LM2903B: Query regarding performance limitation observed in this OP-amp device

Sagar Nikam

Prodigy 30 points

Part Number: LM2903B
Other Parts Discussed in Thread: LM393LV, TLV1702, TLV1822, LM2903

Tool/software:

Dear Team,

I am using LM2903BIPWR comparator for one of our development.

I am giving supply of 3.3V to IC.

what I am observing is that , after giving input of 2.3 V or above at noninverting terminal, the output is getting clamped to 3.3V.

Is it rail to rail device?

How much max input need to be given to get operation ?

I have attached screenshot.

Kindly support

over 1 year ago

0 Michael Hawkins over 1 year ago

TI__Intellectual 1320 points

Hi Sagar,

This part doesn't cover full rail-to-rail input where the input ranges from Vee to Vcc.

LM2903B covers from Vee to Vcc - 2V, which lis likely why there are functional issues with the noninverting terminal at 2.3V.

With this setup, max recommended input voltage for operation would be 1.3V.

From LM2903B datasheet:

Since this is a commodity part, some of our cheaper comparator options with full rail-to-rail input range, we have TLV1821 and TLV1701.

Best,

Michael

0 Paul Grohe over 1 year ago

TI__Guru 63366 points

Also see the LM393LV, a drop-in replacement with R-R inputs and low cost.

0 Sagar Nikam over 1 year ago in reply to Michael Hawkins

Prodigy 30 points

Hi Michael,

Thank you for response.

Is suggested TLV1822 and TLV1702 devices P-P matching with LM2903B?

0 Sagar Nikam over 1 year ago in reply to Paul Grohe

Prodigy 30 points

Hii Paul,

LM393LV device is P-P matching with LM2903B?

0 Michael Hawkins over 1 year ago in reply to Sagar Nikam

TI__Intellectual 1320 points

Hi Sagar,

TLV1822, TLV1702, and LM393LV are P-P with LM2903B.

Best,

Michael

0 Paul Grohe over 1 year ago in reply to Sagar Nikam

TI__Guru 63366 points

Hello Sagar,

Yes.

The LM393LV is meant to be drop-in improved performance replacement for the LM2903 when the supply voltage is 5V or less.

The main difference being that it is Rail to Rail input and does not have the Vcc-2V input voltage limitation.

+1 Sagar Nikam over 1 year ago in reply to Paul Grohe

Prodigy 30 points

Hii Paul,

Thank you for support.

Have a great day

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LM2903B: Query regarding performance limitation observed in this OP-amp device