SLVSBD1B December 2012 – August 2025 TPS65175
PRODUCTION DATA
The buck 1 operates in either continuous conduction mode (CCM) or discontinuous conduction mode (DCM), depending on the load current. The switch node waveforms for CCM and DCM operation are shown in Figure 6-5 and Figure 6-6. Note that the ringing seen during DCM operation (at light load) occurs because of parasitic capacitance in the PCB layout and is normal for DCM operation. There is very little energy contained in the ringing waveform and it does not significantly affect EMI performance.
The buck converter uses a skip mode to regulate VCC at very low load currents. This mode allows the converter to maintain its output at the required voltage while still meeting the requirement of a minimum on time. During skip mode, the buck converter switches for a few cycles, then stops switching for a few cycles, and then starts switching again and so on, for as long as the output current is below the skip mode threshold. Output voltage ripple can be a little higher during skip mode.