LMV7239: could this socket support 2MHz application?

Hi Chi,

could work under ideal conditions:

chi_lmv7239.TSC

But the concrete performance depends on many other factors like supply voltage, common mode input voltage, supply noise, signal noise, etc. Eventually, adding hysteresis might be necessary.

Can you show a schematic?

Kai

Hello Kai,

Thank you for your quick help on this thread :) 

Hello Chi,

Thank you for your question. I would like a little more information about the details of your use case. 

Can you provide a schematic and the voltage levels of the input signal? This way I can better understand the design parameters that Kai mentioned.

kai klaas69 said:

supply voltage, common mode input voltage, supply noise, signal noise, etc

Best Regards,

Joe

Applications Engineer

Linear Amplifiers Business Unit | Comparators Product Line (CMPS)

All information in this correspondence and in any related correspondence is provided “as is” and “with all faults”, and is subject to TI’s Important Notice (http://www.ti.com/corp/docs/legal/important-notice.shtml)

Hi, Kai and Joe

here is more inputs, supply voltage is 3.3V, noise is 20mV. input signal is single-end +-1.5V 2MHz, bias is 300mV. output is 3.3V LVCOMS

BR,

Chi

Hi Chi,

Thank you for providing more information. From what I gather, your input signal will swing from -1.2V to +1.8V for a total 3V swing? I am not sure what you mean by the bias is 300mV.

Assuming that your 20 MHz input signal is close to 50% duty cycle, you can AC couple the input (IN+) and set the common mode voltage with a resistive divider.

Best Regards,

Joe

Applications Engineer

Linear Amplifiers Business Unit | Comparators Product Line (CMPS)

All information in this correspondence and in any related correspondence is provided “as is” and “with all faults”, and is subject to TI’s Important Notice (http://www.ti.com/corp/docs/legal/important-notice.shtml)

Hi，Joe

actually, customer use case is shown like below

BR

Chi

Hi Chi,

Thank you for providing that info.

AC coupling the input to IN+ should work for your application so long as the input signal is 50% duty cycle. Just to confirm, is this the case?

Best Regards,

Joe

Applications Engineer

Linear Amplifiers Business Unit | Comparators Product Line (CMPS)

All information in this correspondence and in any related correspondence is provided “as is” and “with all faults”, and is subject to TI’s Important Notice (http://www.ti.com/corp/docs/legal/important-notice.shtml)

Hi, Joe

yes, it is the case using AC coupling in IN+ and duty cycle is 50%.

in my understanding, IN+ have +1.5V to -1.5V voltage range, it will be over our supply range 3.3V, it still will work? or using resistor divider in IN+ to decrease the -1.5V in IN+

BR

Chi

Hi Chi,

Your application will work if you AC couple the inputs and set your bias voltage of the resistive network to 1.5V.

This would result in your input swinging from 0V to 3.0V.

After doing this, the threshold has to be increased to 1.5V or 1.8V if you would like that 300mV bias you mentioned.

Please let me know if you need further explanation or clarification.

Best Regards,

Joe

Applications Engineer

Linear Amplifiers Business Unit | Comparators Product Line (CMPS)

All information in this correspondence and in any related correspondence is provided “as is” and “with all faults”, and is subject to TI’s Important Notice (http://www.ti.com/corp/docs/legal/important-notice.shtml)

Hi Chi,

what is the signal shape? Square wave? Or sine wave?

Kai

Hello Kai,

From the image that Chi provided, the input looks to be a square wave. 

Chi,

Please reach out if you need further explanation on this. 

Best Regards,

Joe

Applications Engineer

Linear Amplifiers Business Unit | Comparators Product Line (CMPS)

All information in this correspondence and in any related correspondence is provided “as is” and “with all faults”, and is subject to TI’s Important Notice (http://www.ti.com/corp/docs/legal/important-notice.shtml)

Hi, Joe and Kai

Thanks a lot for your test result and support, I will update to my customer and any question will keep you posted, thanks

BR

Chi

Hi Chi,

Thank you for the update. I will wait for your feedback.

Best Regards,

Joe

Applications Engineer

Linear Amplifiers Business Unit | Comparators Product Line (CMPS)

All information in this correspondence and in any related correspondence is provided “as is” and “with all faults”, and is subject to TI’s Important Notice (http://www.ti.com/corp/docs/legal/important-notice.shtml)

Chi

Sorry for the follow up on this.  We just don't like things to go too long without a response.

Are you still waiting for feedback or can we close this post as resolved?

Chuck

Hi, Chuck

customer has accepted this solution, and didn't have any more question so far.

Thanks a lot for your help

BR

Chi