DRV8876-Q1: CBulk recommended value?

Yoshiki Ochi

Expert 7545 points

Part Number: DRV8876-Q1

Hi team,

Do you have recommended capacitance about "CBulk" in "Figure 19. Typical Application Schematic"?

Or could you tell me how to calculate "CBulk" value?

Regards,
Ochi

over 3 years ago

0 Ryan Kehr over 3 years ago

TI__Guru 54645 points

Ochi-san,

There is an application note that can be referred to.

Please find SLTA055 on the TI website.

0 Yoshiki Ochi over 3 years ago in reply to Ryan Kehr

TI__Expert 7545 points

Hi Ryan,

I guess equation (9) is bulk capacitor calculation, is it correct?

Then, what does transient current "ITR" mean? In the case the motor steady state current is 1A, is ITR 1A?
If no, could you tell me an example picture for "transient current" and which value is "transient current"?

In addition, does "L" mean motor inductor and ΔVn mean allowable input voltage peak to peak ripple voltage?

Regards,

Ochi

0 Yoshiki Ochi over 3 years ago in reply to Yoshiki Ochi

TI__Expert 7545 points

Or in the case D=0.8 and Iout=1A, then transient current is 1A/0.8=1.25A, is my understanding correct?

Regards,
Ochi

0 Ryan Kehr over 3 years ago in reply to Yoshiki Ochi

TI__Guru 54645 points

Ochi-san,

Itr is the input current to the motor driver. It will be higher than output current because of efficiency loss. It can either be calculated or measured.

L is the motor inductance, yes.

Delta Vn is the allowable ripple voltage, yes.

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DRV8876-Q1: CBulk recommended value?