DIN EN 60444-8:2017-11

This part of IEC 60444 describes test fixtures suitable for leadless surface mounted quartz crystal units in enclosures as defined in IEC 61837. These fixtures allow the measurement of (series) resonance frequency, (series) resonance resistance, and equivalent electrical circuit parameters using the measurement techniques specified in IEC 60444-5 and for the determination of load resonance frequency and load resonance resistance according to IEC 60444-4 and IEC 60444-11. Two test fixtures are described in this document. One is a fixture in which the network circuit is used with electrical values in line with IEC 60444-1 for transmission measurements up to 500 MHz. This fixture includes optional means to add physical load capacitors for the measurement of load resonance parameters up to 30 MHz in accordance with IEC 60444-4. The range of load capacitance is 10 pF or more. Calibration of the measurement system and CL adapter board are explained. On the other hand, a fixture based on the reflection method, suitable for a frequency range up to 1 200 MHz. No provisions for adding a physical load capacitance are anticipated. Load resonance parameters can be measured by using the method of IEC 60444-11. The frequency measurement range is between 1 MHz and 1 200 MHz and is limited to 1 MHz to 30 MHz when a physical load capacitance is used. The fixture and the measurement procedure for (series) resonant frequency, (series) resonant resistance and the parameters of the equivalent circuit shall be defined between the supplier of the quartz crystals and the user. The fact that the quartz crystal has no connecting wires requires special consideration, especially when determining the load resonance parameters. The basic measurement procedure corresponds to IEC 60444-5. The equivalent circuit model for quartz crystals is given in IEC 60122-1. When measuring quartz crystals in enclosures in the frequency range above several hundred MHz, it may be necessary to use an extended equivalent circuit. Depending on the design of the SMD enclosure, the results of measurements with and without grounding may differ when measuring load resonance parameters. If the quartz crystal is grounded in the application, the operating frequency can depend on the orientation of the quartz crystal in the circuit. It is therefore advisable to use the orientation mark on the quartz crystal (for example, pad 1) when correlating the operating frequency in the oscillator circuit with the load resonance measurement according to IEC 60444-5. The responsible committee is DKE/K 642 "Piezoelektrische Bauteile zur Frequenzstabilisierung und -selektion" ("Piezoelectric and dielectric devices for frequency control and selection") of the DKE (German Commission for Electrical, Electronic and Information Technologies) at DIN and VDE.