DRV8307 LOCKn active

Vladan Jevremovic

Prodigy 20 points

Other Parts Discussed in Thread: DRV8307, DRV8308

At what speed is DRV8307 declaring LOCKn signal?

Additionally, how long should the speed be constant before the LOCKn signal goes active?

There is no mention of these two facts in the DRV8307 datasheet (unlike DRV8308 that has a very detailed description).

over 7 years ago

0 Rick Duncan over 7 years ago

TI__Guru** 114905 points

Hi DDC2015,

We will investigate and reply soon.

0 RE over 7 years ago

TI__Mastermind 20985 points

DDC, good observation that the DRV8308 has more detailed info. The DRV8307 effectively has a 12.5% speed threshold (SPEEDTH) and requires 4 Hall_U periods to lock. The HALL_U frequency must be faster than 2Hz for lock to occur.

Best regards,
RE

0 Vladan Jevremovic over 7 years ago in reply to RE

Prodigy 20 points

Many thanks for your prompt reply. I have two more questions:

- When does the DRV8307 come out of a LOCK state? Is it when the frequency drops below 2Hz - 12.5% or is it something else (additional criteria)?
- What is the preset value of MOD120 register in DRV8307 - 2048 or 4096?

0 RE over 7 years ago in reply to Vladan Jevremovic

TI__Mastermind 20985 points

2048 (the input duty cycle matches output).

I'm honestly not sure on the exact criteria to lose lock. We can look into that. Staying within 12.5% speed should definitely maintain lock.

Best regards,
RE

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DRV8307 LOCKn active