TLC272: Used as comparator with positive feedback

Zhou Fang67

Expert 4250 points

Part Number: TLC272

Hi Expert,

TLC272 is used as comparator with positive feedback. There is no specified delay requirement.

Is there specified risk to implement commparator circuit like below?

Thanks.

Zhou

over 6 years ago

0 kai klaas69 over 6 years ago

Guru 140200 points

Hi Zhou,

the comparator should work. But I would worry about the left TLC272. What is the input signal "N"?

Kai

0 Bala Ravi over 6 years ago

TI__Expert 6625 points

Hi Zhou,
The comparator setup in the middle will work fine. For a 5V supply, your input common-mode range is GND to 4V (this information can be found in the datasheet). As long as you stay within this range your circuit should work fine. I see that you're using Vref = 2.5V as your non-inverting input which is well with the range of 0 to 4V.

For any op-amp the common-mode voltage is set by the non-inverting input of the op-amp. So the best practice is to use an inverting configuration, which is what you're using here.

I hope this helps!

Best Regards,
Bala Ravi

0 Zhou Fang67 over 6 years ago in reply to kai klaas69

TI__Expert 4250 points

Hi Kai,

TLC272IDR I version.

Thanks..

0 kai klaas69 over 6 years ago in reply to Zhou Fang67

Guru 140200 points

Hi Zhou,

may I again ask about U13A? U13A will only work as amplifier, if the input voltage "N" is negative. Is this the case?

Kai

0 Zhou Fang67 over 6 years ago in reply to kai klaas69

TI__Expert 4250 points

It doesn't matter. It is used to for OC protection. N is a node connected to sensing resistor.

0 kai klaas69 over 6 years ago in reply to Zhou Fang67

Guru 140200 points

And is the potential at "N" negative referred to the potential of "N1"?

Kai

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TLC272: Used as comparator with positive feedback