Capacitance test module capable of realizing constant-current charging and discharging
By designing a capacitance test module including a processing module, a power supply module, a constant current source module and a acquisition and adjustment module, using a single constant current source module to provide constant current and achieve rapid switching of the charging and discharge state, the existing capacitance test methods have solved the problems of long response time and unstable waveforms, and achieved rapid response and stable waveform capacitance test effects.
Patent Information
- Application Number
- CN202420931035.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-04-30
- Publication Date
- 2025-03-11
- Estimated Expiration
- 2034-04-30
AI Technical Summary
The existing capacitance testing method requires two constant current sources to supply power separately, resulting in a long response time and a cut-top waveform at both ends of the capacitor, which cannot achieve rapid response and waveform stability.
A capacitance testing module including a processing module, a power supply module, a constant current source module and a acquisition and adjustment module is designed. Constant current is provided through a single constant current source module, and connected to the capacitor to be tested through a current feedback amplifier and an operational amplifier. The charging and discharging switch unit is used to achieve rapid switching of the charging and discharging state, ensuring the stability of the waveform at both ends of the capacitor.
The rapid response and waveform stability of capacitance test under a single constant current source drive are achieved, which greatly improves the time response of capacitance test and reduces the size and cost of the equipment.
Smart Images
Figure CN222599752U_ABST
Abstract
Description
Technical Field
[0001] The utility model is applied to the technical field of capacitor testing, and particularly relates to a constant current charging and discharging capacitor testing module. Background Art
[0002] With the rapid development of the information age, a variety of consumer electronic products are also filling our lives. Electronic products involve various electronic components, among which the accuracy of the capacitance on the circuit board will affect the performance of the electronic products. Therefore, the capacitance test must also be accurately measured to ensure the performance and life of the product. At present, LCR test instruments are almost always used for capacitance testing, but due to the large size of LCR test instruments, it is not convenient to complete the integration and miniaturization of the test equipment. In addition, LCR test instruments are expensive, complicated to operate, and take too long to operate.
[0003] Although there are designs for measuring capacitance using the constant current source charging method on the market at this stage, this is usually achieved by powering the capacitor charging and discharging separately with two constant current sources. Such a design has a long response time, and the waveforms at both ends of the capacitor are clipped.
[0004] If a capacitor test module can be designed that only requires a single constant current source for driving and can achieve fast response while ensuring stable waveforms at both ends of the capacitor, the above problems can be well solved. Utility Model Content
[0005] The technical problem to be solved by the utility model is to overcome the deficiencies of the prior art and provide a capacitor test module which only needs a single constant current source and can achieve fast response while ensuring constant current charging and discharging with stable waveforms at both ends of the capacitor.
[0006] The technical solution adopted by the utility model is: the utility model includes a processing module, a power supply module, a constant current source module and an acquisition adjustment module, the input end of the acquisition adjustment module is connected to the capacitor to be measured, the output end of the acquisition adjustment module is connected to the processing module, the power supply module is connected to the processing module, the constant current source module and the acquisition adjustment module for power supply, the constant current source module includes a current feedback amplifier, a first operational amplifier, and a charge and discharge switch unit, the output end of the current feedback amplifier and the input end of the first operational amplifier are both connected to the capacitor to be measured, the input end of the current feedback amplifier and the output end of the first operational amplifier are both connected to the common port of the charge and discharge switch unit, and the common port of the charge and discharge switch unit is connected to the charging end and the discharging end.
[0007] It can be seen from the above scheme that the processing module is used to process the capacitor terminal signal collected by the acquisition and adjustment module, and the power supply module is used to provide working current and voltage for each module. The constant current source module provides a constant current, which is connected to the capacitor to be measured through the current feedback amplifier and the first operational amplifier at the same time, and is coordinated by the charge and discharge switch, so that the input end of the current feedback amplifier and the output end of the first operational amplifier are turned on for the charging circuit or the discharge circuit, and the connection method is used to achieve rapid switching of the charge and discharge state, so that the waveform at both ends of the measured capacitor will not be clipped, which greatly improves the capacitor test time response. In addition, the overall structure of the utility model is simple, low in cost, easy to produce and integrated in the test equipment, takes up little space, and is conducive to the design of multi-channel test equipment.
[0008] A preferred solution is that the charge and discharge switch unit includes a first field effect transistor and a second field effect transistor, the input end of the first field effect transistor is connected to the charging end, the output end of the second field effect transistor is connected to the discharging end, and the output end of the first field effect transistor and the input end of the second field effect transistor are both connected to the common port.
[0009] A preferred solution is that a gear switching module is also provided between the constant current source module and the capacitor to be measured, the gear switching module includes a switch chip and a plurality of gear resistors, the input end of the switch chip is connected to the output end of the constant current source module, and the plurality of output ends of the switch chip are respectively connected to the capacitor to be measured through a plurality of the gear resistors.
[0010] A preferred solution is that the acquisition and adjustment module includes a control unit and a shaping output unit, the input end of the control unit is connected to the capacitor to be measured, the output end of the control unit is connected to the control end of the charge and discharge switch unit, the input end of the shaping output unit is connected to the charge and discharge switch unit and acquires the signal at the port, and the output end of the shaping output unit is connected to the processing module.
[0011] A preferred solution is that the control unit includes a second operational amplifier, a first comparator, a second comparator and a trigger, the input end of the second operational amplifier is connected to the capacitor to be measured, the negative input end of the first comparator and the positive input end of the second comparator are both connected to the output end of the second operational amplifier, the output ends of the first comparator and the second comparator are respectively connected to the two input ports of the trigger, and the output port of the trigger is connected to the control port of the charge and discharge switch unit.
[0012] A preferred solution is that the shaping output unit includes a third comparator, and an input port of the third comparator is connected to a control port of the charge and discharge switch unit.
[0013] A preferred solution is that the power supply module includes a power supply chip, a third operational amplifier and a fourth operational amplifier, the input end of the power supply chip is connected to the power supply, the output end of the power supply chip is connected to the third operational amplifier and the fourth operational amplifier in sequence, the charging end is connected to the output end of the third operational amplifier, and the discharging end is connected to the output end of the fourth operational amplifier. BRIEF DESCRIPTION OF THE DRAWINGS
[0014] Figure 1 It is a system block diagram of the utility model;
[0015] Figure 2 is a circuit schematic diagram in which the constant current source module is directly connected to the capacitor to be measured;
[0016] Figure 3 is a circuit schematic diagram showing that the constant current source module is connected to the capacitor to be measured through the gear switching module;
[0017] Figure 4 is a circuit schematic diagram of the shaping output unit;
[0018] Figure 5 is a circuit schematic diagram of the power supply module;
[0019] Figure 6 is a working signal waveform diagram of the control unit;
[0020] Figure 7 It is a signal waveform diagram at both ends of the capacitor to be tested collected by the shaping output unit. DETAILED DESCRIPTION
[0021] like Figure 1As shown, in this embodiment, the utility model includes a processing module 1, a power supply module 2, a constant current source module 3 and a collection and adjustment module 4, the input end of the collection and adjustment module 4 is connected to the capacitor 5 to be measured, the output end of the collection and adjustment module 4 is connected to the processing module 1, the power supply module 2 is connected to the processing module 1, the constant current source module 3 and the collection and adjustment module 4 for power supply, the constant current source module 3 includes a current feedback amplifier U1200, a first operational amplifier U1202A, and a charge and discharge switch unit, the output end of the current feedback amplifier U1200 and the input end of the first operational amplifier U1202A are both connected to the capacitor 5 to be measured, the input end of the current feedback amplifier U1200 and the output end of the first operational amplifier U1202A are both connected to the common port of the charge and discharge switch unit, and the common port of the charge and discharge switch unit is connected to the charging end PP1V and the discharging end PN1V. The current feedback amplifier U1200 is an amplifier chip of model LT1206, which has the function of maintaining stability under large capacitive loads and easily providing the large current required by the capacitive loads. The low differential gain and phase, wide bandwidth, and 250mA minimum output drive current enable it to obtain a more stable waveform signal during capacitance testing, thereby achieving very accurate capacitance data measurement. The first operational amplifier U1202A is a group of amplifier units of an operational amplifier chip of model AD8066ARZ-R7.
[0022] The charge and discharge switch unit includes a first field effect transistor Q1200 and a second field effect transistor Q1201, wherein the drain of the first field effect transistor Q1200 is connected to the charging terminal PP1V, the source of the second field effect transistor Q1201 is connected to the discharging terminal PN1V, the source of the first field effect transistor Q1200 is connected to the drain of the second field effect transistor Q1201, and the common port is therebetween. The gates of the first field effect transistor Q1200 and the second field effect transistor Q1201 are connected to the port of the acquisition and adjustment module 4. The first field effect transistor Q1200 and the second field effect transistor Q1201 are both field effect transistors of model 2N7002, and the charging and discharging circuits are respectively controlled by the first field effect transistor Q1200 and the second field effect transistor Q1201 to achieve the effect of rapid opening and closing.
[0023] like Figure 2 As shown, the constant current source module 3 is directly connected to the capacitor 5 to be tested, and outputs current through the resistor R1204, thereby realizing single-level capacitance testing. Figure 2 The middle capacitor C1207 is the capacitor 5 to be measured.
[0024] like Figure 3As shown, a gear switching module can also be set between the constant current source module 3 and the capacitor to be measured 5, and the output current regulation is realized by setting the gear switching module. In this embodiment, the gear switching module includes a switch chip U1201 of model ADG1419 and two gear resistors. The input end of the switch chip U1201 is connected to the output end of the constant current source module 3, and the two output ends of the switch chip U1201 are respectively connected to the capacitor to be measured 5 through the two gear resistors. The switch chip U1201 switches the conduction path so that the gear resistors in the access circuit are different. In this embodiment, the two gear resistors are used to adjust the output current to 200uA and 2mA respectively. Figure 3 The middle capacitor C1207 is the capacitor 5 to be measured.
[0025] The acquisition and adjustment module 4 includes a control unit and a shaping output unit, the input end of the control unit is connected to the capacitor to be measured 5, the output end of the control unit is connected to the control end of the charge and discharge switch unit, the input end of the shaping output unit is connected to the charge and discharge switch unit and collects the signal at the port, and the output end of the shaping output unit is connected to the processing module 1. The control unit is used to collect the state of the capacitor to be measured 5, and then control the charge and discharge switching.
[0026] like Figure 3 As shown, the control unit includes a second operational amplifier U1202B, a first comparator U1203, a second comparator U1205 and a trigger U1204, the input end of the second operational amplifier U1202B is connected to the capacitor 5 to be measured, the negative input end of the first comparator U1203 and the positive input end of the second comparator U1205 are both connected to the output end of the second operational amplifier U1202B, the output ends of the first comparator U1203 and the second comparator U1205 are respectively connected to the two input ports of the trigger U1204, and the two output ports of the trigger U1204 are respectively connected to the gates of the first field effect transistor Q1200 and the second field effect transistor Q1201. The second operational amplifier U1202B is another group of amplifier units of the operational amplifier chip of model AD8066ARZ-R7, which collects the electrical signal of the capacitor 5 to be measured. The first comparator U1203 and the second comparator U1205 are both ADCMP600BRJZ ultra-fast comparators of ADI Company. The two comparators form an AND gate, which compares the triangle wave collected by the second operational amplifier U1202B with a limited voltage and outputs a square wave. The output square wave is used as the input of the trigger U1204. The trigger U1204 outputs voltage to two output ports according to the input square wave level state, thereby controlling the switch state of the charge and discharge switch unit. The trigger U1204 is a SN74LS74A comparator device of TI Company.
[0027] like Figure 4 , Figure 6 and Figure 7 As shown, the shaping output unit includes a third comparator U1300, the input port of the third comparator U1300 is connected to one of the control signals of the charging and discharging switch unit, and in this embodiment, the charging loop control signal PON port is used as the input, and the third comparator U1300 is an ADCMP6002 ultra-fast comparator of ADI Company, and the output signal is sent to the processing module 1. In this embodiment, the processing module 1 is a processor card, and the FPGA part of the processor card processes the square wave output by the shaping output unit, and the FPGA part processes the obtained square wave frequency to calculate the output capacitance.
[0028] like Figure 5 As shown, the power supply module 2 includes a power chip U900, a third operational amplifier U601A and a fourth operational amplifier U601B. The input end of the power chip U900 is connected to the power supply, the output end of the power chip U900 is connected to the positive input end of the third operational amplifier U601A, the output end of the third operational amplifier U601A is connected to the negative input end of the fourth operational amplifier U601B, the charging end PP1V is connected to the output end of the third operational amplifier U601A, and the discharging end PN1V is connected to the output end of the fourth operational amplifier U601B. The power chip U900 is a step-down chip with a model of ADR4550BRZ, which converts the 12V DC voltage of the power supply input into a 5V DC voltage. The voltage is converted into the voltage ±1V required by the constant current source module 2 through the voltage division of the third operational amplifier U601A and the fourth operational amplifier U601B. The third operational amplifier U601A and the fourth operational amplifier U601B are two operational amplifier units of an operational amplifier chip with a model of OPA2196ID.
[0029] Although the embodiments of the present invention are described with practical solutions, they do not constitute limitations on the meaning of the present invention. For those skilled in the art, it is obvious to modify the implementation scheme and combine it with other solutions based on this description.
Claims
1. A constant current charging and discharging capacitor test module, comprising a processing module (1) and a power supply module (2), characterized in that: It also includes a constant current source module (3) and a collection and adjustment module (4), wherein the input end of the collection and adjustment module (4) is connected to the capacitor to be measured (5), the output end of the collection and adjustment module (4) is connected to the processing module (1), the power supply module (2) is connected to the processing module (1), the constant current source module (3) and the collection and adjustment module (4) for power supply, the constant current source module (3) includes a current feedback amplifier (U1200), a first operational amplifier (U1202A), and a charge and discharge switch unit, the output end of the current feedback amplifier (U1200) and the input end of the first operational amplifier (U1202A) are both connected to the capacitor to be measured (5), the input end of the current feedback amplifier (U1200) and the output end of the first operational amplifier (U1202A) are both connected to the common port of the charge and discharge switch unit, and the common port of the charge and discharge switch unit is connected to a charging end (PP1V) and a discharging end (PN1V).
2. A constant current charge and discharge capacitor test module according to claim 1, characterized in that: The charge and discharge switch unit comprises a first field effect tube (Q1200) and a second field effect tube (Q1201), the input end of the first field effect tube (Q1200) is connected to the charging end (PP1V), the output end of the second field effect tube (Q1201) is connected to the discharging end (PN1V), and the output end of the first field effect tube (Q1200) and the input end of the second field effect tube (Q1201) are both connected to the common port.
3. A constant current charge and discharge capacitor test module according to claim 1, characterized in that: A gear switching module is also provided between the constant current source module (3) and the capacitor to be measured (5), the gear switching module comprising a switch chip (U1201) and a plurality of gear resistors, the input end of the switch chip (U1201) being connected to the output end of the constant current source module (3), and the plurality of output ends of the switch chip (U1201) being connected to the capacitor to be measured (5) via the plurality of gear resistors.
4. The constant current charging and discharging capacitor test module according to claim 1, characterized in that: The acquisition and adjustment module (4) comprises a control unit and a shaping output unit, wherein the input end of the control unit is connected to the capacitor to be measured (5), the output end of the control unit is connected to the control end of the charge and discharge switch unit, the input end of the shaping output unit is connected to the charge and discharge switch unit and acquires the signal at the port, and the output end of the shaping output unit is connected to the processing module (1).
5. A constant current charge and discharge capacitor test module according to claim 4, characterized in that: The control unit comprises a second operational amplifier (U1202B), a first comparator (U1203), a second comparator (U1205) and a trigger (U1204); the input end of the second operational amplifier (U1202B) is connected to the capacitor (5) to be measured; the negative input end of the first comparator (U1203) and the positive input end of the second comparator (U1205) are both connected to the output end of the second operational amplifier (U1202B); the output ends of the first comparator (U1203) and the second comparator (U1205) are respectively connected to two input ports of the trigger (U1204); and the output port of the trigger (U1204) is connected to the control port of the charge and discharge switch unit.
6. A constant current charge and discharge capacitor test module according to claim 4, characterized in that: The shaping output unit comprises a third comparator (U1300), and an input port of the third comparator (U1300) is connected to a control port of the charge and discharge switch unit.
7. The constant current charging and discharging capacitor test module according to claim 1, characterized in that: The power supply module (2) comprises a power supply chip (U900), a third operational amplifier (U601A) and a fourth operational amplifier (U601B); the input end of the power supply chip (U900) is connected to the power supply; the output end of the power supply chip (U900) is connected to the third operational amplifier (U601A) and the fourth operational amplifier (U601B) in sequence; the charging end (PP1V) is connected to the output end of the third operational amplifier (U601A); and the discharging end (PN1V) is connected to the output end of the fourth operational amplifier (U601B).