DRV8872_15 Datasheet, PDF (12/25 Pages) Texas Instruments – DRV8872 3.6-A Brushed DC Motor Driver With Fault Reporting (PWM Control)

DRV8872
SLVSCZ0A – AUGUST 2015 – REVISED AUGUST 2015
www.ti.com
The DRV8872 has been measured to be capable of 2-A RMS current at 25°C on standard FR-4 PCBs. The max
RMS current will vary based on PCB design and the ambient temperature.
8.2.2.3 Sense Resistor
For optimal performance, it is important for the sense resistor to be:
• Surface-mount
• Low inductance
• Rated for high enough power
• Placed closely to the motor driver
The power dissipated by the sense resistor equals I_RMS ² × R. For example, if peak motor current is 3 A, RMS
motor current is 1.5 A, and a 0.2-Ω sense resistor is used, the resistor will dissipate 1.5 A² × 0.2 Ω = 0.45 W.
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 PCB is shared with other components generating heat, the system
designer should add margin. It is always best to measure the actual sense resistor temperature in a final system.
Because power resistors are larger and more expensive than standard resistors, it is common practice to use
multiple standard resistors in parallel, between the sense node and ground. This distributes the current and heat
dissipation.
8.2.3 Application Curves
Figure 8. Current Ramp With a 2-Ω, 1 mH,
RL Load and VM = 12 V
Figure 9. Current Ramp With a 2-Ω, 1 mH,
RL Load and VM = 24 V
12
Submit Documentation Feedback
Product Folder Links: DRV8872
Copyright © 2015, Texas Instruments Incorporated