Nature of transient currents and voltages in the power chain for a Highly Segmented Fast Detector run by Low Voltage Power Supply

Supplying power at low voltage to the front-end electronics of very fast and highly segmented detectors, typical in the experiments at the Large Hadron Collider, involves several issues, including transient currents and voltages. This study investigates a power chain that involves long cables, DC-DC converters, and input filters. Due to the presence of a common ground close to the input of the DC-DC converter, the power chain can run with a lower value of the input supply. It is seen that the capacitor in the input filter plays a significant role in the process of voltage growth at the input of the DC-DC converter. The effects of the ramp during turning ON and OFF the input supply have been studied thoroughly. It is observed that the voltage/current spikes are reduced due to the application of the ramp. It is also observed that the current/voltage, both at the input and the output of the DC-DC converter, goes through some intermediate oscillations due to the existence of threshold voltage for the converters. The choice of the ramp is critical in reducing spikes and should be incorporated into the power supply.