RCinFLA
Well-Known Member
"how do i make 100 uH coil for this circuit ? actually i want to run a lcd screen (2 amp) with this power supply instead of direct 70 amp battery in order to protect lcd from any mishap or power fluctuations.
please guide me as i am newbie in this...
further more how can i measure inductance so i can calculate at my own if i need some other numbers, as normal multimeter can't help.
"
You are likely going to have trouble if you intend to operate it over that wide an input voltage range with the single fixed inductor value. With load current variation and that wide an input to output voltage range the switching PWM min and max duty cycle will likely be exceeded.
You would need a pulse skipping or PFM design to handle that large an input range.
The part is designed to work over a narrower input voltage range. You have to select the value of coil based on the input to output voltage ratio.
Using salvaged cores is pot luck. Small signal inductance value does not predict how the coil reacts when subjected to high bias current or core losses at given run frequency. Most salvaged torroid cores are for AC line filtering which are not suitable for a high freq buck or boost switcher coil.
The site: Ferrite Data : CWS ByteMark, largest supplier of toroids, ferrite cores, iron powder cores, MPP cores and RF cores
has the design info needed to make a torroid inductor. You will need 5 to 6 amp peak current capability on the core. At 50 kHz this will likely be approximately a little less then a 1 inch diameter core but depends on your final inductance value.
please guide me as i am newbie in this...
further more how can i measure inductance so i can calculate at my own if i need some other numbers, as normal multimeter can't help.
"
You are likely going to have trouble if you intend to operate it over that wide an input voltage range with the single fixed inductor value. With load current variation and that wide an input to output voltage range the switching PWM min and max duty cycle will likely be exceeded.
You would need a pulse skipping or PFM design to handle that large an input range.
The part is designed to work over a narrower input voltage range. You have to select the value of coil based on the input to output voltage ratio.
Using salvaged cores is pot luck. Small signal inductance value does not predict how the coil reacts when subjected to high bias current or core losses at given run frequency. Most salvaged torroid cores are for AC line filtering which are not suitable for a high freq buck or boost switcher coil.
The site: Ferrite Data : CWS ByteMark, largest supplier of toroids, ferrite cores, iron powder cores, MPP cores and RF cores
has the design info needed to make a torroid inductor. You will need 5 to 6 amp peak current capability on the core. At 50 kHz this will likely be approximately a little less then a 1 inch diameter core but depends on your final inductance value.
Last edited:
