LMH6572: LMH6572MQX/NOPB

Hello Tony,

  Thank you for sharing the test report. A few questions:

1. What are the supply voltages applied to the device during the LiH test? 
2. Is this test measured by applying 2V at the Select or Enable pins and measuring current drawn via power supply as shown on page 7 of the test report? 
3. Are there any external passive components connected to the logic pins? 
4. Is this at both the Select and Enable pins of the device? 

Best Regards,
Sima 

Hi Sima,

Thank you for the feedback, after checking with our engineers and the testing laboratory. Here is the answer:

1, What are the supply voltages applied to the device during the LiH test?   (2V)

2, Is this test measured by applying 2V at the Select or Enable pins and measuring current drawn via power supply as shown on page 7 of the test report?  (YES)

3, Are there any external passive components connected to the logic pins?   (Without any external passive components connected)

4, Is this at both the Select and Enable pins of the device?  (YES)

Sima, we purchased twice the parts with different date codes (From TI and Mouser), and we tested them at two test centers, both have the same problem. We need your further suggestion, or should we return these to TI or Mouser for further testing?

Thanks.

Tony

Hello Tony,

  For the 1st question, I believe you gave me the voltage applied at the logic pins, but I was referring to the VS+ and VS- of the device (pins 12, 11, and 16).

   That is very strange that it failed the test; how many units did you purchase from TI and Mouser? Our next steps would be looking at a new device on our end, then if we confirm the correct value. We would ask for you to go through the return process. 

Thank you,

Sima 

Hello Sima,

Thank you for the fast response.

For the 1st question, they added +5V on pin 16, -5V on pin 11 and pin 12.

We purchased 66pcs from TI  in September 2021 and 66pcs from Mouser in June 2022, they are different date code and both of them were failed.

Yes, please arrange the test of the parts in your warehouse, I think this can help us find out the problem.

Could you advise how long will it take for you test the device on your end please?

Hello Tony,

  Thank you for the additional information!

  I have ordered a few units of the LMH6572MQX/NOPB to test; they should arrive at our lab by next week. 

Thank you,
Sima

Hello Sima,

Good day, have you got the units for testing? Please let me know once there have any updates. Thank you very much!

Hello Tony,

  Yes, I was able to test out the units, and I saw the exact same current reading you are getting on your end. The unit with no load and Vs+/- of 5Vs is showing a current of 31-32uA at both SEL and EN. I am going to test it out in a load configuration this week, and update you if that changes to the datasheet specified value. 

Thank you for checking in and your patience!
Sima

Hello Sima,

Good afternoon, is there any updates?

Best regards,

Hi Sima,

We haven't received your message in the past 10 days, is there any updates for our technical problem?

Please let me know. Thank you very much.

Hello Tony,

  I apologize for the delay here. Yes, I was able to test the unit in other configurations. The amplifier output loading of RL = 100Ohm as mentioned in the datasheet did not make a difference as expected. Current at both SEL and EN pins are still reading at around 32uA. I tested the device with a resistor at the enable and select pins which as expected did change the current readings. It looks like the device was characterized with a pull-down resistor at the enable and select pins. I am currently checking with our final test site since this is a measured specification before device distribution. 

Thank you,

Sima 

Hi Sima,

I hope you had a nice Christmas holiday!  Do you have a final conclusion or report for the question? If you suggest us not to use the parts due to the incompliance of the datasheet, should we return the parts back to Mouser/ TI?  

Thanks,

Tony

Hello Tony,

Sima will be able to respond with an update early next week.  Thank you for your patience!

Best,

Alec

Hi Sima,

Could you update your progress please?

Hello Tony,

I apologize for the delay; Sima is out of office and will be able to respond to you this coming Monday, January 9th.  I made a mistake when reviewing our team's holiday travel and I was off by a week when I wrote my prior response.  I know Sima will be able to help provide final resolution.

You may ask me any additional questions or for clarity of explanations in the interim.

Best,

Alec

Hi Sima,

It’s been a long time, is there any progress? Do you have a final conclusion or report for this case? If you suggest us not to use the parts due to the incompliance of the datasheet, should we return the parts back to Mouser/ TI?  

Hello Tony,

  I apologize I missed the earlier replies. We have located the final test boards/hardware. Since this device is part of the national semiconductor acquisition, we have been pushing for a location of their schematics. I believe these devices are testing at 30-35uA of current due to a different configuration used for test hardware rather than incompliance of datasheet since the samples I tested on site are showing similar values to your tests. 

   I will ping the team again for an update. Sorry again for the very long delay on finding the source of the issue. 

Thank you for your patience!
Sima 

Hello Tony,

  We have located the schematics. The configuration used for the test has a 50 ohm series resistor with a decoupling capacitor to a 2V voltage source. 

Thank you,

Sima 

Hi Tony,

only if the input currents IiL and IiH were higher than specified could be problematic, because then a chosen pull-up resistor scheme might no longer work. See figure 19 of datasheet. But smaller input currents IiL and IiH aren't problematic at all.

Kai

Hi Sima,

Sorry I can’t follow you, because our technical people is on holidays. 
In previous replies, it seems that we have the similar test values. You mean we should has add a 50 ohm series resistor with a decoupling capacitor to a 2V voltage source, then we can test the values compliance with the datasheet?

And your colleague Kai answered the question, he didn’t mentioned the schematics.

Could you put it simply, are these parts fully functional? We can use them according to the datasheet?

Thanks.

Tony.

Hello Tony,

  Yes, that is correct. There might be additional resistance as well in/post the jumper connections, but the resistance does change the value.

   Kai is correct; that this isn't an issue since these values are smaller. 

   Yes, the parts are fully functional and in compliance with datasheet. 

Thank you,

Sima 

Hi Sima,

I have forwarded your answer to our customer, they still have 2 questions:

1, If there should add a 50 ohm series resistor for the test, why the TI datasheet didn't mention this? Do you have the original paper of the National Semiconductor include  the schematics?

2, According the TI datasheet, Current at both SEL and EN pins are reading at around 32uA, not the 112uA.  Is that means we should add a 50 ohm series resistor when we use the parts?

Thank you,

Tony

Hello Tony,

1. The snippet of the schematic shared above is from the original national semiconductor test solution. The datasheet is the original datasheet, but was later edited/adapted to TI's guidelines. Specs would not have changed in this case. Thank you for letting us know about this concern! 
   
   
2. Agreed with Kai. This is not necessary, but you may include these in the final design. From test standpoint, the reading showing lower current is not a concern; it would have been if it was showing higher current then specified. 

Thank you, 

Sima