Ripple Current Failure in Radial Electrolytic Capacitors
SUNTAN TECHNOLOGY COMPANY LIMITED · ALL KINDS OF CAPACITORS
Ripple current failure in electrolytic capacitors originates from internal heating caused by AC ripple superimposed on DC bias. Ripple heating accelerates electrolyte evaporation, increases ESR drift, and reduces effective capacitance. When internal heating combines with elevated ambient temperature, service life decreases faster than predictions based only on rated voltage or ambient rating.
System-Level Reliability Issue in SMPS and LED Drivers
Radial aluminum electrolytic capacitors in output filters experience continuous ripple stress. In SMPS topologies operating above 50kHz, RMS ripple current can exceed thermal design assumptions. In LED drivers, enclosed fixtures create high ambient conditions, further elevating capacitor core temperature.
Typical field symptoms include ESR rise, capacitance drop, ripple voltage increase, LED flicker, and output instability. These failures are thermal wear-out mechanisms rather than dielectric breakdown.
Electrothermal Mechanism of Ripple Heating
P = Iripple2 × ESR
Ripple current generates heat internally in the electrolyte and foil structure. Poor thermal dissipation causes localized temperature rise. Elevated core temperature accelerates electrolyte loss and oxide layer degradation, increasing ESR, which in turn increases ripple heating in a feedback loop.
Lifetime Impact Under Combined Stress
Temperature acceleration models show lifetime approximately halves for every 10°C rise. Ripple-induced core heating adds to ambient temperature, effectively pushing capacitors toward their endurance limits. Continuous operation environments such as LED luminaires and industrial power supplies show highest vulnerability.
Engineering Selection Criteria for Ripple Environments
| Parameter | Design Consideration | Selection Impact |
|---|---|---|
| Ripple Current RMS | Measured at operating frequency | Defines thermal stress level |
| PCB Thermal Zone | Distance from MOSFETs / diodes | Affects core temperature rise |
| Operating Hours | Continuous vs intermittent | Determines endurance requirement |
| Ambient Temperature | Fixture enclosure / airflow | Lifetime acceleration factor |
Series Comparison for Upgrade Without PCB Redesign
| Series | Endurance | Ripple Handling | Typical Use |
|---|---|---|---|
| TS14 / TS13DB | 105°C standard | General ripple | Control boards |
| TS13D2 / D4 / D8 / D9 | 5000–10000h | High ripple + high temp | LED drivers |
| TS13DI / D6 | Low impedance | High frequency ripple | SMPS outputs |
| TS13DL / D1 | Low leakage | Stable ESR | Precision circuits |
| TS13DM | Stable ESR | Audio ripple smoothing | Audio networks |
Environment-Based Selection Strategy
Reliable operation requires selecting capacitors based on combined ripple and temperature conditions rather than voltage rating alone.
For specification comparison based on ripple and temperature conditions, refer to official radial electrolytic capacitor specifications.





