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How can I distinguish between the "11-bit" ADS7951S and 12-bit ADS7951SB when looking at an actual chip?
I have the DBT package, and the markings are " ADS7951 87TG4 ECEN "
These may have been samples from TI, or they may have been purchased from Mouser. I've gone through about 14 now so I can't remember what was ordered each time and where they were sourced.
By the way, I have my custom boards with the ADS7951 working beautifully, thanks to excellent support here. Now that they're functioning, I'm trying to move on to the manufacturing stage and need to verify whether we've been testing 11-bit or 12-bit accuracy. We'd really like to get the lowest noise floor possible, so I'm sure it's rather important whether we're currently using the 11-bit and can look forward to some improvement, or if we're already using the 12-bit top-of-the-line parts.
Thanks for any help.
P.S. Before posting this question, I did look at the data sheet since I've seen some include details on markings and designations. However, it seems that the ADS7951 data sheet does not have this information anywhere.
Brian,
We're looking into this and will get back to you as soon as possible.
Brian,
Quicker results than expected...
If there is no grade marking on the device then it is a low-grade device (11 bits).
Topside Symbol : 30DBT-CYTG 01
+--------------------------+ \T/ = TI LOGO
! | ADS7951 ! YM = YEAR MONTH DATE CODE
!B | \T/ YMSG4 ! S = ASSY SITE CODE PER QSS 005-120
! O | LLLL ! LLLL = LOT TRACE CODE
+---------|----------------+
2<---------------- GRADE OUT CHARACTER TO BE ADDED
BEFORE PIN 2
O - PIN 1 (DIMPLE)
GRADE OUT CHARACTER MAXIMUM IS 1 CHARACTER
Topside Symbol : QFN4X4-CYTG 01
|<-- reserved for grade out letter
+------------|----------+
! O | ! TI = TI LETTERS
! ADS | B ! YM = YEAR MONTH DATE CODE
! 7951 |__________! LLLL = ASSY LOT CODE
! TI YMS ! S = ASSEMBLY SITE CODE PER QSS 005-120
! LLLL !
+-----------------------+
O - PIN 1 (MARKED)
Hi Kevin,
So, if I interpret the ASCII drawings correctly, the ADS7951SB parts will have "ADS7951" in the upper right and "B" on the middle left, at least for the DBT package that I have used in my design.
While I'm confirming the above, can you tell me whether the grade out character is of the same ink and font as the rest of the markings?
In contrast, the 10-bit and 8-bit parts do not have a grade out character at all, but rather are designated with a different part number, e.g., ADS7955 (10-bit) and ADS7959 (8-bit). As a minor related question, are the 10-bit and 8-bit parts really just 12-bit parts that are graded even further below 11-bit?
Brian,
Your interpretation of the ASCII art seems to be accurate. I've not actually looked at one of these devices myself so I can't say for sure where it is. I expect that the silkscreen uses the same font/ink to mark the grade out character.
The 10-bit and 8-bit members of this family are actually different parts, not 12 bit devices that do not meet grade requirements. Your '11 bit' device still outputs 12 bits of data - just the INL/DNL specs create missing codes to make the device effectively 11 bits.