Evaluating Internal RC Oscillator Drift during Deep Power Down
Evaluating internal RC drift requires mapping temperature and voltage sags to expanded radio receive windows that drain battery reserves.
Temperature Drift
Meaning
Variations in the electrical or physical characteristics of a component that occur as the operating temperature changes can affect the stability and performance of an electronic system. The occurrence of temperature drift in the frequency-determining elements of an oscillator causes the system clock to accelerate or decelerate as the device warms up or cools down. This variation must be characterized and compensated for to ensure reliable operation across the specified temperature range.
Oscillator Deviation
The frequency of quartz crystals changes in a predictable manner as temperature varies, which can lead to communication failures if not corrected. This behavior requires the use of temperature-compensated oscillators in applications with strict frequency stability requirements.
Sensor Accuracy
Analog sensors also exhibit changes in their output values due to thermal variations in their internal materials and sensing elements. Applying a calibration offset in the firmware can correct these errors by using a temperature reading taken from a sensor located close to the primary transducer.
System Compensation
The implementation of compensation techniques allows the system to maintain its accuracy across a wide range of environmental conditions. These techniques include the use of lookup tables or polynomial equations that calculate the required correction factor based on the current temperature. Engineers must test the finished assembly in a thermal chamber to verify that the compensation algorithm correctly cancels the drift.
This testing is crucial for devices that are deployed in outdoor environments where temperature fluctuations can be extreme.