Program-controlled capacitance output device

Abstract

The invention provides a programmed capacitance output device which comprises a processor circuit, a driving circuit, a first relay set, a capacitor set, a second relay set and a communication and interface circuit which are connected in sequence, the processor circuit is connected with the communication and interface circuit, and the communication and interface circuit is connected with upper computer software and a product to be tested. The driving circuit is connected with the second relay group; the output end of each capacitor in the capacitor bank can output three capacitance values through on-off setting of the relay, and any capacitance output value of a specified capacitance difference interval within a specified capacitance range can be obtained by adjusting the capacitance value of each capacitor. According to the invention, the multi-group capacitor input capability is provided for the segmented capacitive converters with different measuring ranges, the test requirements in various test scenes such as aging, temperature circulation and vibration when the converters are batched are met, and the test resources and the test cost can be saved to the greatest extent.

Description

Technical Field

[0001] The present invention relates to the technical field of electrical components, and in particular to a programmable capacitance output device. Background Art

[0002] Sensors based on the segmented capacitance measurement principle separate the front-end sensitive capacitance module from the back-end capacitance measurement and conversion circuitry to avoid environmental influences. This makes it impossible to perform simultaneous tests on the front-end sensitive capacitance module and the back-end capacitance measurement and conversion circuitry. Alternatively, they can perform simultaneous tests but not on multiple operating conditions. Currently, fixed-value capacitance boxes are bulky, slow to operate, and offer limited capacitance inputs, making them unable to meet the multi-channel capacitance input requirements of mass-produced sensors.

[0003] Therefore, there is a need for an analog front-end sensitive capacitance module that can provide a variable input for the back-end capacitance measurement conversion circuit and evaluate its functional performance. Summary of the Invention

[0004] The present invention aims to solve the problem of testing sensors based on the segmented capacitance measurement principle and provides a programmable capacitance output device with the ability to provide multiple sets of capacitance inputs for segmented capacitance converters of different ranges, meeting the testing requirements of various test scenarios such as aging, temperature cycling and vibration during batch production of converters, thereby saving testing resources and experimental costs to the greatest extent possible.

[0005] The present invention provides a programmable capacitance output device, comprising a processor circuit, a drive circuit, a first relay group, a capacitor group, a second relay group and a communication and interface circuit connected in sequence, wherein the processor circuit is connected to the communication and interface circuit, the communication and interface circuit is connected to a host computer software and a product to be tested, and the drive circuit is connected to the second relay group;

[0006] The capacitor group includes at least two capacitors connected in parallel, the output end includes terminal 1, terminal 2 and a common end, and the first relay group includes at least two relays;

[0007] The number of relays in the first relay group is twice the number of capacitors in the capacitor group. One end of each capacitor is connected to terminal 1 and terminal 2 respectively through two relays in the first relay group, and the other end is connected to the common terminal. The output end of each capacitor in the capacitor group can output three capacitance values ​​by setting the relay on and off. By adjusting the capacitance value of each capacitor, any capacitance output value with a specified capacitance difference interval within a specified capacitance range can be obtained.

[0008] The processor circuit receives signals from the host computer and sends control signals to the drive circuit through the I / O port, controlling the drive circuit to select the corresponding relays in the first relay group to control the output capacitance value of the capacitor group; the drive circuit selects the corresponding relays in the second relay group and controls the drive circuit to select the external coaxial contacts of the corresponding product to provide output capacitance for the external product.

[0009] The programmable capacitance output device of the present invention is preferably configured such that the capacitance group includes capacitance values ​​of C1, ..., C i ,...,C n n fixed-value capacitors, each capacitor is switched on and off by two relays of the first relay group to control the output capacitance between terminal 1 and the common terminal, and the output capacitance between the common terminal and terminal 2;

[0010] The output capacitance △C of the capacitor bank is the coefficient k of each fixed value capacitor. i and capacitance C i The product of capacitance C i To balance the ternary number The product of the output capacitance difference interval g, k i ∈{-1,0,1}.

[0011] The programmable capacitance output device described in the present invention is preferably:

[0012]

[0013] Among them, C 奇 is the capacitance value between terminal 1 and the common terminal of the capacitor group, C 偶 is the capacitance value between the two terminals and the common terminal of the capacitor group;

[0014]

[0015] Among them, C max is the maximum demand value of △C.

[0016] In the programmable capacitance output device described in the present invention, as a preferred embodiment, g can be as small as 0.1 pF;

[0017] k i When it is -1, the relay connected to terminal 1 is disconnected and the relay connected to terminal 2 is closed;

[0018] k i When it is 0, the relay connected to terminal 1 and the relay connected to terminal 2 are both disconnected;

[0019] k i When it is 1, the relay connected to terminal 1 is closed and the relay connected to terminal 2 is open.

[0020] In the programmable capacitance output device of the present invention, as a preferred embodiment, the number of the communication and interface circuits is at least two, and each communication and interface circuit includes an output terminal 1, an output common terminal, and an output terminal 2;

[0021] The second relay group includes m relay groups connected in parallel, each relay group includes a 1-end relay, a common-end relay, and a 2-end relay connected in parallel, and capacitors C0 connected between the 1-end relay and the common-end relay, and between the common-end relay and the 2-end relay respectively;

[0022] One end of the 1-terminal relay is connected to terminal 1 of the capacitor bank, and the other end is connected to terminal 1 of the output terminal. One end of the common-terminal relay is connected to the common end of the capacitor bank, and the other end is connected to the common end of the output terminal. One end of the 2-terminal relay is connected to terminal 2 of the capacitor bank, and the other end is connected to terminal 2 of the output terminal.

[0023] When there is no capacitor output, capacitor C0 can determine the status of the product under test.

[0024] In the programmable capacitance output device described in the present invention, as a preferred embodiment, the processor circuit includes a processor chip and a peripheral clock, power conversion and programming interface circuit; the drive circuit includes a multiplexer chip and a driver chip;

[0025] The communication and interface circuits include RS422 or RS485 serial communication interface circuits, Ethernet interface circuits and coaxial connectors.

[0026] The relays of the first relay group and the second relay group are both reed relays;

[0027] The capacitance value of each capacitor in the capacitor group is different, and the ratio of two adjacent capacitance values ​​is 3;

[0028] The printed circuit board of the processor circuit, the printed circuit board of the drive circuit, the first relay group, the capacitor group, the second relay group and the coaxial connectors of the communication and interface circuits are all shielded to the ground.

[0029] In the programmable capacitance output device of the present invention, preferably, the number of capacitor groups is at least two, providing capacitors with different capacitance ranges and capacitance difference intervals for the product to be tested;

[0030] Each capacitor group is connected to a communication and interface circuit through the second relay group, and the communication and interface circuit has at least one output.

[0031] The programmable capacitance output device of the present invention is preferably used in any of the following test scenarios: batch aging test, temperature cycle test or vibration test of sensors based on the segmented capacitance measurement principle;

[0032] Before testing, the number of capacitors n in the capacitor group and the fixed capacitance of each capacitor are obtained by the required capacitance difference interval g and the required capacitance range, and the capacitor group is built and assembled to obtain a programmable capacitance output device;

[0033] During the test, the product to be tested is connected to the communication and interface circuits, and the on and off of the first relay group is controlled by the host computer software to provide the required test capacitance for the product to be tested.

[0034] The programmable capacitance output device described in the present invention is a preferred embodiment. When two or more products to be tested are subjected to batch aging test or temperature cycle test, all the products to be tested are connected to the communication and interface circuits respectively and placed in the batch aging test equipment or temperature cycle test equipment. When performance testing is required during the aging test or temperature cycle test, the upper computer software controls the on and off of the first relay group and the second relay group respectively to provide the required test capacitance for the products to be tested.

[0035] The programmable capacitance output device described in the present invention is a preferred embodiment. When the specified capacitance difference intervals of the products to be tested are different or the capacitance ranges are incompatible, at least two capacitance groups are provided in the programmable capacitance output device. All the products to be tested are connected to the communication and interface circuits respectively and then placed in batch aging test equipment or temperature cycling test equipment. When performance testing is required during the aging test or temperature cycling test, the on and off of the first relay group and the second relay group are respectively controlled by the upper computer software to provide different specified capacitance difference intervals and capacitance ranges for the products to be tested.

[0036] The analog capacitor output terminal of the above segmented capacitor converter is in a three-terminal form, "terminal 1", "common terminal" and "terminal 2". An input capacitor C is required between "terminal 1" and "common terminal". 奇 An input capacitor C is required between "Terminal 2" and "Common Terminal". 偶 . C 奇 The capacitance value and C 偶 The difference in capacitance needs to be within ±C max Changes between.

[0037] The present invention has the following advantages:

[0038] (1) The present invention can provide input capacitance for multiple segmented capacitive principle products with the same range or different ranges, and can also provide a single fixed-value capacitor or multiple fixed-value capacitors for multiple segmented capacitive principle products at the same time, which can adapt to the use scenario where capacitance input is required for long-term power-on testing.

[0039] (2) The present invention can communicate with a host computer through a serial port or a network port, and can programmatically switch multiple capacitors with different fixed values ​​and output them to multiple products in a time-sharing manner.

[0040] (3) The present invention can provide ground shielding from capacitors, reed relay switches, printed circuit boards to coaxial connectors, eliminating the influence of inter-circuit interference and distributed capacitance on test accuracy, and the minimum interval of the difference between the two output capacitors is 0.1pF.

[0041] (4) The present invention has the ability to provide multiple sets of capacitor inputs for segmented capacitive converters of different ranges, meeting the testing requirements of various test scenarios such as aging, temperature cycling and vibration during converter batch production, and can maximize the savings in testing resources and test costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is a block diagram of the principle of a programmable capacitance output device;

[0043] Figure 2 This is a schematic diagram of a single capacitor control circuit for a programmable capacitor output device;

[0044] Figure 3 This is a schematic diagram of a single-group capacitor control circuit for a programmable capacitor output device;

[0045] Figure 4 The schematic diagram of a single-group capacitor output gating control circuit for a programmable capacitor output device is shown in FIG.

[0046] Reference numerals:

[0047] 1. Processor circuit; 2. Drive circuit; 3. First relay group; 4. Capacitor group; 5. Second relay group; 51. Relay group; 511. 1-terminal relay; 512. Common-terminal relay; 513. 2-terminal relay; 6. Communication and interface circuit. DETAILED DESCRIPTION

[0048] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0049] Example 1

[0050] like Figures 1 to 3 As shown, a programmable capacitance output device includes a processor circuit 1, a drive circuit 2, a first relay group 3, a capacitance group, a second relay group 5 and a communication and interface circuit 6;

[0051] Processor circuit 1 includes a processor chip and peripheral clock, power conversion, and programming interface circuits. Communication and interface circuit 6 includes RS422 or RS485 serial communication interface circuits, Ethernet interface circuits, and coaxial connectors. Driver circuit 2 includes a multiplexer chip and a driver chip, which activate and deactivate the reed relays in first reed relay group 3 and second reed relay group 5.

[0052] The processor circuit 1 receives the host computer signal and sends the control signal to the drive circuit 2 through the I / O port, controls the drive circuit 2 to select the corresponding relay in the first relay group 3, and realizes the control of the output capacitance value; controls the drive circuit 2 to select the corresponding relay in the second relay group 5, and controls the drive circuit 2 to select the external coaxial contact of the corresponding product to provide output capacitance for the external product.

[0053] Each capacitor group 4 of the plurality of capacitor groups is composed of multiple fixed-value capacitors. Each capacitor group 4 is composed of n fixed-value capacitors with capacitances of C1, C2, ..., Cn. A single fixed-value capacitor is controlled by two switches. The on / off state of the two switches determines the coefficient of the capacitor to be one of {-1, 0, 1};

[0054] The first relay group 3 is a reed relay, which is used to connect and disconnect each capacitor in the capacitor group with "terminal 1" and "terminal 2".

[0055] The second relay group 5 is a reed relay, which is used to select the connection and disconnection of the corresponding points of "end 1", "common end" and "end 2" of the coaxial connectors of n products and "end 1", "common end" and "end 2" of the capacitor group.

[0056] The second relay group 5 includes m relay groups 51 connected in parallel, each relay group 51 includes a 1-end relay 511, a common-end relay 512, and a 2-end relay 513 connected in parallel, and a capacitor C0 connected between the 1-end relay 511 and the common-end relay 512, and between the common-end relay 512 and the 2-end relay 513 respectively;

[0057] One end of the 1-terminal relay 511 is connected to the 1-terminal of the capacitor bank 4, and the other end is connected to the 1-terminal of the output terminal. One end of the common-terminal relay 512 is connected to the common end of the capacitor bank 4, and the other end is connected to the common end of the output terminal. One end of the 2-terminal relay 513 is connected to the 2-terminal of the capacitor bank 4, and the other end is connected to the 2-terminal of the output terminal.

[0058] Each capacitor group 4 of the plurality of capacitor groups is composed of a plurality of fixed value capacitors. Each capacitor group is composed of a plurality of fixed value capacitors. i ,...C n , consisting of a total of n fixed-value capacitors.

[0059] Each capacitor bank 4 outputs "C 奇 The capacitance value of "C 偶 The difference in capacitance is as follows:

[0060]

[0061] Ci=g*3 (i-1) (2)

[0062] Where g is the interval of the required output capacitance difference. For example, the interval of 0.1, 0.2, 0.7, 0.8 is 0.1; the interval of 1, 2, 7, 8 is 1; and the interval of 10, 20, 70, 80 is 10.

[0063] is a balanced ternary number.

[0064] ki∈{-1,0,1}, is the coefficient of each fixed value capacitor.

[0065] If you need to output △C(C 奇 -C 偶 ) is between -120pF and +120pF with a 1pF interval. 奇 and C 偶 Capacitors. Formula 3 can be used to determine the required number of capacitors, n, to be 5. Formula 2 can be used to determine the five fixed capacitor values, 1pF, 3pF, 9pF, 27pF, and 81pF.

[0066]

[0067] By using these five fixed-value capacitors and combining the coefficient k of each fixed-value capacitor, it is possible to achieve a △C value of any one of -120pF, -119pF, -118pF, ..., 119pF, and 120pF.

[0068] If you need to output a △C value between -100pF and +100pF, with a C interval of 0.1pF 奇 and C 偶 Capacitors. Formula 3 can be used to determine the required number of capacitors, n, to be 7. Formula 2 can be used to determine the 7 fixed capacitor values ​​to be 0.1pF, 0.3pF, 0.9pF, 2.7pF, 8.1pF, 24.3pF, and 72.9pF.

[0069] By using these seven fixed-value capacitors and combining the coefficient k of each fixed-value capacitor, it is possible to achieve a △C value of any one of -100pF, -99.9pF, -99.8pF, ..., 99.9pF, and 100pF.

[0070] If the output △C value needs to be between -1000pF and +1000pF, the interval of C is 10pF. 奇 and C 偶 Capacitors. Formula 3 can be used to determine the required number of capacitors, n, to be 5. Formula 2 can be used to determine the five fixed capacitor values ​​to be 10pF, 30pF, 90pF, 270pF, and 810pF.

[0071] By using these five fixed-value capacitors and combining the coefficient k of each fixed-value capacitor, it is possible to achieve a △C of any value among -1000pF, -990pF, -980pF, ..., 990pF, and 1000pF.

[0072] In this embodiment, ground shielding can be provided from the capacitor, the reed relay switch, the printed circuit board to the coaxial connector, thereby eliminating the influence of inter-circuit interference and distributed capacitance on the test accuracy.

[0073] like Figure 2 As shown, in a single capacitor control circuit, the on and off of two switches are controlled by relays to achieve the coefficient k in formula 1 i The corresponding relationship between the coefficient value and the switch on / off state is shown in Table 1.

[0074] Table 1 Implementation method of single capacitance coefficient

[0075] Serial number coefficient K1 status K2 status 1 -1 disconnect closure 2 0 disconnect disconnect 3 1 closure disconnect

[0076] like Figure 3 As shown in the figure, the "1 terminal", "common terminal" and "2 terminal" of multiple capacitor control circuits are connected together to form a capacitor group. The final output capacitance of the "1 terminal" and "common terminal" of the capacitor group is "C 奇 The final output capacitance between "Terminal 2" and "Common" is "C 偶 ".C 奇 -C 偶 The value of can be calculated by formula 1.

[0077] like Figure 4 As shown in the figure, in the single group capacitor control circuit, the current tested product is selected through the selection and driving circuit, and the group capacitor output "C 奇 ” and “C 偶 "The capacitor is output to the current product under test. The output terminal C0 capacitor is used to determine the status of the product when the second relay group of the current product is not connected, to prevent the product from being powered on and running in an uncertain state. At this time, the C generated by the ternary balance 奇 and C 偶 Not output to the current product.

[0078] Determines the product status when there is no capacitance input.

[0079] The first relay group 3 can make the capacitor group 4 output C0 and many different fixed values ​​C by balancing the ternary system. j These two capacitors can be used as input for many products with the same range for testing. Figure 4 In the implementation shown, the three switches KA11\KA12\KA13 of KA1 are all on, and the switches of other KAx are all off. jand C0 provide input to product A1, while the inputs of other products are disconnected.

[0080] The fixed-value capacitors C1, C2, ..., Cn mentioned in the present invention can be implemented by using one capacitor or multiple capacitors connected in parallel.

[0081] During the burn-in test or temperature cycle test, each product is usually input by two C0s. The product is in the zero state and only requires a fixed capacitor to prevent interference from affecting the internal components. During the burn-in test, different capacitance values ​​are input to each product through a programmable capacitance output device to test the linearity performance of the product. Products are tested in sequence. For products of the same type, only one product is tested at the same time.

[0082] Temperature cycling involves testing products in turn after a period of high or low temperature holding. During each product test, the programmable capacitor output device switches to a different input capacitor. The remaining time, the capacitors are not switched, and only the two C0s are used as inputs.

[0083] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A programmable capacitance output device, characterized in that: The invention comprises a processor circuit (1), a drive circuit (2), a first relay group (3), a capacitor group (4), a second relay group (5) and a communication and interface circuit (6) which are connected in sequence, wherein the processor circuit (1) is connected to the communication and interface circuit (6), the communication and interface circuit (6) is connected to the host computer software and the product to be tested, and the drive circuit (2) is connected to the second relay group (5); The capacitor group (4) includes at least two capacitors connected in parallel, the output ends include terminal 1, terminal 2 and a common end, and the first relay group (3) includes at least two relays; The number of relays in the first relay group (3) is twice the number of capacitors in the capacitor group (4); one end of each capacitor is connected to end 1 and end 2 respectively through two relays in the first relay group (3), and the other end is connected to a common end; the output end of each capacitor in the capacitor group (4) can output three capacitance values ​​by the on-off setting of the relay, and any capacitance output value with a specified capacitance difference interval within a specified capacitance range can be obtained by adjusting the capacitance value of each capacitor; The processor circuit (1) receives a host computer signal and sends a control signal to the drive circuit (2) through an I / O port, thereby controlling the drive circuit (2) to select corresponding relays in the first relay group (3) to control the output capacitance value of the capacitor group (4); the drive circuit (2) selects corresponding relays in the second relay group (5), and controls the drive circuit (2) to select external coaxial contacts of corresponding products, thereby providing output capacitance for external products.

2. The programmable capacitance output device according to claim 1, characterized in that: The capacitor group (4) includes capacitors C1, ..., C i ,...,C n n fixed-value capacitors, each capacitor is switched on and off by two relays of the first relay group (3) to control the output capacitance between terminal 1 and the common terminal, and the output capacitance between the common terminal and terminal 2; The output capacitance ΔC of the capacitor group (4) is the coefficient k of each fixed value capacitor. i and capacitance C i The product of capacitance C i To balance the ternary number The product of the output capacitance difference interval g, k i ∈{-1,0,1}.

3. The programmable capacitance output device according to claim 2, characterized in that: Among them, C 奇 is the capacitance value between terminal 1 and the common terminal of the capacitor group (4), C 偶 is the capacitance value between the two terminals and the common terminal of the capacitor group (4); Among them, C max is the maximum demand value of △C.

4. The programmable capacitance output device according to claim 2, wherein: The minimum value of g can be 0.1pF; k i When it is -1, the relay connected to terminal 1 is disconnected and the relay connected to terminal 2 is closed; k i When it is 0, the relay connected to terminal 1 and the relay connected to terminal 2 are both disconnected; k i When it is 1, the relay connected to terminal 1 is closed and the relay connected to terminal 2 is open.

5. The programmable capacitance output device according to claim 1, characterized in that: The number of the communication and interface circuits (6) is at least two, and each of the communication and interface circuits (6) includes an output terminal 1, an output common terminal, and an output terminal 2; The second relay group (5) includes m relay groups (51) connected in parallel, each relay group (51) includes a 1-end relay (511), a common-end relay (512), and a 2-end relay (513) connected in parallel, and a capacitor C0 is connected between the 1-end relay (511) and the common-end relay (512), and between the common-end relay (512) and the 2-end relay (513), respectively; One end of the one-terminal relay (511) is connected to one end of the capacitor group (4) and the other end is connected to the output end 1; one end of the common-terminal relay (512) is connected to the common end of the capacitor group (4) and the other end is connected to the output end common end; one end of the two-terminal relay (513) is connected to two ends of the capacitor group (4) and the other end is connected to two ends of the output end; When there is no capacitance output, the capacitor C0 can determine the status of the product under test.

6. The programmable capacitance output device according to claim 1, characterized in that: The processor circuit (1) includes a processor chip and a peripheral clock, power conversion and programming interface circuit; the drive circuit (2) includes a multiplexer chip and a drive chip; The communication and interface circuit (6) comprises an RS422 or RS485 serial communication interface circuit, an Ethernet interface circuit and a coaxial connector. The relays of the first relay group (3) and the second relay group (5) are both reed relays; The capacitance value of each capacitor in the capacitor group (4) is different, and the ratio of two adjacent capacitance values ​​is 3; The printed circuit board of the processor circuit (1), the printed circuit board of the drive circuit (2), the first relay group (3), the capacitor group (4), the second relay group (5) and the coaxial connector of the communication and interface circuit (6) are all shielded from the ground.

7. The programmable capacitance output device according to claim 1, characterized in that: The number of the capacitor groups (4) is at least two, providing capacitors with different capacitance ranges and capacitance difference intervals for the product to be tested; Each of the capacitor groups (4) is connected to a communication and interface circuit (6) via the second relay group (5), and the communication and interface circuit (6) has at least one output.

8. The programmable capacitance output device according to any one of claims 2 to 7, characterized in that: The programmable capacitance output device is used in any of the following test scenarios: batch aging test, temperature cycle test or vibration test of sensors based on the segmented capacitance measurement principle; Before testing, the number n of capacitors in the capacitor group (4) and the fixed capacitance of each capacitor are obtained by using the required capacitance difference interval g and the required capacitance range, and the capacitor group (4) is constructed and assembled to obtain the programmable capacitance output device; During testing, the product to be tested is connected to the communication and interface circuit (6), and the on and off of the first relay group (3) is controlled by the host computer software to provide the required test capacitance for the product to be tested.

9. The programmable capacitance output device according to claim 8, characterized in that: When two or more products to be tested are subjected to batch aging test or temperature cycle test, all the products to be tested are connected to the communication and interface circuit (6) and then placed in batch aging test equipment or temperature cycle test equipment. When performance test is required during the aging test or temperature cycle test, the on and off of the first relay group (3) and the second relay group (5) are controlled by the host computer software to provide the required test capacitance for the products to be tested.

10. The programmable capacitance output device according to claim 9, characterized in that: When the specified capacitance difference intervals of a plurality of the products to be tested are different or the capacitance ranges are incompatible, at least two of the capacitance groups (4) are provided in the programmable capacitance output device, and all the products to be tested are respectively connected to the communication and interface circuit (6) and then placed in a batch aging test device or a temperature cycle test device. When a performance test is required during the aging test or the temperature cycle test, the on and off of the first relay group (3) and the second relay group (5) are respectively controlled by the host computer software to provide different specified capacitance difference intervals and capacitance ranges for the products to be tested.

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