LM293A: IN+ Exceed VCC

Francis Jiang

Part Number: LM293A
Other Parts Discussed in Thread: LM339

Tool/software:

Hi Team,

Customer ask what is the risk when IN+ exceed the VCC(VCC is 24V, and max IN+ is also 24V). As they don't have extra time to do the modification, so need to evaluation the risk based on this condition.

BRs,

Francis

over 1 year ago

+1 Clemens Ladisch over 1 year ago

Guru 318050 points

This is allowed by the absolute maximum ratings, so the device will not be damaged.

Input voltages above 22 V are outside the valid input voltage range, so the output might not be correct. (See sections 5.7 and 5.8 of the LMx93 application note to see what actually happens in that case.)

+1 HO SIU over 1 year ago in reply to Clemens Ladisch

TI__Genius 12015 points

Hi Francis,

The LM339 family has "fail-safe" inputs, which means that the inputs can go up to 36V independent of supply without damage to the device. Please read section 2.3 of this application's note: Comparator Input Types (ti.com)

As Clemens said, the output may be incorrect based on different input conditions since the input common-mode range can be violated. Page 21 of the datasheet shows input and output conditions:

0 Francis Jiang over 1 year ago in reply to HO SIU

TI__Expert 3490 points

Hi HO,

Thanks for your reply, customer would like to know more about the details of incorrect behavior and the internal principle. They want to directly talk with you. Please let me loop you in email, thanks.

BRs,

Francis

0 Francis Jiang over 1 year ago in reply to Clemens Ladisch

TI__Expert 3490 points

Hi Clemens,

Thanks for your reply, you are enthusiastic.

BRs,

Francis

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LM293A: IN+ Exceed VCC