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.
Internal Resistance ESR
Meaning
An electrical parameter represents the total resistive losses within a capacitor, inductor or battery cell during alternating current operation. This internal resistance esr limits the ability of a decoupling capacitor to smooth out high-frequency voltage ripples on a microcontroller power rail. High values restrict the peak current delivery required by cellular transmitters during uplink bursts.
Thermal Dissipation
Power lost as heat is calculated by multiplying the square of the ripple current by this resistive value. A high internal resistance esr causes the component to run hot during heavy loads.
Measurement Frequency
The value of this parameter varies with the operating frequency and temperature of the circuit board. Capacitors are typically evaluated at one hundred kilohertz to match common switching regulator frequencies. Lower test frequencies often reveal higher resistive values due to dielectric losses.
Component Degradation
As electrolytic capacitors age, their internal electrolyte dries out, which leads to a dramatic rise in this resistive value. This deterioration degrades the transient response of the power supply and leads to system resets under load. In battery packs, rising internal resistance esr reduces the run time of smart devices and triggers premature low-voltage shutdown events.
Monitoring this value during qualification runs helps engineers select parts that can survive long-term field operations.