Dear Design support team.
It is designed as below. VM voltage is 30V. this means DC motor operating voltage is 30V.
Generally condition, I will control the motor using only primary driver IC.
The redundant driver IC is only sleep-mode (VM supplied). the redundant will be operating in primary driver fault.
Is there any problem with this design? In terms of stress or failure due to primary driver operation.
Thank you always.
Hi Daejin,
There no information under what primary driver faults and with what timing the redundant driver would kick-in. Potential failures are always transient in nature and usually not happen in steady state operation. In steady state keeping the redundant driver in sleep-mode to render its output Hi-Z may appear to a plausible approach. Here's the description of the nSLEEP function from the datasheet.
Another gray area for transient play is while parallel connected devices power up. Until internal digital POR and wake up kicks in which could take ~ 1 ms there could be unknown states of the output of the devices. This can lead to asynchronous operation related failures. All these have to be thoroughly studied before going forward with such a design. Power up the devices at the same time will not guarantee the devices come up simultaneously.
My suggestion would be to get two EVMs and evaluate such a design to see if there are any potential failure modes and learn how they could be mitigated. Timing of how the primary is guaranteed to be isolated while the secondary kicks in and kick out is also important. In addition to this load behavior also have to be looked at. Even while the redundant driver is in Hi-Z keep in mind the power FETs body diodes are in the circuit and will be functional.
Regards, Murugavel
