PCF2127 RTC RAM does not work

取消
显示结果 
显示  仅  | 搜索替代 
您的意思是: 
已解决

PCF2127 RTC RAM does not work

跳至解决方案
1,974 次查看
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 项奖励
1 解答
1,933 次查看
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.

在原帖中查看解决方案

0 项奖励
6 回复数
1,613 次查看
tkhansen
Contributor I

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

0 项奖励
1,965 次查看
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?

 

1,954 次查看
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 项奖励
1,944 次查看
guoweisun
NXP TechSupport
NXP TechSupport

 

Do you mind to share with us your schematic?

 

0 项奖励
1,934 次查看
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 项奖励
1,957 次查看
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 项奖励