SN EN 60444-3 : 1997

Committees responsible
National foreword
Method
1 Scope
2 Co compensation circuit
    2.1 Electrical specifications
    2.2 Mechanical specification
3 Crystal unit parameters with and without Co
    compensation
    3.1 Series resonance frequency fs and resonance
          frequency fr
    3.2 Motional resistance Rl and resonance resistance
          Rr
    3.3 Motional capacitance Cl and motional inductance
          Ll
4 Test circuit
    4.1 The pi-network
    4.2 Accessories of the pi-network
    4.3 Associated equipment
    4.4 Compensation circuit
5 Method of measurement
    5.1 Initial calibration of the pi-network
    5.2 Tuning of the compensation circuit
    5.3 Frequency and resistance measurement
    5.4 Evaluation of the motional capitance Cl and
          motional inductance Ll
Appendices
A Analysis of the difference of f, R, Cl and Ll as result
    of measurement methods with and without compensation of Co
B Additional information on accuracy
C Additional information on circuit components given in
    Figures 4a) and 4b)
Table
A1 Typical values for parameters of oscillator crystal units
    and the calculated theoretical differences between
    parameters increased with and without compensation
Figures
1 Equivalent circuit of a crystal unit with compensation
    of Co
2 Impedance diagram of a crystal unit without compensation
    of parallel capacitance Co
3 Impedance diagram of a crystal unit when Co is
    compensated with a properly tuned compensation network
    according to Figure 1
4a Simplified diagram of the pi-network with electrical
    adjustment of Co compensation
4b Simplified diagram of the pi-network with mechanical
    adjustment of Co compensation
5 Test circuit