PCF2127 RTC RAM does not work

cancel
Showing results for 
Show  only  | Search instead for 
Did you mean: 

PCF2127 RTC RAM does not work

Jump to solution
1,971 Views
dave_harmonjr
Contributor III

I recently ordered 20 custom boards from a board house and 6/20 the RTC's (PCF2127) ram does not work. If I write to it, and then read back from it I get all 0's. On the other 14 boards I read back exactly what I wrote. The chips would have be initially ordered somewhere around mid to late 2019? I think. I noticed another post where someone had the same exact issue as me and there were some replies asking him to fill out a document to send in the chip for analysis.

I was wondering if there is any errata list for this chip? I could not locate it. They all are exactly the same firmware, circuits, components, produced side by side. Every other function of the chip seems to work fine. Seems really bizarre to have that many not work, but also have that many work as well with very simple circuitry and assembly.

One of the chips have this written on it:

"PCF2127T

AFF173

1                Q5

knD19202"

I attached a picture of the circuit schematic.

0 Kudos
1 Solution
1,930 Views
dave_harmonjr
Contributor III

I bought new chips and replaced all the ones on the bad boards and they all work now. Seems to just be a bad batch of chips from NXP to mouser from late 2019.

View solution in original post

0 Kudos
6 Replies
1,610 Views
tkhansen
Contributor I

We experience something similar, so I'm interested in knowing if you reached a solution or conclusion?

0 Kudos
1,962 Views
guoweisun
NXP TechSupport
NXP TechSupport

Two questions for you:

1: Do you test the fail and good boards by switching RTC parts?

2: Did you damage the chips in the process of making the boards?

 

1,951 Views
dave_harmonjr
Contributor III

I swapped the RTC on a good board to a bad board and the RTC RAM worked on the "bad" board. So it appears it is a chip related issue. I got the reflow temp profile. It is attached.

0 Kudos
1,941 Views
guoweisun
NXP TechSupport
NXP TechSupport

 

Do you mind to share with us your schematic?

 

0 Kudos
1,931 Views
dave_harmonjr
Contributor III

I bought new chips and replaced all the ones on the bad boards and they all work now. Seems to just be a bad batch of chips from NXP to mouser from late 2019.

0 Kudos
1,954 Views
dave_harmonjr
Contributor III

1. No. I will do that right now. Good Idea.

2. I asked the production board house for a report on their process for assembling these boards.

0 Kudos