SLVSEC9C September 2019 – February 2020 DRV8904-Q1 , DRV8906-Q1 , DRV8908-Q1 , DRV8910-Q1 , DRV8912-Q1
PRODUCTION DATA.
The current path for a motor connected in full-bridge is through the high-side FET of one half-bridge and low-side FET of other half-bridge. The power dissipation of DRV89XX-Q1 depends on the amount of current flowing through the full-bridge and the number of such full-bridges which are operating together. The power dissipation (PFB_CONT) in a single full-bridge configuration for continuous mode depends on the motor rms current (IRMS) and high-side (RDS(ON)_HS) and low-side (RDS(ON)_LS) on-state resistance as shown in Equation 1.
The power dissipation (PFB_STALL) in a single full-bridge configuration for motor is a stall condition depends on the motor peak current (IPEAK) and high-side (RDS(ON)_HS) and low-side (RDS(ON)_LS) on-state resistance as shown in Equation 2.
Now, the power dissipation for operating mode and stall mode in single full-bridge for the typical application as shown in Table 92 is calculated in Equation 3 and Equation 4 respectively.
For NF-full bridges in operating condition and NS-full bridges in stall condition, the total driver power (PDRV) is expressed and calculated as shown in Equation 5.
NOTE
This power calculation is highly dependent on the device temperature which significantly effects the high-side and low-side RDS(ON) of the FETs. For more accurate calculation, consider the dependency of RDS(ON) of FETs with device temperature.