I make a small solar energy harvester. I'm searching for the type of diode with lowest drop voltage. Any suggestion for the type of diode for me ?
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Most diodes will be better than 1N4148. Diodes for higher current will usually have less voltage drop at lower current. As Andy says, Schottky diodes will have lowest voltage drop. At about 200 mA voltage drops for common diodes are (from various datasheets):
DIODE Vdrop @ 200 mA Diode type 1N4148 1.0 Signal 1N4007 0.8 General rectifier (1A) 1N5408 0.6 General rectifier (3A) 1N5817 0.25 Schottky (1A) 1N5820 0.2 Schottky (3A)
You can try something like the 1N5817 Schottky diode, but note that lower drop goes hand-in-glove with higher reverse leakage (particularly egregious at higher temperatures).
For harvesting low voltage, you might want to consider the ideal diode using 1 FET , 2R’s and an IC or buy the board online.
Or if the cost justifies a better solution, this energy harvesting IC BQ25505 which specs include :
– Ultra-Low Quiescent Current of 325 nA.
– Input Voltage Regulation Prevents Collapsing High-Impedance Input Sources
Firstly you should post a quick schematic of what you're working with. Schottky diodes are the kind with the lowest voltage drop. But your common models will still drop around 200mV.
There are ways to achieve the same result as using a diode, without the voltage drop. But it's more complicated and would depend on your design.
For solar energy harvesting though, you should be fine with a single Schottky between your panel and the rest of your design. Something like a 30V/3A would work with your average panel and have a pretty low voltage drop. Of course that all depends on what panel(s) you are using and what is connected to them...
If you are just using the diodes to mux two power sources then you can use an ideal diode chip.
They typically consume micro-amps of current. The forward voltage drop is usually only a few mV.