MSP430F5659 backup battery circuit

Did you try to read User's Guide? http://www.ti.com/lit/pdf/slau208

It contains quite well-written chapter about Battery Backup System

Leo Hendrawan TI said:

i agree with you, it is not really clear on how to do the battery backup

Leo,

Actually what I am missing in TI datasheets - typical system configuration circuits (all but gpio/peripheral pins) which would answer such kind of questions out of the box. For example check any datasheet of any AD microcontroller and you will see.

Hi Ilmars,

that is a good feedback. For MSP430, what i can think of is just to refer to the Hardware Tools User's Guide which contains the schematic of our development kits. It can be used as the reference for typical configuration circuit you mentioned.

I will try to forward this info to the team in charge for the documentation.

I know that many datasheets from othe rmanufacturers contain typical application schematics or test circuits. However, those are usually stand-alone all-in-one papers. TI's philosophy is to split device specific information from generic information.

This way, an update of the users guide is done in one document for all MSPs of that family. You won't get orphaned datasheets with outdate information for older devices.

And things like the backup circuit are published as whitepapers or application notes. (of which TI publishes way more than any other company, because they too apply to multiple devices)

It is an unusual approach, but one I like.

Jens-Michael Gross said:

And things like the backup circuit are published as whitepapers or application notes. (of which TI publishes way more than any other company, because they too apply to multiple devices)

It is an unusual approach, but one I like.

Nothing against User's Guide / datasheet approach. It's good.

BTW before posting - did you find appnote/whitepaper regarding backup circuit you mention?

I strongly disagree to approach "check all application notes and whitepapers that possibly have circuit you look for". Are you serious? Really?

Also I would like to remember that there is good "typical application circuits" article with lot of circuits but... it's outdated (grin):

http://www.ti.com/general/docs/litabsmultiplefilelist.tsp?literatureNumber=slaa024

Ilmars said:

strongly disagree to approach "check all application notes and whitepapers that possibly have circuit you look for".

Why not? You don't have to go to the library and browse through gazillions of printed documentations anymore.
And if there is no reference implementation, then there is none, No matter whether it is not on the whitepapers/applications list or not in the datasheet.

Also, putting everything that is relateted around a versatile multi-purpose chip like the MSP430 into each datasheet would blow it up to Bible size.

Don't forget, one might think a battery backup reference design is a must-have, others want reference info about oscillator, others about hardware-debouncing pushbuttons etc. If you serve one, you'll have to serve all.

Usually, whenever I needed a reference design, the ones I found in the datasheets weren't suitable for what I wanted to do.

In the meantime, take a look at thenew TI Designs reference design library
It's just in its beginning stage, but already offerst a good deal of reference designs. Many more to come. Maybe a separate subsection can be added for partial designs like this one.

Leo's hint about the exp boards and the tools guide is a good one. The boards are perhaps not really reference implementations, but can be counted as a 'known working example', which is almost as good in most cases.

So please don't clobber the datasheets with gazillions of example circuits of what could be done how.

Jens-Michael Gross said:

So please don't clobber the datasheets with gazillions of example circuits of what could be done how.

I ask just one showing all but peripheral and I/O pins - power, xtal, decoupling and reset.

It is noticeable that you are TI advocate for some unknown reason, but please have common sense here.

Ilmars said:

I ask just one showing all

So a stripped-down experimenters board schematics? Well, most people wouldn't be able to extract the part they need from it then. And for the combination of multiple things, a different schematics needs to be designed for each individual MSP.

And without a proper explanation about why and how to do the PCB, it would be next to useless. So a huge work you're asking for. Just to spare a bit exercise with a search function.

Ilmars said:

It is noticeable that you are TI advocate for some unknown reason

Not really. But I think further than 'I want'. Things are as they are and changing them requires work. Lots of work in this case. For many things there are application notes and whitepapers. Requesting another one for a specific topic, that can be used fo rmore than one MSP, with explanations and considerations, seems a good way to handle this.
And of course linking it then to all the MSP product pages where it applies.

Jens-Michael Gross said:

So a stripped-down experimenters board schematics?

You have to search for it first. As you already noticed here in this forum - many who are doing "Make a switch" have problem with this. Perhaps you have to publish chapter of your book "how to read TI documentation" as leaflet ASAP :D

Ilmars said:

. Perhaps you have to publish chapter of your book "how to read TI documentation" as leaflet ASAP :D

That's really worth considering. But how are the puzzled people supposed to find it when they are already unable to find the other documentation? A hen-and-egg problem. :)

Accidentally stepped on datasheet SLAS554H which contains what I am asking for every msp430 datasheet (surprise!): typical application circuit (partially shown here):

I guess, it has been placed there because there is only one (well, now there are two) datasheets for the CC430 family, and this circuit is specific to exactly the MSPs in this datasheet and none else.

More precisely, teh circuit belongs to the radio core part and therefore is likely copied from the CC1101 datasheet.
After all, the CC430 parts are SoCs, fusing an MSP430 with a CC1101. So it's actually the CC1101 part of the datasheet that got the application circuit (adjusted to the CC430 package)

I agree that this is an anomaly, but this doesn't justify a demand to do it everywhere for everything too.

I also agree that it is nice to have application examples and typical circuits in a datasheet, but where to stop? You can add a hundred pages of circuits and still not cover everything. And this for each and every datasheet? Forget it! I'm already surprised how often TI updates the datasheets even for marginal changes. Others don't do an update for years. This would also happen for the MSPs when all this stuff had to be looked after.

Jens-Michael Gross said:

You can add a hundred pages of circuits and still not cover everything.

You are repeating yourself so I have to repeat my answer: no, I did not ask for hundred pages of circuits but one.

Jens-Michael Gross said:

And this for each and every datasheet? Forget it!

It was just suggestion. If TI and their advocates do not care to improve documentation and by any means try to prove that documentation is best you can have - it's not my problem actually. Maybe this is one of reasons I am switching MCU away from msp430 ;)

Ilmars said:

I did not ask for hundred pages of circuits but one

You ask for only one. And the next 99 people also ask for just one. Unfortunately this likely makes 100 different ones. Why serving your request, when serving all requests is not doable?

As I said, I understand your request and agree that it would be nice, but I also understand why it isn't done. And gave an explanation.

Gents,

great discussion around this topic, thanks for providing and discussing your first-hand perspective. We (TI) are actually in the process of making our device datasheets more useful/applicable and improve general alignment and consistency, and this applies across both the embedded and analog sides of our product offering. Believe me it is no small undertaking and changes will affect future products being released to the market more so than products that have already been released. Without going into too much detail at this point, what this will mean specifically for MSP430 is that there will be some general basic application circuit and layout information provided in the datasheets to help exactly with the fundamental connections for each "interface" the chip has that were discussed here. Think of the load cap circuitry and PCB layout for XT. Or the few passives and the connector needed to make USB work. Power supply and ADC decoupling. JTAG. And so on. The idea is definitely not to reproduce/duplicate a bunch of information but rather to give customers a good starting point and then link over to additional in-depth material as needed (for example, an XTAL oscillator best-practices app note, or a user’s guide chapter). We should see such improvements in datasheets for newly released products onwards from the middle or later this year.

Andreas
Applications Manager
MSP New Product Development