TMC5160A-WA hardware configuration for control through only SPI

Does encoder output from motor is necessary to connect to encoder pins of TMC5160 to operate using spi interface?or leave floating?

An encoder is optional. It is not required for motor operation. You can leave ENCA and ENCB unconnected. As ENCN does not have an internal resistor, optimally provide a pull up or pull down resistor. 

thanks for inputs. currently we are doing layout design for the TMC5160 taking evk files as reference....other than this any other layout reference files can you suggest for guidlines of layout design?....we are designing a medical product ...

Hi Savi,

we do not have more layout examples. Please make sure that you do a low inductive and compact layout using a minimum of 4 PCB layers with one layer dedicated as GND plane. I would also suggest to add LC filters with <50MHz bandwidth close to the PCB connectors, both for the motor outputs and for the power supply. 

I would like to also point you to our latest device, the TMC5262. It is similar to the TMC5160 concerning general features, but has an internal power stage for up to 4.25A RMS current. A main benefit with an integrated power stage is, that EMI conformance is easier to reach, as the internal power stage is very compact and has near zero parasitic inductance in the interconnections. The TMC5262 brings further benefits with regards to very precise load monitoring and extremely effective CoolStep for low motor power dissipation.  In case you need more than 4A RMS, this IC of course will not fit.  

Can u share any ref schematics other than evk?

Hi Savy,

I do not have other schematics available which would bring any additional information. Most important is the selection of the MOSFETs. I would also like to point you to some additional circuitry shown in the datasheet:

You may add the gate resistor and diode variant. This can help to optimize EMI later on. Same is for the 1nF capacitors near to the output, plus and LC filter, BW<50MHz. I also recommend adding the RC filter for VS. Use a HF inductivity capable of the motor current, plus a capacitor of 470pF to 1nF.

With these precautions, you have some tuning options later on. 

Hi,

Thanks for suggestions,. i have two queries based on this.

1. As per datasheet diagram, only two gates of MOSFET equipped with diodes. is it correct? What is the basic specification required for diode?

2.  " Use a HF inductivity capable of the motor current, plus a capacitor of 470pF to 1nF. " where this have to add? at H bridge output of mosfet? Do you recommending add ferrite bead in the statement?

1. Either each gate or none - a mix does not make sense. All MOSFET gates should have the same circuitry

2. LC filter at the output, near to connector, to filter out HF coming from switching events of the FETs

1. Any diode specification recommeded for the same?

2. LC filter at the output, near to connector, to filter out HF coming from switching events of the FETs -

Does it mean at the connector where motor connecting ? any ferrite bead specification suggestions?

1. A tiny 30V Schottky diode with 400mA to 1A rating will do, eg. MSS1P3

2. Yes, for each motor line. It can reduce high frequency emission coming from power bridge switching events. Inductivity: Choose a type intended for EMI purpose. Make sure it is rated for full motor current. Lower frequency BW is better / higher dampening at high frequency, but larger and more expensive. This is nothing special to stepper motor operation, it is more a general component you would choose for EMI emission reduction. 

In response 2, what is suggestion, ferrite bead or normal inductor?

I guess this is a cost & size question. Not sure if one or the other is better. Most inductors anyway use a ferrite core, also.

I guess this is a cost & size question. Not sure if one or the other is better. Most inductors anyway use a ferrite core, also.