Part Number: DRV8308
Hi, I have an issue with the DRV8308's FAULT register.
I am using an MCU of microchip dsPIC33 to control the DRV8308. The Problem is, I have configured the registers correctly and the read value of the registers is the same as I expected. But after I complete the configuration and give the DRV8308 a PWM signal, the value of register 0x2A becomes 0x0059, which is CPFAIL, UVLO, and OCP bits are 1 and even the reserved bit 6, and the FAULTn pin turns active. This happens not only when the PWM signal is given, but when a signal from MCU is sent. This recovers when I disconnect the MCU and the DRV8308, then the FAULTn pin becomes normal, obviously I can't control the motor in this situation.
Here are the value of the registers:
The value of 0x2A before configuration is 0x0018 ( default value ).
This confuses me, so hope that there is anyone who can help me.
The schematic is inserted and let me know if there is any other information is required.DRV8308_2.pdf
By the way, I have changed both the DRV8308 and the isolation chip, but the problem still the same.
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A modification not shown in the schematic is that I have added pull up resistors for the spi output of DRV8308, so the problem is not caused by this.
In reply to user6100253:
Thanks for posting on the MD forum!
Once the system is powered and enabled, if you clear the faults, do they come back?
In reply to Adam Sidelsky:
I try to clear the faults after the system is enabled, but the faults still come back.
What I can't understand is that it seems the faults only come back when connecting the system to an MCU.
If the MCU is connected and the faults are cleared after device power up and initialization, which faults occur again?
The CPFAIL, UVLO, and OCP faults occur again, and the value of register 0x2A is 0x0059.
Please provide a scope image of the VM pin and VCP pin while the device is operating. We need to check if the power supply or charge pump voltages are dipping.
Here is the scope image of the 2 pins, the charge pump voltage seems not dipping but rising when enabled, is this normal?
The VM and VCP are not dipping so I don't think these are real faults. Likely removing the MCU or similar is causing the issue.
Thank you for your answering to this question, I have found that I connect the U, V, W pins and the HSG pins wrongly, maybe this causing the problem.
I'll make another circuit board and see whether it works.
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