Clamp for testing excitation power of crystal
By designing a fixture that includes a PCB board, crystal holder, variable resistor, and load capacitor, the problem of verifying the excitation power before crystal is mounted on the board is solved, enabling simple and efficient testing and reducing operational complexity and cost.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-06
- Publication Date
- 2026-03-06
AI Technical Summary
Existing technologies make it difficult to efficiently verify the excitation power of crystals before they are mounted on the board, resulting in complex and time-consuming testing. Furthermore, current testing after loading requires cutting boards or jumper wires.
A fixture for testing crystal excitation power is provided, including a PCB board, crystal holder, variable resistor, load capacitor and chip clock verification circuit. The excitation power of the crystal can be verified in advance by using an external test fixture, which simplifies the operation and reduces costs.
This enables rapid and convenient verification of excitation power before crystal loading, improving testing efficiency, reducing operational complexity and cost, and ensuring that the excitation power is within specifications.
Smart Images
Figure CN223977259U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of crystal testing technology, specifically a fixture for testing the excitation power of a crystal. Background Technology
[0002] Crystal excitation power refers to the power consumed by a crystal resonator during operation. The excitation power directly affects the crystal's stability and lifespan. When the chip provides excessive excitation power to the crystal, various problems can occur, including crystal overheating, increased internal losses, unstable operation, frequency deviation, signal amplitude fluctuations, or even oscillation failure, and shortened lifespan. Therefore, crystal excitation power matching testing is a crucial step in the design and testing of electronic products. The excitation power can be calculated using the formula P = I... 2 ×Re learned that our primary task is to measure the current it actually uses in the circuit. However, when we mount the crystal on the PCB and then perform its current test, we can avoid measuring the current by cutting the board or using jumpers. The testing process is complicated and time-consuming. Therefore, the fixture board circuit needs to be verified. How to complete the current test verification before the crystal is used on the board is a technical problem that needs to be solved. Utility Model Content
[0003] This invention provides a fixture for testing the excitation power of a crystal to solve the technical problem of how to complete the current test verification before the crystal is used on the board.
[0004] The technical solution of this utility model to solve the above-mentioned technical problems is as follows:
[0005] A fixture for testing crystal excitation power is provided, the fixture comprising:
[0006] One PCB board;
[0007] The PCB board is provided with a crystal socket, and the crystal socket is provided with pin a, pin b, pin c and pin d;
[0008] The first terminal connected to pin a of the crystal holder;
[0009] The second terminal connected to pin c of the crystal holder;
[0010] A variable resistor RX1 is connected in series between the second terminal and pin c of the crystal socket via two wires;
[0011] A load capacitor C1 has one end connected to pin a of the crystal socket, and the other end connected to ground and connected to pin b of the socket;
[0012] A load capacitor C2 has one end connected to pin c of the crystal holder and the other end connected to ground and connected to pin d of the holder;
[0013] And a chip clock verification circuit, which is connected to the first terminal and the second terminal via wires, for externally verifying the crystal clock signal.
[0014] Furthermore, the load capacitor C1 has a capacitance of 18pF. One end, connected to pin a of the crystal socket, is used to receive signals from the crystal, while the other end is connected to ground to ensure signal stability. The other end is connected to pin b of the crystal socket to form a charge accumulation circuit for the crystal in its working state.
[0015] Furthermore, the load capacitor C2 has a capacitance of 18pF, one end of which is connected to pin c of the crystal socket, and the other end is connected to ground and pin d of the crystal socket respectively, so as to form a balanced inductance circuit when the crystal is working.
[0016] Furthermore, the variable resistor RX1 is a sliding rheostat with a resistance adjustment range that corresponds to the negative resistance range required for the crystal to operate normally. It is used to measure the crystal's operating current and excitation power under different negative resistance conditions.
[0017] Furthermore, the crystal holder adopts a 4-pin SMT package to improve assembly accuracy and reduce the impact of the housing on test results.
[0018] Furthermore, both the first and second terminals are universal 3.5 mm female connectors to simplify the connection process with the chip clock verification circuit.
[0019] Furthermore, the fixture includes a test point for measuring current by clamping a current probe onto the variable resistor RX1, which is used to obtain the crystal's operating current without damaging the original circuit, and is used in conjunction with an oscilloscope to visually display the test data.
[0020] The beneficial effects of this invention are as follows: This invention provides a quick and convenient test scheme for crystal excitation power, allowing for a series of verifications of the crystal's performance before it is mounted on the board. Furthermore, the crystal excitation power can be adjusted by regulating the variable resistor in the circuit, obtaining multiple sets of data that meet both the excitation power requirements and the crystal's negative resistance requirements. This is highly beneficial for crystal performance verification during the R&D and design phase. Moreover, the technical solution of this invention is easy to implement and simple to operate. It allows for verification of whether the excitation power value of the crystal meets the specifications during actual operation using an external test fixture before the crystal is mounted on the board. This not only improves testing efficiency but also offers high cost-effectiveness due to the low manufacturing cost of the fixture. Attached Figure Description
[0021] Figure 1 This is a diagram of the test scheme for this utility model.
[0022] In the diagram: 1. PCB board; 2. Crystal socket; 3. First terminal; 4. Second terminal; 5. Measurement oscilloscope; 6. Chip clock verification circuit. Detailed Implementation
[0023] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this utility model, and should not be construed as limiting this utility model. Furthermore, it should be understood that the specific embodiments described herein are merely for explaining this utility model and are not intended to limit this utility model.
[0024] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, an electrical connection, or a connection that allows for communication; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.
[0025] The following disclosure provides numerous different embodiments or examples for implementing various structures of the present invention. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the scope of the invention. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, examples of various specific processes and materials are provided in this invention; however, those skilled in the art will recognize the application of other processes and / or the use of other materials.
[0026] The present invention provides the following preferred embodiments:
[0027] To ensure the crystal operates in a safe and compliant environment during normal use, its excitation power must be within the rated standard range. This necessitates verification of current and excitation power. Since crystals are significantly affected by external environmental factors such as temperature and altitude, verifying their proper functioning at different locations is costly. Testing the current of the crystal after it's installed in the product requires cutting boards and jumper wires for current probe testing, which is complex and time-consuming. This invention addresses these shortcomings by providing a fixture for testing crystal excitation power. This external testing fixture allows for pre-verification of whether the excitation power value meets specifications during actual crystal operation. Furthermore, the fixture is low-cost to manufacture and easy to operate.
[0028] like Figure 1 As shown, this utility model provides a fixture for testing the excitation power of a crystal, including a PCB board 1. The PCB board is provided with a crystal holder 2, a first terminal 3, a second terminal 4, a variable resistor RX1, a load capacitor C1, and a load capacitor C2. The crystal holder 2 has four pins. The first terminal 3 is connected to pin a of the crystal holder 2, and the second terminal 4 is connected to pin c of the crystal holder 2. The variable resistor RX1 is connected in series between the second terminal 4 and pin c of the crystal holder 2 by two wires. One end of the load capacitor C1 is connected to pin a of the crystal holder 2, and the other end is grounded. The grounded end of the load capacitor C1 is also connected to pin b of the crystal holder 2. One end of the load capacitor C2 is connected to pin c of the crystal holder 2, and the other end is grounded. The grounded end of the load capacitor C2 is also connected to pin d of the crystal holder 2. One end of the load capacitor C1 is grounded and connected to pin b of the crystal socket 2. One end of the load capacitor C2 is connected to pin c of the crystal socket 2, and the other end is grounded. The grounded end of the load capacitor C2 is also connected to pin d of the crystal socket 2. The capacitance of the load capacitor C1 is 18pF, the capacitance of the load capacitor C2 is 18pF, the variable resistor RX1 is an adjustable sliding rheostat within the normal negative resistance of the crystal, the crystal socket is a 4-pin SMT surface mount, and the first and second terminals are universal 3.5mm female connectors.
[0029] The working principle of this invention is as follows: First, the fixture is connected to the chip clock verification circuit 6 via a cab LE cable using a first and second socket to provide an external working circuit for the crystal. When the crystal to be tested is soldered onto the crystal socket 2, the crystal begins to output a crystal oscillator to the external circuit. In the entire working loop, the variable resistor RX1 on the fixture board is connected in series with wires to provide a test point for the working current of the crystal. No board cutting or jumpers are required. The oscilloscope 5 is connected to a current probe and directly clamped at the test point to perform current testing. The variable resistor RX1 can also be finely adjusted. As long as the chip clock verification circuit 6 is working normally, the negative resistance capability of the crystal can be verified, and the corresponding crystal current value under each negative resistance can be verified. Thus, the crystal current value can be calculated using the formula P = I 2 The excitation power of the crystal can be calculated by multiplying Re, where Re is the equivalent resistance of the crystal, and its value is known.
[0030] When using the fixture of this invention for verification, the crystal device to be tested is soldered onto the crystal socket 2. The fixture is connected to the chip clock verification circuit 6 via the first and second sockets using a cabling cable. At this time, the crystal outputs a clock signal to the IC in the verification circuit for operation. The current probe is directly clamped to the wire connected to the variable resistor RX1 and connected to the oscilloscope 5 for current testing. When the resistance value of the variable resistor RX1 is adjusted to 100 ohms, the IC in the chip clock verification circuit 6 can operate normally. The measured current value I1 is read from the oscilloscope, and the current is calculated using the formula P = I... 2 The excitation power of the crystal can be calculated as P1 using the formula P = I2² × Re. Then, the resistance of the variable resistor RX1 is adjusted to 200 ohms. The IC in the chip clock verification circuit 6 works normally. The current value I2 measured on the oscilloscope is read. The excitation power of the crystal can be calculated using the formula P = I2² × Re. According to industry standards, the excitation power is required to be less than 300 microwatts (µW). If P1 and P2 are less than 300µW, it means the crystal and negative resistance circuit can be used in this environment. If P1 and P2 are greater than 300µW, it means the excitation power is exceeded. In this case, the resistance of the variable resistor RX1 needs to be increased to reduce the current through the crystal and thus lower the excitation power. It is important to note that when increasing the resistance of the variable resistor RX1, close attention must be paid to whether the IC in the chip clock verification circuit 6 works normally. Excessive negative resistance adjustment may cause the crystal to stop oscillating.
[0031] This achieves the excitation power testing of the crystal; the solution is simple to implement, low in cost, and highly cost-effective. It is suitable for the product development stage and provides a low-cost, easy-to-operate solution.
[0032] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and not to limit it; although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this utility model.
Claims
1. A jig for testing the power of a crystal, characterized by, The clamp comprises: a PCB board (1); a crystal holder (2) is arranged on the PCB board (1), and the crystal holder (2) is provided with pins a, b, c and d; a first terminal (3) connected with the pin a of the crystal holder (2); a second terminal (4) connected with the pin c of the crystal holder (2); a variable resistor RX1 connected between the second terminal (4) and the pin c of the crystal holder (2) through two wires in series; a load capacitor C1, one end of which is connected with the pin a of the crystal holder (2), the other end of which is connected with the ground and the pin b of the crystal holder (2); a load capacitor C2, one end of which is connected with the pin c of the crystal holder (2), the other end of which is connected with the ground and the pin d of the crystal holder (2); and a chip clock verification circuit (6) connected with the first terminal (3) and the second terminal (4) through wires, which is used for verifying the crystal clock signal externally.
2. The test fixture for testing the power of a crystal excitation as defined in claim 1, wherein, The load capacitor C1 has a capacitance of 18 pf, one end of which is connected with the pin a of the crystal holder (2) to receive the signal from the crystal, and the other end of which is connected with the ground to ensure the stability of the signal, and the other end of which is connected with the pin b of the crystal holder (2) to form a charge accumulation loop of the crystal in the working state.
3. The test fixture for testing the power of a crystal excitation as defined in claim 1 wherein, The load capacitor C2 has a capacitance of 18 pf, one end of which is connected with the pin c of the crystal holder (2), and the other end of which is connected with the ground and the pin d of the crystal holder (2) respectively to form a balanced inductance loop of the crystal in the working state.
4. The test fixture for testing the power of a crystal excitation as defined in claim 1 wherein, The variable resistor RX1 is a slide rheostat, and the resistance adjusting range is the required negative resistance range of the crystal in the normal working state, which is used for measuring the working current and excitation power of the crystal under different negative resistance conditions.
5. The test fixture for testing the power of a crystal excitation as defined in claim 1 wherein, The crystal holder (2) adopts a 4-pin SMT packaging form to improve the assembly precision and reduce the influence of the shell on the test results.
6. The test fixture for testing the power of a crystal excitation as defined in claim 1 wherein, The first terminal (3) and the second terminal (4) are both universal 3.5 mm female head holders to simplify the connection process with the chip clock verification circuit (6).
7. The jig for testing the crystal excitation power according to any one of claims 1 to 6, characterized by, The clamp comprises a test point for measuring the current by clamping a current probe on the variable resistor RX1, which is used for obtaining the working current of the crystal without damaging the original circuit, and is used for intuitively displaying the test data in cooperation with an oscilloscope (5).