good evening, 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. Could someone give me their opinions on the motor drivers that I found to replace the l293d drivers? I would greatly appreciate it.
Motor:
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
Lipo
Item Name: Lipo Battery
Capacity: 3.7V 150mah
Length of output line: 30mm
Playing time:6-7min
Charging Time : About 20 min
and planning to use this motor driver
DRV8838 Dual Motor
Motor driver: DRV8838
Motor channels: 1
Minimum operating voltage: 0 V
Maximum operating voltage: 11 V
Continuous output current per channel: 1.7 A2
Peak output current per channel: 1.8 A
Maximum PWM frequency: 250 kHz
Minimum logic voltage: 1.8 V
Maximum logic voltage: 7 V
Reverse voltage protection?: Y
or this other one:
DRV8835 Dual Motor
Motor driver: DRV8835
Motor channels: 2
Minimum operating voltage: 0 V
Maximum operating voltage: 11 V
Continuous output current per channel: 1.2 A2
Peak output current per channel: 1.5 A
Continuous paralleled output current: 2.4 A2
Maximum PWM frequency: 250 kHz
Minimum logic voltage: 2 V
Maximum logic voltage: 7 V
Reverse voltage protection?: Y
H bridges shouldn't be necessary for drone motors, they always spin the same way (well there may be
some exceptions to this for exotic devices maybe).
So H-bridge isn't needed, just a transistor + freewheel diode.
Your motor specs say 0.9 ohm and 240mAh stall current, which makes no sense at all.
The stall current is Vsupply / resistance = several amps in fact. This is to be expected as
these motors have to generate significant power for their size. The stall current won't be
pulled for long as the startup is very rapid with tiny motors.
Is your supply 3.7V? If so then yes you need low voltage logic MOSFETs, or a high performance
BJT like the phenomenal ZTX851 (very low saturation voltage - will need plenty of base
current though, so 150 ohm base resistors). The ZTX851 is in a tiny e-line package which will
help with the mass budget. Any small diode with reasonable pulse current rating will make a
suitable free-wheel diode.
Those have +/-8V max Vgs, the datasheet I found never mentions 2.35V
The max drain current is 2A at 70degC, so they aren't really beefy enough to be sure
of reliable operation - go for more like 5 to 20A rating (you never ever want to be
close to max continuous current with a MOSFET, that means it will be screaming hot).
eBay is not the best source for reliable components, be aware, and the choice is very limited
compared to electronics distributors.
