DRV2667 how to consider power consumption

Hi Machida,

The power consumption is very dependent on the piezo (est. capacitance), the output voltage, and the frequency. This design guide can help calculate the power consumption.

Hi Griffin-san,

Thank you for your reply.
But I could not access following URL which you suggseted for design guide.

www.ti.com/.../drv8662-2665-2667_design_tool

Could you attach this tool ?

Best Regards,
Machida

Griffin-san,

Sorry, I could access above site when I tried to access after few minutes later.
So you do not need to send tool for me.
(Maybe, the problem causes due to web browser....)

Best Regards,
Machida

Hi Griffin-san,

I checked attached xls file(DRV8662, DRV2665, and DRV2667 Design Equations.xlsx) to calculate power consumption.
However, I could not understand which current should be used to estimate supply current.
There are three types of current in this xls sheet.
* Iout_max
* Ibat_max
* Ilimit_actual

I understood that Ilimit_actual means spec for allowable current of inductor. So this is not actual current for use case.
In my understanding, sum of Iout_max and Ibat_max is required supply current for source.

Is my understanding correct ?

Best Regards,
Machida

Hi Machida,

I_outmax will get you the peak current through the piezo load.
I_batmax is the typical peak current seen by the battery.
So the best way to calculate the power consumtion is to find the power needed for the load (piezo). Then use efficiency to calculate the input power. This is what the equation for I_batmax does; you just need to multiply by the votlage supply rail.

Hi Griffin-san,

Thank you for your reply.
I understood meaning of both I_batmax and I_outmax.
However, i would like you to confirm how user find efficiency of this device.

>This is what the equation for I_batmax does; you just need to multiply by the votlage supply rail.
I understood meaning of above is below.

* Power consumption = VDD * I_batmax
(I_batmax = 2*PI()*fin_max*Cactuator*Vboost*(Vboost/(VDD*uboost)))

I understand that some parameters such as "fin_max" and "Cactuator" depend on usecase.
But, only parameter of "uboost"(Efficiency) depends on device.

So, could you please tell me how user find efficiency for each usecase ?

Best Regards,
Machida

Hi Griffin-san,

Could you please give me your comment ?

Best Regards,
Machida

Machida,

You can refer to the efficiency graphs for the DRV2700 to find the uboost number for the different boost voltages.