What does the last (18th) character denote in the MFR# number on my packaging label?
The last character in the MFR# is for internal Cypress use and has no meaning for customers.
The sample packaging label shows two numbers and a bar code. The first number is the 17-character Ordering Part Number (OPN) that is specified in the datasheet for the Cypress part. The second number is the Manufacturing Part Number (MFR#) which consists of the OPN plus an additional character. The last (18th) character is a code that is used for Cypress’ internal tracking purposes; it has no meaning for the recipient. The 18th character has no bearing on the form, fit, function, and operation of Flash, and has no impact on the options selected by the OPN. When ordering Cypress products, the 18th character is not required. Although the MFR# may be found on associated documents, labels, and so forth, the MFR# is not stamped on the chip.
Here are sample MFR#s for three different OPNs:
S25FL116K0XMFI043Z (MFR# = OPN + Z)
S29AL016J70TFI010A (MFR# = OPN + A)
S29JL032H70TFI320H (MFR#= OPN + H)