I am trying to connect the output of a Digitally Programmable Step-Up Boost Converter (TPS61045) with a capacitor through a switch. Basically when the boost converter turns on it turns on at the median value. So I need to turn on the boost converter, send commands to lower the voltage to the minimum voltage (~3.6V). And then turn on the switch to connect the boost converter output to the capacitor to charge it. Then I ramp up the voltage of the boost converter to 19V. The purpose of this is to reduce the in rush current on the battery powering the boost converter by ramping the voltage in 64 steps. I'm also looking for a load switch to then discharge the capacitor onto a resistor after the capacitor is fully ramped to 19V.
Does anyone have any ideas of what switches to use for this application? I was looking at integrated load switches but tried using one (FDC6326L) and it wasnt working well.
I want to control the load switch with an arduino 3.3V logic level.
I was working with Power Relays for a bit but want to move towards FETs.
Thanks,
EDIT: I'm using 4 100uF multilayer ceramic caps that reduce by about 35% in capacitence when charged to 19V
Best Answer
For something like this, I would typically not use a programmable swich and just use a simple high side FET switch. On high side switches where the the power rail is significantly higher than the switching logic rail, you will need a pullup and an extra transistor to handle the switching function. The reason is because the logic level at the gate won't be high enough to cut off current to the high side FET and it will always be at least slightly on. Here's a typical configuration although you can replace the BJT with a FET as well.