1 Introduction

Enhanced HotRod QFN is the latest advancement in semiconductor packaging which enables the industry's smallest 4-A, 36-V step-down converter. Figure 1-1 shows the semiconductor packaging technology evolution for high-power density step-down converters. The LM43603 was developed in a leaded HTSSOP package which uses a ground DAP for optimal thermal dissipation through the bottom side of the package. Second, the LMR23630 was released in a standard QFN package to eliminate the external leads while still having a thermal DAP. Consequently, the LMR23630 package size decreased by 73% compared to the previous generation converter. Third, the flip-chip on lead-frame (FCOL) technology has further improved the package-to-die ratio and removed package wirebonds connecting die to lead-frame to provide best-in-class noise performance. The Enhanced HotRod QFN package leverages the noise improvements of the FCOL package (Section 2) and the thermal advantages of the standard QFN package (Section 4). Figure 1-2 highlights the enhancements from FCOL and standard QFN packages to 'Enhanced' QFN. The latest TI part developed with Enhanced HotRod QFN package technology is the LM60440 device. It has a 4-A output current capability in an ultra-small 3-mm × 2mm package.