Hi,
I want to use EPC90150 for:
1.input voltage 34 to 185VDC.
2.output current 50A.
3.Output voltage 30.5 to 34vdc.
1.which controller buck to use?
2.How to reduce the heat from the board?
PLS advise?
Thank you.
Ilan Mazuz
Hello Ilan,
not clear if you need isolation, I’m assuming no isolation.
EPC90150 can be used as a building block or as a starting point for a new design.
Since max input voltage is 160V and max current is lower (up to about 25 A with heatsink and 10A without heatsink), it is not fulfilling the specs of the converter.
Higher current can be reached by using 2 or more phases in parallel.
185 VDC maximum might be ok if it is a transient/temporary condition (can happen but not all of the time). If it is a continuous operation then there is too little margin.
EPC2307 transient ratings are 240V, so extra care must be taken in the layout to minimize power loop inductance and reduce the overshoot as much as possible, eventually trading off with switching speed (higher value gate turn on resistors). The setup in EPC90150 achieves about 15% overshoot, which seems to show that temporary operation at 185V might be possible. Also all the components are rated above 200V (650V gate driver, 500V capacitors, …).
Summarizing:
- EPC2307 + NCP51820 is good for this application but heatsinking will be a challenge above about 15A per phase, so at least 3 phases would be needed. Switching frequency of 200 kHz looks possible. A stronger gate driver is possible (i.e. 2EDF7275K/2EDF7235K, MP18871), but the losses reduction would be small.
- In general, parallel FETs is possible but will increase a little the switching losses, due to layout tradeoffs. Also a stronger driver would be needed. Up to 2 FETs in parallel works reasonably good. If possible, use the multiphase approach. One good option might be 2 phases with 2 parallel devices each.
- Any buck converter controller which is cascadable to implement multiphase, or it is already multiphase, can work. i.e. ISL81806. It needs to be used to provide PWM signal to the high voltage gate driver.
- As said, 25 A for each EPC90150 will require the heatsink installed, the 17.8W/mK TIM (t-Global P/N: TG-A1780 X 0.5 mm) and a lot of airflow. The heatsink is not coming with the evalboard. Attached are the drawings, which can be ordered on PCBWay, either in copper or aluminum (we used copper for testing the evalboard).
AC1001_Rev1_0_EPC9000series_3DHeatspreader.step (113.2 KB)
AC1001_Rev1_0_MechanicalDrawing.pdf (235.9 KB)