DRV8316 datasheet(84/97 Pages) TI

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11.3 Thermal Considerations

The DRV8316-Q1 has thermal shutdown (TSD) as previously described. A die temperature in excess of 150°C

(minimally) disables the device until the temperature drops to a safe level.

Any tendency of the device to enter thermal shutdown is an indication of excessive power dissipation, insufficient

heatsinking, or too high an ambient temperature.

11.3.1 Power Dissipation

The power dissipated in the output FET resistance, or RDS(on) dominates power dissipation in the DRV8316-Q1.

At start-up and fault conditions, this current is much higher than normal running current; remember to take these

peak currents and their duration into consideration.

The total device dissipation is the power dissipated in each of the three half-H-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 sizing the heatsink.

A summary of equations for calculating each loss is shown below for trapezoidal controland field-oriented

control.

Table 11-1. DRV8316-Q1 Power Losses for Trapezoidal and Field-oriented Control

Loss type

Trapezoidal

Field-oriented control

Standby power

Pstandby = VM x IVM_TA

LDO (from VM)

PLDO = (VM-VAVDD) x IAVDD, if BUCK_PS_DIS = 1b

PLDO = (VBK-VAVDD) x IAVDD, if BUCK_PS_DIS = 0b

FET conduction

PCON = 2 x (IRMS(trap))2 x Rds,on(TA)

PCON = 3 x (IRMS(FOC))2 x Rds,on(TA)

FET switching

PSW = IPK(trap) x VPK(trap) x trise/fall x fPWM

PSW = 3 x IPK(FOC) x VPK(FOC) x trise/fall x fPWM

Diode

Pdiode = IPK(trap) x Vdiode x tdead x fPWM

Pdiode = 3 x IPK(FOC) x Vdiode x tdead x fPWM

Demagnetization

Without Active Demag: 3 x IPK(trap) x Vdiode x

tcommutation x fmotor_elec

With Active Demag: 3 x (IRMS(trap))2 x

Rds,on(TA) x tcommutation x fmotor_elec

Not Applicable

Buck

PBK = 0.11 x VBK x IBK (ηBK = 90%)

DRV8316-Q1

SLVSGK9 – JANUARY 2022

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