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• TI Thinks Resolved

# DRV8870: Largest RMS output current

Part Number: DRV8870

Hi team,

Customer wants to use DRV8870 as a resistive load driver. The largest RMS current would be about 2A(VM is about 18V@2A.) Do you think DRV8870 is a good device for this application.

Thanks.

Robin

• Hello Robin,

Yes, you can use the DRV8870 as a resistive load driver. However, make sure that the peak output current is below 3.6A or it could potentially overheat the part.

Regards,
Pablo Armet
Motor Applications Team

• In reply to Pablo Armet:

Hi Pablo,

Do we have tested our EVM for 2A RMS loading? What is the temperature rising?

The board may work at 60C ambient temperature, the temperature rising is required to below 40C?

Could DRV8870 meet this requirement? If not, any other device suggested?

Thanks.

Robin

• In reply to Robin Yu:

Hello Robin,

We have not tested the EVM for temperature rise using a 2A RMS loading. However, a quick calculation using the equation on section 10.4 of the datasheet can be used to estimate the temperature rise for a 2A rms loading.

Power = (I_RMS)^2*(high side R_DS(on) + Low side R_DS(on))

Power=(2)^2*(0.307+0.258)=2.26W

Temp_rise=Power*R_JA=2.26*41.1=92.9C rise.

With 2Arms, the estimated temperature rise will be 92.9C. In order to obtain a temperature rise below 40C, the current needs to be below 1.4 RMS.

The DRV8874 is a good alternative part that can achieve a temperature rise below 40C with 2Arms. the DRV8874 has combined high side and low side R_DS(on) of 200mohms and junction-to-ambient resistance of 36C/W. The estimated temperature rise will be around 30C with 2A_rms. However, this is just a rough estimation and will depend on how the device is soldered onto the board as well as the PCB design. To learn more, read the Semiconductor and IC Package Thermal Metrics app note.

Regards,
Pablo Armet
Motor Applications Team

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