UCC256404: Capacitor of BLK_PIN and BW_PIN

Hi Shogo,

Those are the filter capacitors. You can keep both of them to 10pF as shown in the TI EVM.

By the way, the image you have posted is not looks like from the EVM.

UCC25640EVM

Regards,

Yamini.

Thank you for confirmation.

I would like to increase the capacitance of these pins because I am having problems with 10pF.

I would like to increase the capacitance of BLK_PIN to 10uF as a countermeasure for surge testing.

Also, I would like to increase the capacitance of BW_PIN to 100pF as a measure to prevent malfunction due to noise.

Are these okay?

By the way, EVM was referenced here.

https://www.ti.com/jp/lit/pdf/sluuc46

Hi Shogo,

Sorry for the delay.

I will get back to you by the EOD(IST).

Regards,

Yamini.

Hi Shogo,

Thankyou for your patience.

You can use BLK pin capacitor as 10uF, only issue is as BLK pin senses the input voltage, if there is any change in the input , controller senses it with a delay because of high value of the BLK cap. 

You can use BW pin cap as 100pF.

Regards,

Yamini.

Thank you for your reply.

I note that the sence is delayed.

If I want to increase the capacity, is there a limit to the storage capacity?

Hi Shogo,

Please let me know which capacity you are referring to.

Regards,

Yamini.

The capacitance of the BLK_PIN and BW_PIN capacitors.

Hi Shogo,

Thankyou for the clarification.

We do not have a particular maximum capacitor value. It is based on how the delay caused by the capacitor affect your system.

Regards,

Yamini.