I'm trying to design a board that needs multiple voltages, and I've settled on some of TI's PTx series, since it seems that they're going to be pretty straightforward to implement. My current design has three supplies:
PTH08000W: 3.3V, with two MSP430s, GPS, magnetometer, gyro, and bluetooth module (<200mA)
PTH08000W: 5V, powering two remote encoders, one digital, and one analog (<50mA)
PTR08060W: 5.5V, powering two servos and an R/C receiver, drawing up to 3A at stall.
All of these will be pulled from the same 7.4V lithium battery, which brings me to my question. The datasheets for each of these supplies are very specific about what the capacitances should be on input and output. I'd love a little advice on what to use for the input capacitors, since there will be three supplies in parallel. Should I use a single larger capacitor (~220uF?) or put 100uFs as close to the input pins as possible?
Any advice is welcome, up to and including recommendations for the capacitors themselves- or even advice on the output capacitors for the specific loads mentioned.
Thanks,
Ben Stiles
NCSU grad student
Advanced Diagnosis and Controls Lab