| Electronics > Beginners |
| isolated dc/dc converter input capacitors and output ferrite beads |
| (1/1) |
| V_King:
Hello, I want to incorporate 3x isolated dc/dc converters to give me galvanic isolation and all required voltages for a small control board. I have two questions as follows: 1. For power inputs, the manufacturers recommends certain capacitor values, but if I have three DC/DC converters in parallel, do I put same value capacitor in front of each dc/dc converter, or do I put one same value or bigger cap? All manufacturers give max input/output capacitances, so I want to avoid instability issues. 2. Same for the power input fuse as above. Do I triple the current requirement, or put three fuses for each of the DC/DC converters 3. Finally, I've read application note from analog devices, recommending to use ferrite beads after dc/dc converter and LDO to reduce the ripple and noise. Application note says the ferrite bead impedance @ freq. must be matched to the dc/dc converter switching frequency. But all dc/dc converters I find are around 100kHz and ferrite beads rated at 25MHz and above. have I misread something, or am I looking at the wrong ferrite beads? Or in real life, a few paralleled caps should do the trick? The power supplies are going into powering op-ams and ADC analogue side. Thanks |
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