Hello,
We are switching the LM5113 at 13.56MHz in a Class D amplifier for inductive coupling at 4 to 9 V, 200-400 mA total amplifier + load consumption. I am not certain how much of this is being dissipated in the FETs and Gate Driver vs. how much makes it to the load. However, temperature measurements show that the vicinity of the gate driver is reaching ~ 75C. In our closed plastic enclosure with no air flow, the plastic surface directly above the gate driver is getting too hot (~60C, which is 20C higher than required in this application). To reduce the heating of the product in general, we want to either
(a) effectively sink this heat away from the gate driver to spread it out better (reducing the hot spot); or
(b) reduce power loss in the gate driver.
The second item will require sharing schematics and waveforms, which I am happy to do over email at your request.
The first item is a more general question: we do not have large copper polys on the board to sink heat away, nor any room to add copper. So, how can we heat sink the DSBGA and the nearby CSP packages of the FETs? We have tried adding a heatsink in contact with the opposite side of the board, but we do not know how to effectively (and safely) put a heat sink in thermal contact with these small packages. What do you recommend?
Thanks in advance for your time.
