SNVS609K December 2008 – June 2022 LM25088 , LM25088-Q1
PRODUCTION DATA
Excessive ringing and spikes can cause erratic operation and couple spikes and noise to the output. Voltage spikes beyond the rating of the LM25088 or the re-circulating diode can damage these devices. A snubber network across the power diode reduces ringing and spikes at the switching node. Selecting the values for the snubber is best accomplished through empirical methods. First, make sure that the lead lengths for the snubber connections are very short. For the current levels typical for the LM25088, a resistor value between 3 Ω and 10 Ω should be adequate. As a rule of thumb, a snubber capacitor, which is 4 to 5 times, the junction capacitance of the Schottky diode reduces spikes adequately. Increasing the value of the snubber capacitor results in more damping, but also results in higher losses. The power dissipation of the resistor is independent of the resistance value as the resistor dissipates the energy stored by the snubber capacitor. The power dissipation of the resistor can be approximated as: