OPA549: OPA549

Hi,

You are absolutely correct, I often hear this called a "bridge tied load".

Here is TIDR182 which uses the smaller OPA569 for this function, but you can see that the implementation is very intuitive to what you would expect to see:

One thing to consider, I would be sure to include the external protection diodes (D1-D4). Servos can be reactive enough to cause voltage spiking from the starting and stopping of the rotor. 

Please let me know if you have any questions on the design of a circuit like this. 

Thanks,

Jacob

Hi Jacob,

My other problem is current. I need 8A current for my motor. But OPA569 supplies max 2A current. For this reason i could not use OPA569 in my circuit. 

Hey M. Bulent KAYA

Correct, we should consider adapting the configuration which the OPA569 is in, and swap in the OPA549. This should help realize the desired solution.

Do we know the impedance of the servo motor coil?

Thanks,

Jacob

Hi Jacob,

I don't know the impedance of the motor. But this week, i can measure the resistance.

Regards

M. Bulent KAYA

No problem,

I ask, because knowing the impedance will allow us to understand if we need significant excitation voltage to drive the motor. The bridge tied load certainly has some advantages. 

looking forward to seeing the coil data in the future. 

Thanks,

Jacob

Hi Jacob,

By the way, how can i calculate impedance of the motor?

M. Bulent KAYA

Hi,

We can measure this with an LCR meter. 

Alternatively, you could just measure DCR with a multimeter, but it would be nice to know inductance as well if possible. 

It is possible to make a quick measurement with a scope and Fgen to back calculate inductance. 

Thanks,

Jacob