Hello
I am building a small drone. I got those motors
and smd mosfets
Here is simple circuit I use to test it.
What I found is that motor spins pretty slow with SMD mosfet I got. I assume that I got the wrong one. I tested the motor with https://www.amazon.com/gp/product/B071Z98SRG/ref=oh_aui_search_detailpage?ie=UTF8&psc=1 and it works super fast.
Did I pick wrong smd mosfet? could anybody suggest right smd mosfet for motors I have?
Show us a good schematic of your circuit.
Show us a good image of your wiring.
Posting images:
https://forum.arduino.cc/index.php?topic=519037.0
What is the resistance and voltage rating of the motor?
RFP30N06LE is a much better choice.
AOD514/AOI514/AOY514 versions are good for logic level N channel MOS FETs.
You got signal MOSFETs, not power MOSFETs!!!
Is this running at 3.7V ? You'l need a logic-level MOSFET designed for 3.3V logic, not just 5V...
For instance: http://uk.farnell.com/infineon/bsl802snh6327xtsa1/mosfet-aec-q101-n-ch-20v-tsop/dp/2781056
Which has a low Rds(on) of 22 milliohms at 2.5V gate drive.
Yes, the motor runs on 3.7V. Does this mosfet have to transistors inside? why does it have 6 pins?
Did you look at the "Technical Datasheet" on that page.
That .pdf shows the drain connected to four pins (thermal dissipation).
Leo..
Looking at the specifications of the motor:
No Load Current: 280mA max
Stall Current: 10,570mA
The FET is rated at 115mA.
Need I say more?
yes please
JohnLincoln:
Looking at the specifications of the motor:No Load Current: 280mA max
Stall Current: 10,570mAThe FET is rated at 115mA.
Need I say more?
yes please
Such a low-power FET will be internally melted if it ever handles even the minimum motor current.
Secondly running a FET near its max current requires good heatsinking, and usually
is not done - you typically run at 10--20% or so of max, since you don't want the extra
cost of a heatsink nor the wasted heat to dispose of. The current rating is typically just
the maximum heat dissipation rating in disguise. Not a useful parameter in fact.
You pick a MOSFET from its on-resistance and your requirement for maximum power dissipation.
If you want, say, a max of 0.5W dissipation for a load of 5A, your MOSFET should have an on-resistance
of 0.5 / (5*5) = 0.02 ohms or less. Not 7.5 ohm like the 2N7002
power = I-squared-R
A 7.5 ohm MOSFET at 5A would be about 200W dissipation (except it wouldn't as the voltage drop
across it is more than Vgs, which isn't tenable)
That makes sense. Thank you for help and patience.
