Original assignee: Shenzhen Yuanneng Electric Appliance Co ltd
Current assignee: Shenzhen Yuanneng Electric Appliance Co ltd
Priority date: 2020-09-09
Filing date: 2020-09-09
Publication date: 2020-11-13

Abstract

The invention discloses a selectable load resistance circuit, a connecting circuit and a multifunctional loader using the same, belonging to the industry of power adapters, wherein the selectable load resistance circuit comprises a plurality of first resistors which are connected in series, and a connecting head is arranged between the adjacent first resistors; after any two connectors are connected with an external circuit, a first resistor between the two connectors is connected into the external circuit; the resistance value of the load connected into the test circuit is adjusted by selecting different connectors; compared with the prior art, the problem of troublesome resistor configuration during testing is solved; meanwhile, the conventional load is only a simple resistor or a sliding resistor load, and the actual power supply product application has a capacitive load; in the invention, the positive electrode and the negative electrode are respectively arranged on the front side and the back side of the PCB, so that the PCB is self-integrated into an equivalent capacitor, a plug-in capacitor is reserved besides the self-integrated capacitor, and different capacities are adjusted according to requirements; eliminating the influence of capacitive load on EMI test; so that the test result is closer to the true value of the product in operation.

Description

Selectable load resistance value circuit, connecting circuit and multifunctional loader using same

Technical Field

The invention belongs to the field of electronic components, and particularly relates to a circuit capable of selecting a load resistance value, a connecting circuit and a multifunctional loader using the circuit.

Background

When the power supply is tested in an authentication mode, the EMI value of the power supply is tested by using a common resistance load; the existing load has two types, one type is a single resistor, when testing power supplies with different voltages and currents, a plurality of resistors with different resistance values and powers need to be configured, and the configuration is very troublesome; the sliding rheostat can relatively simply adjust the resistance value, but has a relatively obvious short board, namely when the resistance value is relatively small, the power cannot be large, and when the resistance value is too small, the resistance can generate heat seriously, so that obvious use scene limitation exists; and the connection of different joints is very troublesome and difficult when the load is applied.

In addition, the existing sliding resistors are all round inductive resistors, so that the EMI value of a power supply product can only be simulated when the test load is the inductive resistor; the actual product comprises not only an inductive resistor, but also a non-inductive resistor and a capacitive load; therefore, the power supply EMI can pass the test frequently, and the power supply EMI can not pass the test when being actually matched with the electronic equipment for use.

Disclosure of Invention

Aiming at the defects in the prior art, the invention provides the multifunctional loader which can be directly connected into a test circuit through a switch to adjust the resistance value of the loader and meet the load-bearing requirement of voltage and current of an actual product, and solves the problems that the resistor is troublesome to configure and the sliding power cannot be large in the prior art.

In order to achieve the above object, the present invention provides a selectable load resistance circuit, which includes a plurality of first resistors connected in series, wherein the plurality of first resistors connected in series form a resistor string; connectors are arranged at the head end and the tail end of the adjacent first resistor or the resistor string; after any two connectors are connected with an external circuit, a first resistor between the two connectors is connected into the external circuit.

Preferably, the two ends of at least one first resistor are connected with the short-circuit switch in parallel.

Preferably, at least one first resistor is connected in parallel with a second resistor.

In order to achieve the above object, the present invention further provides a connection circuit, including an input terminal and an output terminal; the input end comprises an alligator clip which is used for clamping the connector of the selectable load resistance circuit to be electrically connected; the output end is used for being electrically connected with an external power supply.

In a specific embodiment, the input terminal comprises one or more of a DC head, an AC head, a wire holder and an alligator clip.

In a preferred scheme, the output end comprises a positive contact and a negative contact, and the positive contact and the negative contact are respectively arranged on the front side and the back side of the PCB; after the output end is connected with an external power supply, an equivalent capacitor which is connected in parallel with the two ends of the external power supply is self-integrated between the positive contact and the negative contact.

Preferably, the circuit further comprises a plug-in capacitor, and the plug-in capacitor is connected in parallel with two ends of the equivalent capacitor.

The display circuit comprises a plurality of voltage indicator lamps; the pilot lamp is used for displaying the voltage of the power supply and the voltage after loading, and the working state of the power supply is conveniently judged.

In order to achieve the above object, the present invention further provides a multifunctional load device, including the circuit with selectable load resistance value and a bottom plate, wherein the first resistor is connected in series through a wire and then arranged on the bottom plate; the bottom plate is a PCB or a radiating fin; the first resistor is arranged on the PCB or the heat sink; or the bottom plate comprises a radiating fin and a PCB, the first resistor is fixed on the radiating fin, and then the first resistor and the radiating fin are fixed on the PCB.

The specific scheme also comprises the connecting circuit, and the connecting circuit is arranged on the bottom plate.

The invention has the beneficial effects that:

1. the invention provides a multifunctional loader, which comprises a selectable load resistance value circuit and a bottom plate; the selectable load resistance value circuit is arranged on the bottom plate; the circuit comprises an input connecting end, an output connecting end and a plurality of first resistors which are connected in series between the input connecting end and the output connecting end, wherein two ends of at least one first resistor are connected with a short-circuit switch in parallel; the resistance value and the maximum power value of the load device connected into the test circuit can be directly adjusted through the switch, and the problem that the power cannot be increased when the power of the slide rheostat is small in resistance value is solved.

2. Or the circuit comprises a plurality of first resistors connected in series, and a connector is arranged between the adjacent first resistors; after any two connectors are connected with an external circuit, a first resistor between the two connectors is connected into the external circuit; selecting the resistance value and the maximum power value of the load device connected to the test circuit by selecting different connectors; the problem that the power cannot be increased when the power of the slide rheostat is low in resistance is solved.

Drawings

FIG. 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 circuit based on FIG. 1;

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

FIG. 4 is a diagram of an alternative load resistance circuit disposed on a heat sink;

FIG. 5 is a diagram of a selectable load resistance circuit disposed on a PCB board;

FIG. 6 is a block diagram of the base plate as a heat sink and PCB;

FIG. 7 is an electrical connection diagram of the crocodile clip for connecting the circuit with other circuits;

FIG. 8 is a circuit diagram of a capacitor connected in parallel to a PCB board;

FIG. 9 is a circuit diagram showing different voltage indicator lamps in the circuit;

FIG. 10 is a diagram of a power detection circuit in combination with the multi-functional load of the present invention;

FIG. 11 is a graph of EMI versus frequency for a 5V, 2A charger during actual operation;

FIG. 12 is a graph showing the relationship between EMI and frequency of a 5V, 2A charger directly connected in series with a plurality of resistors;

fig. 13 is a graph of EMI versus frequency for a 5V, 2A charger when connected to a multi-functional load of the present invention.

Fig. 14 is a front view of the PCB of the present invention.

FIG. 15 is a view showing the reverse side of the PCB of the present invention.

The main element symbols are as follows:

1. a crocodile clip; 2. and a heat sink.

Detailed Description

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

As described in the background art, the existing single resistor is very troublesome for different voltages, currents and powers, and needs to be configured with a plurality of resistors with different resistances and powers; the slide rheostat can overcome the trouble of configuring resistors with different resistance values, relatively simply adjusts the resistance value, but when the resistance value is smaller, the power cannot be increased.

In this regard, the present invention provides a multi-functional load device, see fig. 4-6, which includes a selectable load resistance circuit and a bottom plate; the selectable load resistance value circuit is arranged on the bottom plate; the selectable load resistance value circuit comprises a plurality of different selectable resistance values and a plurality of different adjustable powers; the device can adapt to the requirements for voltage, current and power in different power supply detection processes, can avoid the trouble that the resistor needs to be configured in each test, and can break through the small resistor, so that the power cannot be greatly limited.

The power of the sliding resistor is not large because the resistance range is considered to be large, the sliding resistor covers as much as possible, and only the wire diameter is thin, when low voltage is needed and large current is loaded, the low resistance value and the large current are needed; the sliding resistor needs the characteristic that the resistance value covers as much as possible, and the current cannot be too large and obviously not conform to the requirement; the multifunctional loader can be easily arranged between 0.05 and 1705R according to a certain rule and a specific situation and according to the rule, the precision reaches 0.05R, different precisions can be made according to needs, and different cooling fins can be selected according to the power. The method can be flexibly applied according to the requirements, for example, according to 25R × 2, 10R × 14 and 5R × 2, half-short-circuit test loads, namely 50R, 100R, 150R, 200R and 250R can be built without switches; referring to fig. 14, the basic resistance of the resistor is specifically set as follows: 0.05R, 0.1R, 0.2R, 0.3R, 0.5R, 0.75R; other large base resistances are enlarged or reduced by 10 times, or by 10 times, a power exponent, according to the above resistance; when the sum exceeds 100R, according to the rule that the basic resistance value is doubled and the value is increased according to the rule of 100R/200R/400R/80R0/160R0/3200R, the sum of all the values in the front is ensured to be larger than the next value; the desired resistance value can be spelled out.

The advantage of setting the resistance value is that any value with the precision of 0.05R can be configured through simple on-off of a switch or selection of a connector; the resistor comprises, in addition to the basic resistance value, a fixed value, the fixed value resistor being used to enlarge the multifunctional load

R after the above number and R in the attached figures 14-15 of the specification are the basic unit omega of the resistance.

In a first scheme, referring to fig. 1, the selectable load resistance circuit includes a plurality of first resistors connected in series, and a connector is disposed between adjacent first resistors; after any two connectors are connected with an external circuit, a first resistor between the two connectors is connected into the external circuit; when an external power supply is connected with different connector lugs, the resistor between the connector lugs is selected to be connected into the power supply detection circuit as the resistance value of the loader.

For example, the number of the resistors between different connector lugs is N, the resistance values of the resistors are all R, and the resistance value of the load access detection circuit is N × R; the resistance value is changed by changing the connection of an external power supply and different connector lugs.

For example: the first resistance comprises R1, R2.. Rn; a connector L1 is arranged between R1 and R2, and a connector L2...... Rn-1 is arranged between R2 and R3; when an external power supply is respectively connected with L1 and Ln-1, the resistors R2 and R3.. Rn-1 are connected into an external circuit; when the resistance load value required to be configured in the power supply detection process is 10R, and the resistance values of R1 and R2.. Rn are R, the external power supply and the connector are connected with L1 and L11; preferably, an input end L0 and an output end Ln are further arranged at the tail ends of the resistors R1 and Rn; after the L0 and Ln are connected to the external circuit, R1 and R2.

In a preferred embodiment, referring to fig. 2, based on the above embodiment, two ends of at least one first resistor are connected in parallel with a short-circuit switch; after the connection between the external power supply and the connector lug is determined, the resistance value of the power supply detection circuit connected to the loader can be changed through the on-off of the switch.

For example: the two ends of all the first resistors are connected with a short-circuit switch in parallel, and when the switch is closed, the first resistors connected with the open end in parallel are short-circuited; the number of the first resistors accessed to the detection circuit is N, wherein the number of the closed switches is M, and the resistance value of the load access detection circuit is (N-M) × R at the moment; the switches may be connected in parallel to part of the first resistors, or may be connected in parallel to all the first resistors.

For example: the series resistors R2 and R3.. to Rn-1 are connected with switches K2 and K3... to Kn-1 in parallel; when an external power supply is connected with L1 and Ln-1 respectively, the resistors R2 and R3. By closing the switch K2, the R2 is short-circuited, and the resistors connected to the external circuit at this time are R3 and R4. When the resistance load value required to be configured in the power supply detection process is 5R, and the resistance values of R1 and R2.. Ann are R, the connecting heads are connected with L1 and L11 and an external circuit; at the moment, the connector does not need to be replaced, and the switches K2 and K3. are closed.

In a preferred scheme, referring to fig. 3, at least one resistor is connected with a second resistor in parallel; the resistance value can be reduced and the power of the loader can be increased by connecting the second resistor in parallel; the second resistors may be connected in parallel to part of the first resistors, or may be connected in parallel to all the first resistors.

For example: a second resistor comprising R1A, R2a.... RnA; and the resistance values of the R1A and the R2a.... RnA are both R and are connected in parallel to two ends of the first resistor R1.... Rn, so that the power of the load is doubled.

In a preferred scheme, one end of the second resistor is directly connected with one end of the first resistor; the other end of the resistor is connected with a second resistor through a switch; when the switch is closed, the first resistor and the second resistor are connected in parallel; when the switch is turned off, it is equivalent to that only the first resistor is effective; the power value of the load device is selected by controlling the on-off of a switch between the first resistor and the second resistor; a switch can be arranged between part of the first resistor and the second resistor; switches may be provided between all the first resistors and the second resistors.

For example: a switch KnA is arranged between a switch K1A arranged between R1 and R1A and a switch K2A... between R2 and R2A, and a switch K2A.... between Rn and RnA is arranged, and the parallel relation between R2 and R2A can be disconnected by disconnecting the switch K2A., so that the power of the whole circuit is changed.

In the second scheme, the selectable load resistance value circuit comprises an input connecting end, an output connecting end and a plurality of first resistors which are connected in series between the input connecting end and the output connecting end, and two ends of at least one first resistor are connected with a short-circuit switch in parallel; the input connecting end and the output connecting end are respectively connected into an external power supply test circuit; the resistance value and the maximum power value of the load device connected into the test circuit can be directly adjusted through the switch, and the problem that the power cannot be increased when the power of the slide rheostat is small in resistance value is solved; the difference between the scheme and the first scheme is that a connector is not needed to be arranged between the first resistors, the whole circuit is directly connected into an external circuit, and the resistance value and the power value are regulated and controlled through a switch.

The other related optimized switch setting and the second resistor setting of the scheme have the same optimized scheme form as the first scheme; this is not described in detail.

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

In this example, see 4-5; the bottom plate is a PCB or a radiating fin 2; when the bottom plate is the radiating fin 2, a plurality of first resistors are connected in series and then fixed on one radiating fin 2, so that the radiation of maximum utilization is realized; when the bottom plate is a PCB, the plurality of first resistors are connected in series and then fixed on the PCB.

In a preferred embodiment, referring to fig. 6, 14 and 15, the base plate includes a heat sink 2 and a PCB; the first resistor is fixed on the radiating fin 2, and then the first resistor and the radiating fin 2 are fixed on the PCB; the radiating fins 2 are connected to radiate the resistors, so that the maximum power of the selectable load resistance value circuit can be increased to a certain extent.

Referring to fig. 10, a power detection circuit includes a multifunctional loader and a connection circuit; the connecting circuit is used for electrically connecting an external power supply and the selectable load resistance value circuit.

The connecting circuit comprises an input end and an output end; the input end comprises an alligator clip 1, and the alligator clip 1 is used for clamping a connector of the selectable load resistance value circuit; the output end is used for being electrically connected with an external power supply.

According to the specific scheme, the input end comprises one or more of a DC head, an AC head, a wire clamping seat and an alligator clip 1; but not limited thereto, including, for example, a USB interface or a type-c interface or a DC power interface of different diameter sizes; the external power supply can be electrically connected with the connecting circuit through the alligator clip 1 or a USB interface, a type-c interface or a DC power supply interface.

Referring to fig. 9, in a preferred embodiment, the power supply further 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 LEDs 1, LED2..... LED 8; indicating different voltage values of 100V, 80V, 60V, 48V, 36V, 20V, 12V and 5V, respectively.

In a preferred scheme, the output end of the connecting circuit comprises a positive contact and a negative contact, and the positive contact and the negative contact are respectively arranged on the front side and the back side of the PCB; after the output end is connected with an external power supply, an equivalent capacitor EC1 which is connected in parallel with the two ends of the external power supply is self-integrated between the positive contact and the negative contact.

In the prior art, the EMI value of a test power supply is tested by adopting a pure resistive load; the actual power supply product necessarily comprises a capacitive load besides a resistive load; the capacitive load has certain influence on the EMI of the power circuit, if the capacitive load is ignored during testing, the difference between the EMI value obtained during testing and the EMI value obtained during actual working of a product is larger, and the conditions that the product is qualified during testing and is unqualified during use can occur; in order to eliminate the influence, the invention respectively uses the positive contact and the negative contact of the connecting circuit to be arranged on the front surface and the back surface of the PCB; after the output end is connected with an external power supply, an equivalent capacitor EC1 which is connected in parallel with the two ends of the external power supply is self-integrated between the positive contact and the negative contact; during testing, the actual capacitive load of the product is arranged on two sides of the resistive load; eliminating the influence of capacitive load on EMI test; so that the test result is closer to the true value of the product in operation.

In the present embodiment, the equivalent capacitance EC1 value satisfies the formula: (C = S)/d; where C is the magnitude of the equivalent capacitance EC 1; s is the relative area of the two conductive layers on the back and the front of the PCB; is the dielectric constant of the PCB board; d is the thickness of the PCB; when the connecting circuit selects different connectors, the value of the equivalent capacitor EC1 is not changed; namely, when the resistive load value is changed, the capacitive load value is not influenced; the resistive load and the capacitive load are independent of each other.

In the present implementation, one or more equivalent capacitors EC1C may be additionally connected to the connection circuit; two ends of the equivalent capacitor EC1C are respectively connected with a pair of contacts of the connecting circuit; thereby connecting the equivalent capacitor EC1C in parallel across the equivalent capacitor EC 1; the number and the capacitance value of the equivalent capacitors EC1C can be selected according to the test requirements; or a part of the equivalent capacitor EC1C can be connected between the contacts in advance, and a switch can be connected between the capacitor and the contacts in series; whether the capacitor is connected with the equivalent capacitor EC1 in parallel or not is controlled by switching on and off the switch.

In this embodiment, the dimensions of the PCB board are: 302mm 148mm, thickness 1-1.6 cm; the connecting circuit is arranged on the front surface of the PCB; the connector is connected with the back surface of the PCB; the equivalent capacitance EC1 is formed with a value of 200-300 PF.

See FIGS. 11-13; FIG. 11 is a graph of EMI versus frequency for a 5V, 2A charger during actual operation; FIG. 12 is a diagram showing the relationship between EMI and frequency of a 5V, 2A charger directly connected in series with a plurality of resistors; wherein FIG. 13 is a graph of EMI versus frequency for a 5V, 2A charger when connected to the multi-function load in this example; wherein the load resistance value is 2.5R; from the figures it can be seen that: when the resistance loads are directly connected in series, the margin reaches 8dBuV, but the actual test result of the mobile phone is not only without the margin but also exceeds 3 dBuV, the waveform tested by the multifunctional load device is closer to the actual mobile phone charging effect, the test result is 4dBuV, and the test structure is closer to the actual value of the product in actual use.

The invention has the advantages that:

1. the multifunctional loader comprises a selectable load resistance value circuit and a bottom plate; the selectable load resistance value circuit is arranged on the bottom plate; the selectable load resistance value circuit comprises a plurality of different selectable resistance values and a plurality of different adjustable powers; the device can adapt to the requirements for voltage, current and power in different power supply detection processes, can avoid the trouble that the resistor needs to be configured in each test, and can break through the small resistor, so that the power cannot be greatly limited.

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

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

The above disclosure is only for a few specific embodiments of the present invention, but the present invention is not limited thereto, and any variations that can be made by those skilled in the art are intended to fall within the scope of the present invention.

Claims

1. A circuit capable of selecting load resistance is characterized by comprising a plurality of first resistors connected in series, wherein the plurality of first resistors connected in series form a resistor string; connectors are arranged at the head end and the tail end of the adjacent first resistor or the resistor string; after any two connectors are connected with the external circuit, all the first resistors between the two connectors are connected into the external circuit.

2. The selectable load resistance circuit of claim 1, wherein at least one of the first resistors is connected in parallel across the shorting switch.

3. The selectable load resistance circuit of claim 1, wherein at least one of said first resistors is connected in parallel with a second resistor.

4. A connection circuit comprising an input terminal and an output terminal; the input end is used for being electrically connected with a connector of the selectable load resistance circuit in claim 1; the output end is used for being electrically connected with an external power supply.

5. The connecting circuit of claim 4, wherein the input or output comprises one or more of a DC header, an AC header, a wire holder, and an alligator clip.

6. The connecting circuit of claim 4, wherein the output terminal comprises a positive contact and a negative contact, and the positive contact and the negative contact are respectively arranged on the front surface and the back surface of the PCB; after the output end is connected with an external power supply, an equivalent capacitor which is connected in parallel with the two ends of the external power supply is self-integrated between the positive contact and the negative contact.

7. The connection circuit of claim 6, further comprising a plug capacitor connected in parallel across the equivalent capacitor.

8. The connection circuit of claim 6, further comprising a display circuit comprising a plurality of voltage indicator lights; the voltage indicator lamp is used for displaying the power supply voltage and the loaded voltage.

9. A multifunctional load device, comprising a bottom plate and the circuit with selectable load resistance value as claimed in any one of claims 1 to 3, wherein the first resistor is connected in series and then arranged on the bottom plate; the bottom plate is a PCB or a radiating fin; the first resistor is arranged on the PCB or the heat sink; or the bottom plate comprises a radiating fin and a PCB, the first resistor is fixed on the radiating fin, and then the first resistor and the radiating fin are fixed on the PCB.

10. The multi-functional load according to claim 9, further comprising the connection circuit according to any one of claims 4 to 8, the connection circuit being disposed on a chassis.