I'm building a minidrone based on an eachine using the same components as the original but instead controlling it with an arduino nano, a bluetooth module and a 6 axis gyroscope. I had available 2 l293d's to drive the motors but the motors barely lift the drone. I was told the problem was that l293d is terrible option for lower voltage applications and I need to use low level mosfets(low Vgs) instead(also drones don't need to reverse the voltage of the motors).I'm planning to replace the H bridges with Si2302ds mosfets and shottky diodes.

Here are the respective datasheets :

SI2302DS https://www.vishay.com/docs/70628/70628.pdf

1N5819 https://www.diodes.com/assets/Datasheets/ds23001.pdf

and this is what I found about the motors :

1.Operating condition Rated voltage 3.4V DC Direction of rotation CW and CCW Operating voltage range DC2.0--4.5V DC perating temperature range -10-50°C Motor position all position

2.Mearsuring condition Motor position horizontal or vertical Power supply regulated DC power supply assuring unquestionable measuring regulated DC power supply assuring unquestionable measuring 10-30°C 30-95% If the judgment is questionable,Measurent is to be made based on JIS Standard Testing Condition(20+2°C,65+5% ) Direction of rotation viewed from output shaft side

3.Electrical characteristics Items Specification Standard value No Load speed 67000rpm±15% 67000 rpm No Load current 200mA max 180mA Starting voltage 0.8V max 0.5V DC Stall current 240mA±5% 240mA Terminal resistance 0.9Ω ±5% 0.9Ω Insulation resistance 10MΩ min AT 250V DC between motor terminal and case

I've been told that the stalling current given is wrong since a 0.9ohm motor resistance results in a 3.7 / 0.9 = ~4Amp stall current (not 240mA).

I will also power the drone with the same battery that the eachine uses:

Battery Power:3.7V 260MAH 45C

My main concern is if I'm choosing the right mosfet for this project. I'll appreciate any suggestions.


1 Answer 1


0.8V start voltage max. implies low duty cycle PWM for starting

0.5V DC Stall current 240mA±5 means DCR=500mV/240mA= 2 Ω

You must regulate the PWM for a soft start current of 240mA.

The MOSFETs only need to be < 100 mΩ to add 5% loss compared with 2 Ω in motor.

  • \$\begingroup\$ this is what I found Rds On - Drain-Source Resistance: 72 mOhms. I'm guessing that should do it ? should I consider any other feature? Thanks for your time. \$\endgroup\$
    – pekoms
    Commented Nov 7, 2017 at 2:55

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