SLVSE65C July 2018 – December 2023 DRV8847
PRODUCTION DATA
Refer to the PDF data sheet for device specific package drawings
For optimal performance, the sense resistor must:
The power dissipated by the sense resistor equals IRMS2 × R. In this example, the peak current is 900 mA, the RMS motor current is 490 mA, and the sense resistor value is 125 mΩ. Therefore, the sense resistors (RSENSE12 and RSENSE34) dissipate 30 mW (490 mA2 × 125 mΩ = 30 mW). The power quickly increases with higher current levels.
Resistors typically have a rated power within some ambient temperature range, along with a derated power curve for high ambient temperatures. When a printed circuit board (PCB) is shared with other components generating heat, margin should be added. For best practice, measure the actual sense resistor temperature in a final system, along with the power MOSFETs, because those components are often the hottest.
Because power resistors are larger and more expensive than standard resistors, the common practice is to use multiple standard resistors in parallel, between the sense node and ground. This practice distributes the current and heat dissipation.