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I am using DRV8801EVM and sense resister changed from 0.2ohm(default) to 2.2ohm. I meet issue when VBB voltage is supplied to EVM. Issue is nFault is every time Low out put when VBB voltage is supplied to EVM. But DC motor can operate. Why does this issue occur? Could you solve this issue?
[Starting procedure] 1.EVM connects to PC and GUI starting up. -> nFault is High
2.Voltage is supplied at 18V by Stabilized power supplies. -> nFault is Low
3."Enable motor" bottum is ON. -> nFault is Low, but Motor can operate. Best regards,Shimizu
nFAULT is a status signal only and H-bridge can operate even with nFAULT low till VBB down to 8V. But definitely, we need to find the reason why nFault is asserted low. Can you provide little more inputs?
Milan-Motor Application Team
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In reply to Milan Rajne:
Thank you for your support. I chacked your question. Please see the attached file. But I am going to trying tommorow in case of Rsence=0.2ohm.
In reply to masahiko shimizu:
Thank you for your support.
I checked the case of Rsense = 0.2ohm.
But the results is same as the case of Rsense=2.2ohm.
Please see the attached file. ->"Rsense=02.ohm" tab in xlsx file.
I think that VOUT+pin in waving when 18V is supplied.
Is internal FET motion normal?
Thanks for conducting the experiment and providing experimental waveforms. So now it’s clear that nFault is not triggered by Rsesne value. As you pointed out that Vout+ output goes in to ripple condition and its effect is more predominant figure 4.
Refer to attached pircture, with Rsense=2.2, there is huge ripple on Vout+ during high/on conditions. It looks like that due to ripple, minimum voltage level is ~12V which is close to VBBNFR level and may be causing nFault trigger. In order to confirm, can you please simultaneously capture the VBB, Vout+ and Vout- (keeping all channels at 10V/Div) at motor running condition?
Unfortunately, I do not have EVM with me at present, I have ordered couple of them but it’s going to take 4-5 days to get EVM. Meanwhile, if you have another EVM, you can repeat the same experiment, to remove any possibility of device or any component damage on present EVM.
Milan-Motor Applicaiton Team
Thank you for your support.
I confirmed VBB, VOUT+ and VOUT- at motor running condition. Please see the attached file.
I will get a new EVM tomorrow. I will try it tomorrow. Best regardsShimizu
Thanks for capturing the waveforms. It's clear that Vout+ output is not correct, it has ripple even though VBB is clean.
Looks like H-bridge for Vout+ is not functioning properly. Test with new EVM, and I hope you will not see the issue,
Meanwhile here, I tested new EVM and it is working absolutely fine.
Thank you for your support. I confermed nFault signal with new EVM. This board operated normally. Thanks a lot. Best regardsShimizu
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