LM2901AV-Q1: Vcc=0 conditions

Daria Kiseleva

Intellectual 2375 points

Part Number: LM2901AV-Q1
Other Parts Discussed in Thread: LM339LV-Q1, LM2901AV

Tool/software:

Hello colleagues,

The question is related to LM2901A-Q1,
when it is not powered (Vcc=0)

What happens in these conditions:

If one output port is pulled up to Vx (e.g. to Vx= 5V).
I assume it is not conducting, and nothing goes wrong, since it is an Open Collector up to (at least ) 36V.

Is this assumption correct?

2. If one input port is pulled up to Vx with a Rx resistor (e.g. Vx= 5V, Rx= 10 KOhm)
Taking into consideration the simplified schematic of the datasheet (depicted above), nothing should happen,

but it depends on the breakdown voltage levels of the diodes and of the EB junctions of the pnp BJTs.
Is this assumption correct?
Will the input port leak any current into GND or Vcc?

Thank you,

Daria

2 months ago

0 Clemens Ladisch 2 months ago

Guru 303950 points

1. The absolute maximum ratings allow this. The leakage current is specified as I_OH.

2. The absolute maximum ratings allow this.

See sections 7.4, 6.7, and 6.8 of the Application Design Guidelines for LM339 Family Comparators.

0 Alex L 2 months ago in reply to Clemens Ladisch

Prodigy 150 points

Dear Clemens

Thank you very much.
The app.note was very complete and interesting.

Another point:
so, you don't recommend working with LM2901AV-Q1 and either Vcc-2V < VIN+ < Vcc-1.5V or Vcc-2V < VIN- < Vcc-1.5V,
do you?
However, is performance @ +25°C < Tj < 125°C guaranteed in the above conditions?

Best regards

0 Clemens Ladisch 2 months ago in reply to Alex L

Guru 303950 points

See the V_CM/V_ICR specification in the datasheet for what is guaranteed.

Do you really have signals between V_CC − 2 V and V_CC − 1.5 V? For 5 V systems, a low-voltage, rail-to-rail comparator like the LM339LV-Q1 would be a better idea.

0 Alex L 2 months ago in reply to Clemens Ladisch

Prodigy 150 points

Dear Clemens

thank you very much for the valuable info.

Regards

Alex

0 Alex L 2 months ago in reply to Alex L

Prodigy 150 points

Dear Clemens

Just one more question:
how would you bias non-used LM2901AV comparators?
Is VINx- = Vcc safe, since it violates VINx- < Vcc-2V rule? (OUTx is obviously not working)
If i.e. VINx+=GND, it doesn't violate the common mode range rule either.

Thank you in advance. Best regards

0 Clemens Ladisch 2 months ago in reply to Alex L

Guru 303950 points

When you do not care about the output, the common-mode range does not matter. Anyway, see section 9.1 of the appnote.

Amplifiers

Amplifiers forum

LM2901AV-Q1: Vcc=0 conditions