SLVSNG2 August 2026 DRV8378-Q1
ADVANCE INFORMATION
The power loss in DRV8378-Q1 include standby power losses, LDO power losses, FET conduction and switching losses, and diode losses. The FET conduction loss dominates the total power dissipation in DRV8378-Q1. At start-up and fault conditions, the output current is much higher than normal current; remember to take these peak currents and the duration into consideration. The total device dissipation is the power dissipated in each of the three half bridges added together. The maximum amount of power that the device can dissipate depends on ambient temperature and heatsinking. Note that RDS,ON increases with temperature, so as the device heats, the power dissipation increases. Take this into consideration when designing the PCB and heatsinking.
A summary of equations for calculating each loss is shown below for trapezoidal control.
|
Loss type |
Trapezoidal |
Field-oriented control |
|---|---|---|
|
Power loss due to Quiescent current |
Pstandby = VM x IVM_TA | |
|
LDO |
PLDO = (VM-VGVDD) x
IGVDD PLDO = (VM-VAVDD) x IAVDD |
|
|
FET conduction |
PCON = 2x (IPK(trap))2 x Rds,on(TA) | PCON = 3x ( IRMS(FOC))2 x Rds,on(TA) |
|
FET switching |
PSW = IPK(trap) x VPK(trap) x trise/fall x fPWM | PSW = 3x IRMS(FOC) x VPK(FOC) x trise/fall x fPWM |
|
Diode |
Pdiode = 2x IPK(trap) x VF(diode)x tDEADTIME x fPWM | Pdiode = 6x IRMS(FOC) x VF(diode) x tDEADTIME x fPWM |