Tuesday, 5 July 2016

driver - Hot MOSFET DC-DC Boost Converter


What: I'm designing a DC-DC Boost converter for a solar panel maxmimum-power-point-tracker (MPPT).



Setup: I'm using a TPS2819 MOSFET driver connected to a FQD16N25C N-MOSFET. The TPS2819 is driven by a 5V PWM source at ~500Hz. With the duty cycle set to roughly 50%.


Problem: The FQD16N25C gets very hot with a 48ohm resistive load on the output.


Shown below is the schematic of the boost converter stage:


enter image description here


A DC power supply was connected to input (Vsolar and GND). A 48ohm resistor was placed across the output (Vbatt and GND)


Shown here is the Vds wave form of the mosfet. With an input voltage of 2.64V, the current draw is 1.687A


Vgs waveform


From what I've read about N enhancement MOSFETs, what may be happening is that the MOSFET is operating in the linear triode region as opposed to full saturation. However, I'm not exactly sure how to solve this




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