DRV8434S: Driver IC not gives gives Output.

Hi Dinesh, 

Can you please elaborate a bit further on what you mean by 'IC generates 5V' and 'output is not getting ON'?

Also, please share:

1. your input voltage
2. itrip current setting (or VREF value)
3. Decay mode
4. Step input waveform
5. Output current waveform
6. Microstepping setting

For reference, this is the data sheet section describing Open Load Detection. I would also urge you to verify that the device is not in SLEEP mode. 

Regards, 

Karan

Hi Karan Doshi,

Thank you for your reply.

1. your input voltage - 36V
2. itrip current setting (or VREF value) - VREF - 3.3V
3. Decay mode - Smart tune dynamic decay
4. Step input waveform - We have 4 motors 30rpm - 2 nos, 80rpm - 1 nos, 250rpm - 1 nos. 30rpm - 3200steps/sec, 80rpm - 8533steps/sec, 250rpm - 26666steps/sec
5. Output current waveform - No output is generated in output side.
6. Microstepping setting - 1/32

Device is not in sleep mode we have verified it.

we already used same IC in VQFN package so software is same. just changed the package to HTSSOP.

Herewith I have attached both the schematic for your reference.

Thanks. Please give me a day to respond to this.

Sure.

Hi Dinesh, I'm trying to debug and will keep you updated of the progress. Meanwhile, can you please do the following:

1. Disable the OL detection (EN_OL=0b) and check the outputs again. Please send me a scopeshot if outputs appear. I'm assuming you have the stepper connected at the output but the fault is still being detected. 
2. Can you send a scopeshot of the STEP input at the STEP pin of the device?

Thanks, 

Karan 

Hi Karan.

I will disable the OL detection and send you the scope shot for output and also STEP.

TRQ_DAC is 56%.

Thanks, the waveform should help. The itrip value is 1.4A so I can eliminate that as a cause. I'm curious about the OL detection. What were the values in OL_A and OL_B register bits when open load fault was detected? 

Additionally, you mentioned that the IC generates 5V. Can you tell me which pin you observed this 5V output at?

Hi Karan,

OL_A and OL_B we haven't read that bit. we will check that and get back to you. DVDD pin generates 5V.

Hi David, 

I can verify that the schematics are not different other than the LED circuit at the nfault pin which should not affect OL detection. The values for itrip look fine for now, but I would need to see the following to progress:

1. OL_A and OL_B bit values. 
2. Output waveform with OL detection enabled (with STEP and DIR signals)
3. Output waveform with OL detection disabled (with STEP and DIR signals

Awaiting your response. 

Regards, 

Karan