LM2901: 3.3V supply low temperature output failed.

user5883945

Part Number: LM2901
Other Parts Discussed in Thread: LM339LV,

Hi,

The customer finds a problem. When LM2901DR is supplied with 3.3V power, the output fails under -10 ° C in a low temperature environment. The waveform is as below, and the output failed, cannot be stabilized. The temperature range indicated in the datasheet is -40~125; In 5V power supply does not have this problem, high temperature test also passed. To do ABA verification, the bad chip was changed to a 5V powered circuit board and the low temperature test was normal.

May I ask what causes this?

-40℃ output

-20℃

-4℃

4 months ago

0 Clemens Ladisch 4 months ago

Guru 244370 points

Please show the schematic.

But this looks as if you are trying to use input voltages above 1.3 V (3.3 V − 2 V), which are outside the valid input voltage range. (The worst case for the input voltage range happens at the lowest temperatures.)

If you cannot change your circuit to use lower input voltages, use a comparator with rail-to-rail inputs like the LM339LV.

0 user5883945 4 months ago in reply to Clemens Ladisch

Expert 1101 points

I see the datasheet supply voltage is 2~30V, 3.3V is between this range, whether there are any errors in the datasheet.

0 user5883945 4 months ago in reply to Clemens Ladisch

Expert 1101 points

0 Chi Nguyen1 4 months ago in reply to user5883945

TI__Genius 11346 points

Hi,

Due to the holidays, our team is out of the office right now. We’ll review your question as soon as we are back.

Thank you for your patience.

0 Clemens Ladisch 4 months ago in reply to user5883945

Guru 244370 points

As shown by the common-mode input voltage range (V_ICR) specification in section 7.13, you must not use input voltages above V_CC − 2 V. Your reference voltage VREF ≈ 2 V is too high.

(The LM2901 actually allows one input to be above the limit, with worse electrical characteristics. But when both inputs are above the limit, it cannot work.)

Change the reference voltage divider (R213/R215) to something like 1 V, and change the input signal divider (R209/R212) to match.

0 Chi Nguyen1 4 months ago in reply to Clemens Ladisch

TI__Genius 11346 points

Thanks Clemens.

For low voltage operation, Id also recommend LM339LV which is p2p and rail to rail input. Otherwise youll need to keep the inputs inside the vcm range as Clemens mentions

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LM2901: 3.3V supply low temperature output failed.