DRV8889-Q1: Capacitor on VCP pin

Masaru Oinaga

Part Number: DRV8889-Q1

Hello, Team,

Customer is considering DRV8889-Q1 for their new project and has question about capacitor connected to VCP pin.

Its capacitance is 0.22uF in the datasheet, but because of limitation in their device selection, they might need to adopt 0.47uF instead.

a. Can we use 0.47uF instead of 0.22uF?

b. If yes, what would be the side effect of using 0.47uF instead of 0.22uF? What do we need to take care?

Best,
Masaru

over 3 years ago

0 Ryan Kehr over 3 years ago

TI__Guru 55605 points

Hello,

Thank you for your post. I will need to check with design team. Might have to also increase CPH-CPL cap to keep same ratio. Would that be possible?

Regards,

Ryan

0 Masaru Oinaga over 3 years ago in reply to Ryan Kehr

TI__Expert 4365 points

Hello, Ryan,

Thank you for the reply. We are aware that CPH-CPL cap is related to VCP cap. They could increase the CPH-CPL cap as well.
Please guide us how to calculate the appropriate capacitances for VCP and CPH-CPL caps.

Best,
Masaru

0 Ryan Kehr over 3 years ago in reply to Masaru Oinaga

TI__Guru 55605 points

Ok, I am checking with design. Thank you!

+1 Ryan Kehr over 3 years ago in reply to Ryan Kehr

TI__Guru 55605 points

Hello, sorry for late reply:

a. Yes. 0.47uF can be used. The transient performance will be better during OUT node switching for higher capacitance.

b. The initial ramp up of VCP-VM to reach the regulation voltage takes longer time, but will be within the the tWAKE, tON specs given in the EC-table for 0.47uF including the tolerance. No specific action from customer.

This is all assuming the flying cap (CPH-CPL) remains at 22nF.

Regards,

Ryan

0 Masaru Oinaga over 3 years ago in reply to Ryan Kehr

TI__Expert 4365 points

Hello, Ryan,

Thank you very much for your support!

Best,
Masaru

Motor drivers

Motor drivers forum

DRV8889-Q1: Capacitor on VCP pin