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Original question:

ONET1151L: The laser can not emit light when the fault enable bit FLTEN is set to 1

ONET1151L: Fault thresholds

Rohan Patel
Prodigy 50 points
Part Number: ONET1151L

Tool/software:

Hi,

If we enable FLTEN, we are always faulted. We are using digital monitor for bias and photodiode and so register 10 is 0x3. I do not know what scale the fault thresholds registers are, these are 8-bit registers whereas registers 4-5 for bias are 10 bit and the monitor for photodiode is also 10-bit. 

How do you use the fault monitor as intended.

Thanks,

Rohan

  • 0
    TI__Mastermind 30180 points

    Hi Rohan,

    We are looking into this question and will follow up today.

    Best,

    Shane

  • +1 in reply to Shane Hauser
    TI__Mastermind 30180 points

    Hi Rohan,

    I'm not able to find a formula for relating the fault threshold values to the set bias current values. It may be best to set the bias current as needed, then tune the threshold registers to be above this set bias current through test/check.

    Rohan Patel said:
    How do you use the fault monitor as intended.

    The fault monitor will set the FLT flag when a fault condition presents itself (Exceeded voltage/current threshold). If you're always getting a fault, its possible the fault thresholds for DMONB(reg 11)/DMONP(reg 12) are set too low. Can you try using a larger value in these threshold registers to see whether this causes the fault to go away?

    Best,

    Shane