LM293A: LM293A FA

user5102208

Part Number: LM293A

Hi all,

One of my customer met the failure problem of LM293A, Pls help solve the problem and give some suggestion!

The problem they met was :the output voltage dive to 1.92V (under the normal condition the output is about 5V ) after the using for a period time, They measured the resistance between the pin 7and the pin GND is 9.8KΩ，and they suspected the chip was broken down!

The design schematic as follows:

could you help analyze the reason and give some suggestion??

BR!

over 5 years ago

0 Chuck Sins over 5 years ago

TI__Mastermind 23425 points

Please provide values for all the components in the circuit.

Thanks

Chuck

0 Chuck Sins over 5 years ago in reply to Chuck Sins

TI__Mastermind 23425 points

Since there has been no further update for a while, I am closing this post. If you have further questions, feel free to reply and the post will be re-opened.
Chuck

0 user5102208 over 5 years ago in reply to Chuck Sins

Intellectual 820 points

HI,

Sorry for mu late! I update the schematic here!

looking forward to your reply!

0 kai klaas69 over 5 years ago in reply to user5102208

Guru 140200 points

Hi,

eventually, U3B is oscillating. Remove C23.

Kai

0 user5102208 over 5 years ago in reply to kai klaas69

Intellectual 820 points

Hi Kai,

Thanks for your reply! At the same time , I wonder what can cause the failure mentioned above?

could you show me the most probable cause of it?

Thanks again!!

0 kai klaas69 over 5 years ago in reply to user5102208

Guru 140200 points

Hi,

as I already said, I think that the circuit is oscillating. This can often be observed when mounting a "filter" cap at the +input of comparator and at the same time using a feedback resistor to the +input to form a hysteresis.

I would check the output voltage U3B by the help of a scope. This will show whether there's an oscillation or not.

Kai

0 Chuck Sins over 5 years ago in reply to kai klaas69

TI__Mastermind 23425 points

Thanks Kai

Amplifiers

Amplifiers forum

LM293A: LM293A FA