• State Resolved
  • Locked Locked
  • Replies 1 reply
  • Subscribers 63 subscribers
  • Views 225 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TPS92692: OPEN CIRCUIT PROTECTION

Abi Varghese
Prodigy 70 points
Part Number: TPS92692

I want to know how open led protection is  implemented in TPS92692. In datasheet Figure 57. LED Open-Circuit Fault, shows current spikes on ILED line (ch 4) at second half of fault  condition. when is it happening?  It is confusing me.

  • 0
    TI__Mastermind 18890 points
    Hi Abi,

    Figure 57 is a scope capture for a Buck Boost configuration when you have an open LED. The way the part works for open LED is it monitors the ouput voltage that is divided down and feedback to the OVP pin. The nominal over votlage for this is 1.228V and when the voltage on this pin is higher than 1.228V we sense an over-voltage fault. With this we will disable the PWM FET Q1 and remove the LED load and pull down SS thus doing a re-soft-start. You can read about this over voltage fault on page 22 of the specification.

    On the scope capture what happens is that we remove the LED load then re-connect it to show the open circuit and recovery process. When LED is first removed, the output voltage will ramp up until it trips the over-voltage condition. When LED is then connected back and because the ouput voltage is high already you will get a fast over-current condition and then it turns the PWM FET off and 36mS then connect the LED load with the PWM FET again but instant current is again over-current condition we will turn it off again. This happens until the ouput voltage is discharge enough to where the over-current does not happens. So the pulsed current is due to this process.

    Thanks Tuan