1 Introduction

General power rails on TV scaler board in FHD LCD TV include 1.5 V rail for DDR chipset, 1.2 V for SoC chipset, 3.5 V for u-Com, 3.3 V for peripheral rails such as I²C pull up and the logic voltage of the audio amplifier and 5 V for HDMI, USB and HDD ports. In this application report, TPS5432 is used to generate 1.2 V rail for the core voltage of SoC chipset.

Because the TPS5432 is a 6 V, 3 A, low Iq, current mode, synchronous monolithic buck converter with integrated MOSFETs. The TPS5432 enables small designs by integrating the MOSFETs, implementing current mode control to reduce external component count, reducing inductor size by 700kHz switching frequency. SOIC-8 package with exposed thermal pad provides both thermally enhanced solution and easy to use.

In addition, the load release characteristics caused by SoC chipset during power off sequence is verified and it can trigger an unexpected OVTP (Overvoltage transition protection) and RCP (Reverse current protection) as well as. Furthermore, it results in generating a severe overshoot voltage on PH node.