Hi,
I am considering the allowable temperature of the device in TPS54302.
TPS54302 is supplying power to the motor.
1.5A is the maximum current value flowing when the motor is running.
The waveform of the output voltage of TPS54302 at that time is attached.
The time during which the motor is operating is 857ms(max).
Since the resistance of the cable connecting the output of TPS54302 and the motor is 1.93Ω, a voltage drop occurs as shown in the attached figure.
1.4A flows at the point where the voltage drop is the highest.
I calculated the loss of the device when flowing 1.4A using WEBENCH.
The result was about 0.65W. Because θJA = 87.1°C / W, ΔTj = 57°C.
From this result I think that there is no problem even at 60℃ environmental temperature.
However, there is a possibility that a maximum of 2.5A flows due to variations in the drive current of the motor.
The calculation result of loss by WEBENCH at 2.5A is 1.41W.
The temperature rise due to this loss exceeds TJ.
I want to ask a question.
2.5A does not flow steadily, but can it be said that it is not appropriate to use this device if there is a possibility of exceeding TJ still?
(specification)
VIN:28V
VOUT:7.2V
IOUT:1.4A
Environmental temperature:-20°C to 60°C
Best Regards,
