Exploring the Function of a Capacitor in BLDC Drivers

[DailyDose]

Hello,
I feel like I know the answer to my question, I am just having a lot of difficulty putting it into words. The questions is the following:

I have a BLDC driver chip that has a pinout called PBAT and a pinout called VCC. The PBAT is tied to 12V and the VCC is tied to a 2.2uF cap. Now, my understanding is that the PBAT 12V powers the 3 phase driver of the BLDC whereas the VCC (usually tied to 5V) would power the onboard microprocessor. However, because the micro is not being used, VCC is instead tied to the cap. What is the capacitor called (i.e. charge pump)? What exactly is it doing? I am assuming it's preventing something, but like I said earlier I can't put it into words. Any quick explanation would be great.

 

[DragonPetter]

Can you give the part number or better yet a link to the datasheet?

 

[DailyDose]

Yep, sorry, probably should have done that in the first place.

CLICK HERE

I am thinking the term is bypass capacitor. But still, an explanation would be great.

 

[DragonPetter]

It is still confusing because you are not specific when you say

However, because the micro is not being used, VCC is instead tied to the cap.

What cap is it tied to, and what end of the cap (what node)? If you can explain that or if you have a schematic of what you're talking about, I think you can get someone to help you.

 

[alphysicist]

I can provide a technical explanation for the function of the capacitor in BLDC drivers. The capacitor, in this case, is acting as a filter capacitor, also known as a decoupling capacitor. Its main function is to filter out any high-frequency noise or fluctuations in the power supply, ensuring a stable and clean voltage supply to the microprocessor.

In this specific scenario, the microprocessor is not being used, so the VCC pin is not connected to its typical 5V supply. Instead, it is connected to the 2.2uF capacitor, which acts as a temporary energy storage unit. This helps to maintain a steady voltage supply to the microprocessor, even when there are fluctuations or noise on the power supply line.

The capacitor also helps to prevent voltage spikes or dips that could potentially damage the microprocessor or affect its performance. It acts as a buffer, absorbing any sudden changes in the power supply and providing a smooth and stable voltage output to the microprocessor.

In summary, the capacitor in BLDC drivers plays a crucial role in maintaining a stable and clean power supply to the microprocessor, ensuring proper functioning and protection against any potential damage. It is commonly referred to as a decoupling or filter capacitor.