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Author Topic: L6235 THREE PHASE motor driver stall current  (Read 2444 times)

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Offline Jak24Topic starter

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L6235 THREE PHASE motor driver stall current
« on: November 01, 2010, 04:16:14 AM »
Hi!

I was reading the datasheet of the L6235 and saw the diagram of max load current on page 21.
But the datasheet says nothing about a stall current, my motor would have a 1,7 A max load current
which the chip can handle, but the stall current of my motor would be almost 10 A ,
which i don't know if the chip could handle.
Does anyone know if it could handle it?

Thanks

Regards
Jak24

Offline waltr

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Re: L6235 THREE PHASE motor driver stall current
« Reply #1 on: November 01, 2010, 07:35:20 AM »
No, unless there is a current limiting provision in the chip or you provide a circuit that limits the motor current.

Offline Soeren

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Re: L6235 THREE PHASE motor driver stall current
« Reply #2 on: November 03, 2010, 09:53:53 AM »
Hi,

I was reading the datasheet of the L6235 and saw the diagram of max load current on page 21.
But the datasheet says nothing about a stall current, my motor would have a 1,7 A max load current
which the chip can handle, but the stall current of my motor would be almost 10 A ,
which i don't know if the chip could handle.
Does anyone know if it could handle it?
Sorry, but the link to the datasheet is not working ;)
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
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Offline Jak24Topic starter

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Offline knossos

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Re: L6235 THREE PHASE motor driver stall current
« Reply #4 on: November 06, 2010, 08:58:59 PM »
It looks like the max current for the L6235 is 5.6 A peak.  So if your motors have a 10 A stall current I would say no.  Also the link you posted is an application note.  Here is the L6235 datasheet.
"Never regret thy fall,
O Icarus of the fearless flight
For the greatest tragedy of them all
Is never to feel the burning light."
 
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Offline Soeren

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Re: L6235 THREE PHASE motor driver stall current
« Reply #5 on: November 06, 2010, 11:34:07 PM »
Hi,

According to the data sheet linked by knossos it says 2.8A max each output (I assume he just added them together to get to the 5.6A).
But, it shouldn't matter... Read p. 8 under the heading Logic Inputs (second para.):
Quote
Pin EN (enable) may be used to implement Overcurrent and Thermal protection by connecting it to the open collector DIAG output [...]
Just follow the description in the data sheet and it should work, protecting the motor against meltdown when stalled as well.
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline Jak24Topic starter

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Re: L6235 THREE PHASE motor driver stall current
« Reply #6 on: December 02, 2010, 08:39:20 AM »
Hi

I recently got around to get the items required to build the controller,
i bought an l6235 and a brushless motor(it was one used for model airplanes)
but i have doubt that the l6235 can handle the stall current of the motor i currently have,
i don't know the exact stall current but i figure it's pretty high because the max continues current is 18A
and even if i cut the power down with PWM the stall current would still be the same,
also if i connected pin ENABLE with DIAG output
Quote
Pin EN (enable) may be used to implement Overcurrent and Thermal protection by connecting it to the open collector DIAG output [...]
i doubt that small IC can handle 18 + amps
what can i do so i can test the motor without blowing up IC.

Regards

Jak24

Offline knossos

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Re: L6235 THREE PHASE motor driver stall current
« Reply #7 on: December 02, 2010, 02:57:29 PM »
According to the data sheet linked by knossos it says 2.8A max each output (I assume he just added them together to get to the 5.6A).

I was referring to this line here:
Quote
5.6A OUTPUT PEAK CURRENT (2.8A DC)
which is for both outputs.  I should have been more clear about that.

i doubt that small IC can handle 18 + amps
what can i do so i can test the motor without blowing up IC.

The section Soeren pointed out gives the information you need.  It can protect itself and the motor from overcurrents.  You need to connect an external resistor and capacitor.  The information for resistor and cap selection is also in the documents.   

(This is all pretty much paraphrased from the appropriate sections:)
The Delay Time (tDELAY) before overcurrent protection kicks in is determined by this capacitor (CEN ).
The cap also provides noise protection for the enable (EN) signal. The cap should be as big as possible without making the Delay Time too long.

The resistor (REN) value determines how long the circuit should stay disabled (tDISABLE).

The datasheet recommends a 100KΩ resistor and 5.6nF cap.  This would give you a 200μs Disable Time.

If you need a longer disable time, or a shorter delay before disabling, you can look at figures 19 and 20 to select more appropriate values.  For example (values chosen just because they line up neatly on the charts) a 3 nF cap and a 220KΩ resistor would give about a 300μs disable time and about a 0.9μs delay before disabling the circuit.
"Never regret thy fall,
O Icarus of the fearless flight
For the greatest tragedy of them all
Is never to feel the burning light."
 
— Oscar Wilde

 


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