LM741: Voltage comparator

Jonathan Navor

Part Number: LM741
Other Parts Discussed in Thread: LMV331, LM35

Hi Team,

Greetings. I would like ask for your assistance. I am posting this inquiry in behalf of our customer.

Customer's Inquiry:

I designed a voltage comparator. See attached schematic. In simulator that design works exactly as it should. The output is low until the voltage on pin 3 rises above the voltage on pin 2. However what I am seeing when the device is actually built is that the out put is high all the time. I cannot find any reason for this.

HV Switch.pdf

We are looking forward for your response. Thank you in advance for the support.

Best regards,

Jonathan

over 3 years ago

0 kai klaas69 over 3 years ago

Guru 140200 points

Hi Jonathan,

the LM741 is unsuited here because it cannot work with a 5V supply voltage. Also, you violate the common mode input voltage range of LM741.

Why not taking a comparator like the LMV331, e.g.?

As the output signal of LM35 is changing rather slowly, you should add some hysteresis to the comparator :-)

Kai

0 Former Member over 3 years ago

Hello Jonathan,

In addition to Kai's comments, I would like to point out that a very similar question is answered here. I believe the customer may be the one asking the question.

Regards,
Daniel

0 Jonathan Navor over 3 years ago in reply to Former Member

TI__Expert 7815 points

Hi Daniel,

Thank you so much for the response. For us to have proper alignment and tracking you may close this thread and reply to customer's post directly.

Best regards,

Jonathan

0 Former Member over 3 years ago in reply to Jonathan Navor

Hi Jonathan,

Will do.

Regards,
Daniel

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LM741: Voltage comparator