TL331: Old and new versions of TL331 comparators.

Andrii Novatskyi

Part Number: TL331
Other Parts Discussed in Thread: LM339, LM393, LM2901, TLV1805, TLV1701, TLV1861

Dear Sirs

According to "Application Design Guidelines for LM339, LM393, TL331 Family Comparators Including the New B-versions" there are versions of LM339 and LM2901 with old behavior(non-inverting). Could you please suggest any version of TL331 or any other comparators(single or dual packages) with old behavior?

Thank you in advance.

over 1 year ago

0 Clemens Ladisch over 1 year ago

Guru 281510 points

The old devices are being phased out. This is why the documentation tells you not to rely on this behaviour.

If you want to have consistent behaviour over the entire voltage range, use comparators with rail-to-rail inputs, e.g., TLV1701/TLV1805.

0 Andrii Novatskyi over 1 year ago in reply to Clemens Ladisch

Prodigy 40 points

Thank you for early reply. But I am interested in the old behavior of the comparator to set low state when both inputs are higher than common-mode voltage. Rail-to-rail comparator can not provide such behavior.

0 Clemens Ladisch over 1 year ago in reply to Andrii Novatskyi

Guru 281510 points

You should never go beyond the valid common-mode range.

What is the actual problem you're trying to solve? If you want to use voltages above V_CC, see the TLV1861.

0 Andrii Novatskyi over 1 year ago in reply to Clemens Ladisch

Prodigy 40 points

It is a legacy product. The input voltage can be above common-mode range but always lower than Vcc. According to the datasheet for TL331 there is no problem to work beyond common-mode range until input voltage are lower than Vcc.

+1 Clemens Ladisch over 1 year ago in reply to Andrii Novatskyi

Guru 281510 points

That is not what the documentation says.

The absolute maximum ratings allow higher voltages, but they guarantee only that the device does not get damaged; they do not guarantee correct operation.

The TL331 will work correctly if one input is above the limit, but will violate other electrical characteristics such as the propagation delay. When both inputs are above the limit, the output depends on implementation details. This was never guaranteed.

If your circuit depends on the old behaviour, then your only choice is to buy enough of the old chips.

+1 Andrii Novatskyi over 1 year ago in reply to Clemens Ladisch

Prodigy 40 points

Thank you for your time and detailed reply. Have a nice day.

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TL331: Old and new versions of TL331 comparators.