TMCS1108-Q1: output pin filtering

Marvin Gasis Arcangel

Part Number: TMCS1108-Q1

Hi Experts,

Our customer has this question:

"Characteristics warn about capacitance above 1 nanofarad on output (pin 7) for stability. If that is sensitive, what series resistance is enough to place a 0.1 uF after that resistance for filtering?

No discussion of this in the datasheet or evaluation module literature. EVM has 0 ohm and no capacitance on filter on board with no discussion."

I was hoping you could help.

Regards,

Marvin

over 2 years ago

0 Javier Contreras4 over 2 years ago

TI__Mastermind 28250 points

Hello Marvin.

Once you add the resistor the capacitance can increase as it is isolated. The EVM has a 0Ω place holder just so that one has the ability to add/change the resistance value. I would recommend a filter larger than 100Ω due to the output impedance of the device seen on the datasheet. If you would like to understand more about the output impedance you can look at the documents below. Otherwise I would if adding a filter a resistance > 100Ω and then place the capacitor depending on the frequency you would like to filter. I would suggest a frequency below bandwidth of the device of 80kHz.

https://www.ti.com/lit/an/sboa443/sboa443.pdf

https://www.ti.com/lit/an/slya029/slya029.pdf

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TMCS1108-Q1: output pin filtering