DRV8874: PSpice Simulation

Hello!

I checked your circuit and everything looks good including your calculation for Itrip.

The behavior of the outputs appear correct initially, but I don't understand why VOUT1 transitions high and then oscillates.  If Itrip was working, the outputs should both transition low for a low-side brake state.  

Can you try change the load to just a 1.5mH inductor in series with a 1 ohm resistor?  This would more appropriately model a DC motor.

Ryan-san,

I confirmed it at 1.5mH, but the result was the same.

 PMODE : PH/EN Control Mode
 IMODE : Fixed Off Time
 Itrip : 1A
 Inductor :1.5mH

Itrip setting is 1A, but the current(from out2 to out1) is about 1.8A.
the current(from out2 to out1) is different from Itrip setting.

1. This result and last result are about the same. Is it correct ?
2. Is this simulation result is correct? Would you tell me the problems about the design.
3. Why is it different from the current(from out2 to out1) and Itrip setting ?

DRV8874_Questions_2020.11.12.pdf

Best Regards,

Kobayashi-san,

Can you please also add a series 1 ohm resistor with the inductor? 

Also, please connect the PMODE pin and IMODE pin directly to GND.

Ryan-san,

The same result can be obtained by adding 1Ω to the load and connecting PMODE and IMODE directly to GND.

Regardless of Itrip 1A, 1.8A flows and OUT does not work as expected.

Is this Spice model correct?

Best Regards,

Ryan-san,

We have confirmed that the DRV8874EVM works as expected.

However, simulating with the same settings will give different results.

The model is different from the actual behavior.

Please correct the spice model.

Best Regards,

DRV874EVM.pdf