johnsmith1212 Posted February 8, 2018 Report Share Posted February 8, 2018 hello, I am stuck with a dilemma which might or might not have a simple solution. more: giá chung cư 17 phạm hùng I have a psu supplying 46Vdc unofrtunately i need to step this down to several different voltages. 1) 14 to 20Vdc (best would be 16Vdc) to power a micro mainboard power supply thingy, using approx 100W 2) 12Vdc form as well a led strip, a fan, temperature sensors (LM35 i believe) and arduino atmega 2560 board 3) 5Vdc so i was thinking (maybe wrongly) to use a couple of 100W resistors in series (5KΩ - 5KΩ - 5KΩ&2KΩ - 2KΩ) and use it as voltage dividers. if I calculate correctly this should give me 2/19 * 46 = 4.8Vdc 5/19 * 46 = 12.1Vdc (2 times) 7/19 * 46 = 16.9Vdc more: giá căn hộ iris garden trần hữu dực so going from the assumption that all this above is correct, i started to wunder if the is a problem when there is a big difference in power consumption between the different voltages. as the 16.9Vdc "rail" would use approx 90-95 Watt (also pushing to the limits of the resistors used) and approx 1A for the 5Vdc "rail" if this is not a usable option.. is there an other way to do this correctly? i have a step down board but this one has a max. input power limit of 40Vdc, en even though i swapped the capacitors to larger once i believe that the actually limit is defined by (an) other component on the PCB, which i would blow up. specially as it would be on 24/7 also voltage regulators can supply this power.. any advice would be highly appreciated. more: giá căn hộ park residence lê văn lương ps: i understand i faultly use term rail here., and no a different PSU is not an option! Quote Link to comment Share on other sites More sharing options...
HarryA Posted February 9, 2018 Report Share Posted February 9, 2018 How about 3 terminal adjustable voltage regulators? see for example: https://www.mouser.com/ProductDetail/ON-Semiconductor-Fairchild/LM317AHVT?qs=%2fha2pyFadugRpOCsw7uJG%2fYkcWjLe5SQfHkipQZSRvGAuHf8Q8Z20lpgQCwyK1vllMxUP7WNhWIGj0RAnAK1dQ%3d%3d 60 volts max and 1.5 amperes. Poke around at Mouser for higher current ones also. There are filters on their site that are helpful. Quote Link to comment Share on other sites More sharing options...
admin Posted February 13, 2018 Report Share Posted February 13, 2018 He will need something more powerful at least for the 16Vdc rail. Something like the LT3845A, which has 60V input voltage and 15A output current may work for this application. Datasheet: https://www.mouser.com/ds/2/609/3845afa-1270855.pdf Quote Link to comment Share on other sites More sharing options...
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