Q: Dallas DS1216 phantom rtc

[dorkshoei]

I have what appears to be a very old Dallas DS1216.



Installed into it (piggyback) was a 8k x 8 SRAM.

There is a video on youtube (*1) which talks about hacking in an external 3V cell however mine is an older design.

Mine has no B, C,  D,  E variant marking on the pcb and the internal chip is DIP14, not DIP16.  There are two batteries potted into the underside but the wiring isn't the same as the DIP16 version.

Based on the datecode it looks like a 1986 part.   

The Dallas 1988 databooks I found online reference a DS1216,  DS1216C, DS1216E,  DS1216F.    The last (2011) Maxim datasheet which is what is commonly online references "SmartWatch RAM (DS1216B/C/D/H); SmartWatch ROM (DS1216E/F)"

My question (finally :-) Is the DS1216 without a suffix what is now referred to as the DS1216B? 

1: ]video on Youtube

[DrG]

I think that your chip has a 1986 date code. I also have one of those (purchased at that general time frame).



I am too lazy to look up all of the characteristics from that 1988 data book https://archive.org/details/bitsavers_dallasSemi988DallasDataBook_32183835/page/199/mode/2up?q=dallas+semiconductor&view=theater but you may be able to get an answer by doing such a comparison with later products.

My hunch is that the no-suffix chip gave way to the one's with a suffix and that the answer to your question is that they are not the same as a 1216suffix that you mentioned. Have to look at all those specifications, I guess and it may certainly be compatible with some of the thers. Again, laziness

In fact, I am too lazy to find out what that 'M' means on mine (maybe a country code??). Hopefully someone will come by that knows.

[dorkshoei]

Visually the later 1216[suffix] versions look different.   The chip is centered inside the socket rather than shifted to the left (like yours and mine).

If you read the first post, I already read that 1988 databook.  I suspect the [more modern] B variant will work for me.   Looking for confirmation.

[DrG]

Visually the later 1216[suffix] versions look different.   The chip is centered inside the socket rather than shifted to the left (like yours and mine).

If you read the first post, I already read that 1988 databook.  I suspect the [more modern] B variant will work for me.   Looking for confirmation.

I did see that you went to the 1988 data book and I went there after reading that and included the link so that others might be interested in checking it out. Can you see any differences in the specifications for the no-suffix and the B (in the 2011 data book)? You may be right but I can't confirm that, I really just wanted to see if I could find mine

Is M for 'Malaysia" by any chance? I doubt it is for military grade as I am sure I bought it from Jade or from somewhere advertising in the back of Byte.

[dorkshoei]

I suspect the [more modern] B variant will work for me.   

I purchased 3x 1216B.  1987 date code.

Two read > 3.2V.  One read 2.6-2.8V.

I installed one of the 3.2V without hacking an external cell and it worked fine.

They appear to be genuine NOS, not Chinese pull/remark (which all have a more modern datecode and label).

It's interesting as the latest datasheet claims that they ship with the internal batteries disabled and that the battery is only enabled when Vcc on the outer DIP24 package exceeds the internal battery voltage.

Based on this I was expecting the three I purchased to read 0V until external power was applied but that was not the case.

So, either they have been previously powered on,  or the datasheet refers to a newer version of the chip (the current datasheet  ~2010 is based on an internal DIP 1315 phantom chip)

[DrG]

....
It's interesting as the latest datasheet claims that they ship with the internal batteries disabled and that the battery is only enabled when Vcc on the outer DIP24 package exceeds the internal battery voltage.

Based on this I was expecting the three I purchased to read 0V until external power was applied but that was not the case.

So, either they have been previously powered on,  or the datasheet refers to a newer version of the chip (the current datasheet  ~2010 is based on an internal DIP 1315 phantom chip)

The 1988 data book does have text about the "electronic seal" (p.617):

A major concern is how to Identify that a battery has full capacity, particularly when batteries are subject to uncertain handling conditions. The SmartBattery has an “electronic seal” implemented with both chip technology and special packaging to ensure absolute freshness. The reset input (RST) causes the battery supply to be disconnected from Its pins so that no discharge occurs during storage, shipping and handling; therefore, battery life is maximized. Once reset, the SmartBattery is designed to remain in an off-state and then automatically reactivated when Vcc (+ 5 volts) is applied. Subsequently, the SmartBattery will become uninterruptable even if the +5 volts is removed.

The text, however, is in an application note that does not specifically contain the 1216 (at least that I noticed). Seems that they had that technology at about the time the chips were made for sure, but it is not clear to me that it was used in the 1216.