Problem: National LM4040 frequently does not meet specifica

[JayW]

http://www.national.com/pf/LM/LM4040.html

We've been using these in many of our designs for awhile now - we're using
the .1% -A SOT-23 part. I'm curious if anyone has noticed that many of
these parts do not meet National Semiconductors specification? For one
thing, the operating current is listed from 60 ľA to 15 mA, yet I've found
that if you don't sink at least 5mA or so, they regulate very poorly (if
at all). In addition, I'd say that at least 40-50% of the devices don't
meet their accuracy specification. For example, I just did a small lot
size test of 5 brand new 2.500V .1% parts - and the results are listed
below:

Device # | Voltage |
1 | 2.500852 |
2 | 2.500104 |
3 | 2.507535 |
4 | 2.501194 |
5 | 2.513967 |
| |
| |

The maximum amount this devices should be off is 2.5mV, yet as you can
see, Device 3 is off 7.5mV and device 5 is off by almost 14mV for a
40% failure rate. Has anyone else seen this problem with these parts?

Thanks for any light you can share with me.

[To reply by email, "pull" the TRIGGER.]

 

[Al]

In article <2ul7u0d5d55p5ksk60agum5cljskkkf2vd@4ax.com>,
JayW <jwalling@comarkcorp.TRIGGER.com> wrote:

http://www.national.com/pf/LM/LM4040.html

We've been using these in many of our designs for awhile now - we're using
the .1% -A SOT-23 part. I'm curious if anyone has noticed that many of
these parts do not meet National Semiconductors specification? For one
thing, the operating current is listed from 60 ľA to 15 mA, yet I've found
that if you don't sink at least 5mA or so, they regulate very poorly (if
at all). In addition, I'd say that at least 40-50% of the devices don't
meet their accuracy specification. For example, I just did a small lot
size test of 5 brand new 2.500V .1% parts - and the results are listed
below:

Device # | Voltage |
1 | 2.500852 |
2 | 2.500104 |
3 | 2.507535 |
4 | 2.501194 |
5 | 2.513967 |
| |
| |

The maximum amount this devices should be off is 2.5mV, yet as you can
see, Device 3 is off 7.5mV and device 5 is off by almost 14mV for a
40% failure rate. Has anyone else seen this problem with these parts?

Thanks for any light you can share with me.

[To reply by email, "pull" the TRIGGER.]

Note 5 says tested at 25C. Did you meet the temp spec?

Al