Using a Charging Switch pfet for Solar Garden Light

Status
Not open for further replies.
Everyone is probably wore out about this subject, but here goes. Does using a pfet like a Si5855CDC make sense as a high side switch for a solar garden light? May have overlooked something here, so just asking before stocking up.

It includes a handy integrated schottky diode. It has a very low Vgs saturation voltage (1V max), which makes using the solar cell as the light sensor seem feasible. The Rdson of this pfet is < 0.2Ω, much lower than a small signal fet which can be from 1-10Ω. And, the cost is about $0.20.

Looking at other solutions, in low quantities, seems to put them in a $0.50-0.60 range.
1)Ldr, pfet, schottky diode
2)Photodiode, comparator, pfet, schottky diode
3)Pic10f204, schottky diode
 
The Vgs must be at least 1.8V for it to have a max resistance of 0.222 ohms.
A graph shows a "typical" Mosfet conducting about 250mA but you cannot buy a "typical" one.
With a Vgs of only 1V (its max threshold voltage) then some of these Mosfets conduct only 0.25mA.
 
Status
Not open for further replies.
Cookies are required to use this site. You must accept them to continue using the site. Learn more…