Tool/software:
Hello,
I am using this DRV8873H (hardware version) to drive my resistive heat load. This is the input:
Driving configuration:
My questions:
Hi Takuchi-san,
I am using this DRV8873H (hardware version) to drive my resistive heat load. This is the input:
- V supply = 12V
- control PWM = 200Hz
- Rload = 3,3Ohm
Driving configuration:
- MODE = PH/EN
- SR = 13V/us (floating)
My questions:
- The IC gets to about 60degC at 50% duty cycle. Is this normal?
- I am not having Rsense at IPROPI1 and IPROPI2, should this affect performance?
See section 8.2.1.2 Drive Current and Power Dissipation in the datasheet. See below. We can do a rough quick calculation without even including switching losses (you can do this later if you'd like using the formulae under this section). The load current is 12 V / 3.3 Ω = 3.64 A. So the conduction losses in the FET would be (considering 180 mΩ Rdson HS + LS at around 50 °C) 3.64 x 3.64 x 180E-3 = 2.38 W. For 50 % duty cycle consider half the power dissipation 1.99 / 2 = 1.19 W.
TJ = TA + (PD × RθJA) = 25°C + (1.19 W × 27.8°C/W) = 58.15 °C. Switching losses will increase a few °C. So 60 °C is expected operating temperature at TA = 25 °C. Note, this are rough calculations to get die temperature estimates. IC temperature depends on PCB copper, air circulation around the driver and TA temperature.
Not having IPROPI1, 2 should not affect performance.
Regards, Murugavel
