TL331 in deadlock application

Helen chen

Other Parts Discussed in Thread: TL331

Hi,

Here I want to ask a question about the comparator TL331 in deadlock application. Could this comparator still realize the dead-lock function with the following weak pull-up? Please help to check the following schematic. This schematic is for powerbank and bluetooth speaker application.

over 9 years ago

0 Helen chen over 9 years ago

TI__Mastermind 40080 points

Could somebody reply this question by today? because we want to release the pcb by this week.

Thanks,

Helen

0 Ron Michallick over 9 years ago

TI__Guru**** 169136 points

Helen,

Maximum leakage at output is 1uA. That is just 0.1V on R16. R16 is fine (for TL331).
As drawn the TL311 will be a latch that is always high or low depending on power up order and a bit of luck.
What is the TL331 supposed to do?

0 Helen chen over 9 years ago in reply to Ron Michallick

TI__Mastermind 40080 points

Ronald,

Thanks for the answer.
In this ciruit, The TL331's Vcc and Vref connected to its pin(-) will on firstly. Then we apply the EN signal to make sure during the start-up or normal working condition TL331 can output low≈0V. But when the Vsense is high, TL331 will output high and always high if EN signal is always =5V.
Is this logic OK?

BR,
Helen

0 Ron Michallick over 9 years ago in reply to Helen chen

TI__Guru**** 169136 points

Helen,

That will work but I have one question. Why would Vsense ever go high, >0.5V?

0 Helen chen over 9 years ago in reply to Ron Michallick

TI__Mastermind 40080 points

Thanks!

During short circuit, the current through R10 will be very high, thus will make the Vsense higher than 0.5V.
But in the further design, I will change the Vref to 0.3V.

What is your concern?

0 Ron Michallick over 9 years ago in reply to Helen chen

TI__Guru**** 169136 points

Helen,

I did not notice that Vsense was also connected to R11.

Now the circuit makes sense to me.

0 Helen chen over 9 years ago in reply to Ron Michallick

TI__Mastermind 40080 points

Thanks :)

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TL331 in deadlock application