Electronics > Beginners
Switching power supply with small to high loads
Yaroooo:
I want to realize a circuit that allow to have a regulated voltage of 5v and be able to supply up to 1.3A .
I can't use a linear LDO cause a huge voltage drop on it, input may vary between 24 to 40v and with this current load isn't suitable.
On this board I've also a Micro that have a very small load current. Since my circuit may have only micro ON as well as all load ON (some LEDs in example), it should have an operating range between 1mA to 1.3A.
Looking at some datasheets, common switching regulators that allow to supply such current has good efficency above 300mA. Where i.e. LT8608 is too expensive.
Do you have advices or components usable to this porpuses? My idea was LM2501x series and TPS5414 , but they have efficency near to 0 at 1mA.
madires:
There are tons of buck converter ICs to choose from, but you won't find any with high efficiency at very low and high loads. Anyhow, a low efficiency at a load of few mA doesn't matter much because the losses are small too.
Yaroooo:
--- Quote from: madires on April 08, 2019, 03:23:56 pm ---Anyhow, a low efficiency at a load of few mA doesn't matter much because the losses are small too.
--- End quote ---
Thanks for your answer.
Are there alternatives in circuits methods to avoid this? Double power supply or double regulators? I'm asking piratical examples in common products.
SeanB:
If you atre doing a lot of LED's and they are going to draw a lot of power, ranging from all on to all off, then 2 separate power converters will work. Low power one to drive the microcontroller, and a separate one with an enable to do the LED drive voltage. When they are all off the power supply is switched off with the enable, otherwise you enable it. As an advantage you can choose LED drive voltage to have multiple series strings, if the LED's are always going to be on like that, and if so then you can also use LED driver converters to do both the drive and current control, and save on power converter and switches, using LED drivers with dimming and enable as needed.
David Hess:
Switching regulators which support burst mode operation can have good efficiency at high and low loads.
I would consider using separate converters for the control and power circuits.
24 to 40 volts down to 5 volts is quite a step. Consider using a boosted current buck converter with a tapped inductor to get a more reasonable duty cycle.
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