Since drive level is calculated by the following equation as described in drive level (1) , the temperature characteristics of the drive level are determined by the temperature characteristics of R_L and i.

DL (μW) = R_L (Ω)×i² (mA)
DL: drive level
R_L: load resonance resistance of crystal unit
i: Current value flowing through crystal unit (RMS value)

1. Temperature Characteristics in "R_L: load resonance resistance in crystal unit"
In operating temperature range specified in the specification sheets, R_L is almost the same.

2. Temperature characteristics of " i: Current value (RMS value) flowing through crystal unit"
The resistance temperature coefficient of the circuit board itself causes i to be slightly increased or decreased, but it is generally unchanged.

This means that drive level remains almost unchanged even if the temperature changes.