This week I tried out a new DC-DC converter, the RT8293BHGSP, for my singing pumpkin controller. The issue I had with the old converter was that it was pretty expensive to get a 100uH coil that was rated for 4 or 5 amps. The most recent spin of the board only has about a 1.5 amp coil on it. This new converter runs at a little over 1Mhz as opposed to ~300kHz for the old converter. As such it can use a much lower value coil (10uH) that can be obtained in the 4 to 5 amp range for a reasonable price and with a reasonable package size.
This tester board seemed to work pretty well. It got plenty warm pushing around 2 amps, so it may need a heat sink. Still I’m pleased to have a solution that lets me get all the way up to the 3 amp limit of the converter.
What are the input & output voltages? What’s the total cost on the board?
I haven’t properly worked up the total BOM cost just yet. But the switcher chip is 0.86, the 10uF caps are around 0.16, and the coil was probably a dollar. The max input voltage is 23V, while I run at 12 to 14V. My output is selected for 6V to power singing pumpkin servos. The max output current is 3A.