RESEARCH
A complete 3D integration of power supply for non-isolated point-of-load applications extending up to 30 Watts (2006)
Year: 2006
Fig. 1. Photo of fully integrated POL on a 25 cent coin
The latest Point of Load (POL) technology developed at CPES uses novel packaging called "Stacked Power" that allows for low-voltage active devices to be embedded inside a ceramic layer of high thermal conductivity. This in turn frees up the top and bottom sides for the integration of other circuit parts. This vertical integration allows for layouts with low circuit parasitics so that efficient high-frequency operation can be realized. High operating frequency reduces the size of the passive components needed, thus increasing power density.
The stacked layers are made using Direct Bonded Copper (DBC) which integrates the thermal management. This eliminates the need for a heat sink and yet only very modest airflow is necessary. The passives are integrated with the active layer by means of Low-Temperature Co-fired Ceramic (LTCC). LTCC technology enables the integration of low-profile inductors with high current capabilities.
The Figure shows a single-phase 5V-1.2V module with combined active and LTCC passive layers that has been fabricated in CPES. It achieves 88% efficiency at 24A output current and 91% at 10A - all this with a very high power density of 260 W/in3 at a low duty cycle of 24%. This module's efficiency surpasses industry products available today and when taking all thermal management into account, has higher power density as well. Stacked Power integration achieves small size and high power handling capability while using little energy - which is something we can all appreciate.
