DRV8839 Datasheet, PDF (10/17 Pages) Texas Instruments – LOW VOLTAGE DUAL 1/2-H-BRIDGE DRIVER IC

DRV8839
SLVSBN4 – JANUARY 2013
THERMAL INFORMATION
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Thermal Protection
The DRV8839 has thermal shutdown (TSD) as described above. If the die temperature exceeds approximately
150°C, the device will be disabled until the temperature drops to a safe level.
Any tendency of the device to enter thermal shutdown is an indication of either excessive power dissipation,
insufficient heatsinking, or too high an ambient temperature.
Power Dissipation
Power dissipation in the DRV8839 is dominated by the power dissipated in the output FET resistance, or R_DS(ON).
Average power dissipation when running a stepper motor can be roughly estimated by:
P_TOT = R_DS(ON) x (I_OUT(RMS))²
(1)
Where P_TOT is the total power dissipation, R_DS(ON) is the resistance of the HS plus LS FETs, and I_OUT(RMS) is the
RMS output current being applied to each winding. I_OUT(RMS) is equal to the approximately 0.7x the full-scale
output current setting.
The maximum amount of power that can be dissipated in the device is dependent on ambient temperature and
heatsinking.
Note that R_DS(ON) increases with temperature, so as the device heats, the power dissipation increases.
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