Orangutan x2 VNH3SP30 - power consumption on motor port?

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41

hi,
just wanted to tell you that i desolderd one CS2 resistor and it works perfectly now. the sensor is more sensible and i could find the exact definition of the amount of stalling torque i needed! thank you so much for this simple solution!

42

I’m very glad to hear it’s now working for you!

- Ben

43

hi ben,

i bought a second svp. unfortunately the sensitivity on both ports is too less, even if i knock out one sensor. can you tell me which resistor i should buy to get the sensitivity quadrupled? you said 0.1 Ohm, but what about the other specifications? (mW, …)

what would happen, if i knock out both resistors?

thanks again!

44

All of the motor driver current flows through those current-sense resistors, so knocking out both resistors would disable the motor driver. You should get an 0805 surface-mount resistor with a sufficient power rating. Power is given by I^2R, so if you need to be able to handle 1 A through a 0.1 Ohm current sense resistor, the resistor would need to be rated for at least 11*0.1 = 0.1 W.

The larger the resistor you use, the higher your sensitivity will be. However, larger current sense resistance also means more lost power, and a bigger voltage drop at high currents, so your motor will be seeing a lower voltage than you are supplying. I suggest you consider trying a 0.1 or 0.2 Ohm resistor.

- Ben

45

Hi Ben,
I tried to find some matching resistors, but there are some other parameters i am not sure about. Finally i found three which could fit. could you be so kind and have a look at them and tell me which one’s the best and why?

http://at.farnell.com/bourns/crl0805-jw-r100elf/resistor-metal-oxide-0-1ohm-0805/dp/1767845

http://at.farnell.com/bourns/crl0805-fw-r100elf/widerstand-0805-r1-1-0-125w/dp/2008297

http://at.farnell.com/te-connectivity-cgs/rl73k2ar10jtd/widerstand-rl73k-r10/dp/8867488

Thank you!

46

I would probably go with the 0.2 Ohm equivalent of:

at.farnell.com/bourns/crl0805-fw … dp/2008297

You can get 0.1 Ohms by using two 0.2 Ohm resistors in parallel, and if that doesn’t prove sensitive enough, you can knock one off to see what the sensitivity is like with a current-sense resistance of 0.2 Ohms.

Note that you should only use a current-sense resistance of 0.2 Ohms if you’re sure the corresponding motor driver current will never exceed 600 mA. You can go as high as 1.2 A when the CS resistance is 0.1 Ohms.

- Ben