TL331B: Simulation, Comparator not behave as expected

d_zero

Genius 4745 points

Part Number: TL331B
Other Parts Discussed in Thread: TL331, TLV7021, TLV9062

Hi All,

I'm simulating TL331B as inverting comparator with reference 2.5V.

While my input signal on V- is 2.6V then i get the correct output:

TL331_2.5_2.6_OK.TSC

But if i have same reference of 2.5V and change the input voltage to 3.6V then comparator doesn't work as expected:

TL331_2.5_3.6_NOT_OK.TSC

What i'm doing wrong?

Best Regards,

over 2 years ago

+1 kai klaas69 over 2 years ago

Guru 140200 points

Hi,

you violate the input voltage range:

Kai

0 Joe Vanacore over 2 years ago in reply to kai klaas69

TI__Genius 13810 points

Hi Kai,

Thank you for pointing this out for D.

Hello D,

Please try re-simulating after you adjust your input range to meet the input common mode requirements.

Best Regards,

Joe

Applications Engineer

Linear Amplifiers Business Unit | Comparators Product Line (CMPS)

All information in this correspondence and in any related correspondence is provided “as is” and “with all faults”, and is subject to TI’s Important Notice (http://www.ti.com/corp/docs/legal/important-notice.shtml)

0 Paul Grohe over 2 years ago

TI__Guru 54116 points

Hello D,

As Kai and Joe show, you are violating the input voltage range of (V+) - 2V. Your supply voltage is +5V, so the input limit is +3V max per input.

These newer models show violations (input or supply) by forcing their output to half the V+ supply voltage, regardless of the pull-up voltage.

So keep your input voltage below 3V, and the output will be correct.

0 d_zero over 2 years ago in reply to Paul Grohe

Genius 4745 points

Hi All,

i changed to TLV7021 comparator.

Please see my simulation. Would you add some additional footprint placeholder to demo PCB?

DAC_PWM_ACTIVE_COMPARATOR_TLV7021.TSC

Best Regards,

David.

0 kai klaas69 over 2 years ago in reply to d_zero

Guru 140200 points

Hi,

looks good in my sight. The TLV9062 looks fast enough to drive the rapidly changing current demands when the TLV7021 toggles.

A place holder for what?

Kai

0 Paul Grohe over 2 years ago in reply to d_zero

TI__Guru 54116 points

Hello D,

If this is for a PCB layout, beware that there are at least 3 different different pinouts for the SOT/SC-70 packages.

The TL331 has a different pinout than the TLV7021. So you really need to pick which device you are using BEFORE layout. You may not be able to substitute with an alternate device later due to the pinout.

0 Joe Vanacore over 2 years ago in reply to Paul Grohe

TI__Genius 13810 points

Hello D,

There have not been any posts to this thread for quite some time. I will now close this post. If you have further questions, please respond to this thread or create a new one.

Best Regards,

Joe

Applications Engineer

Linear Amplifiers Business Unit | Comparators Product Line (CMPS)

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TL331B: Simulation, Comparator not behave as expected