While trying to build a interface for a gps board to pc serial port, being pointed in the direction of using the maxim max710 5v dc-dc converter for the power control I've come to a stop.

ops: How would I find the value of a capacitor listed on a diagram as C1,C2,C4? I have read the data sheet over and over maybe I can't see the wood for the trees :shock:

The 710 has a shutdown and standby mode if the related pin receives a ground but what will happen if the 710 is supplying the power to the chip that gives the command to shutdown?

Also which would suit my interface better the typical operating circuit or the low-noise?

Hope the questions make sence as its pretty hard asking the right questions when your not sure what your doing

the data sheet for the items Im using.

http://pdfserv.maxim-ic.com/arpdf/MAX710-MAX711.pdf
http://pdfserv.maxim-ic.com/arpdf/MAX221.pdf

paul

 

The shutdown will still work provided power to the signalling IC last for a short time even after MAX710 has gone into shutdown. This can be done with a low-drop diode and a medium sized (around 100uF) capacitor attached to the supply pin of signalling IC.

The type depends on condition of the place where you are going to put your receiver. If its an industrial environment with lots of transmission line running around or high power transmitters located nearby, it is advisable to use low noise design.

Regarding capacitor values, they are given on page number 8 figure 2b and also a table for components selection is given on page 10 (table 2).

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"There is no way to peace, peace is the way!"

 

Thanks for that Kinjalgp,

Thought It would have been different capacitor cos of the different configuration. It's a newbie thing

One quick question if a capacitor needed is a 100uF 16v tantalum type does it mean the circuit will only work with that type or could you use any 100uF 16v capacitor.

Paul

 

Well, even electrolytic would do in place but since Tantalum has better characteristics and has some advantages over electrolytics, it is recommended to use that one.

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"There is no way to peace, peace is the way!"

 

Just a correction.. You cannot always get away with using electrolytics in place of tantalums. Many ICs require their low ESR for stability, or else the circuit could be put into oscillation. Many voltage requlators call for these. Sometimes there are high performance electrolytics that can replace tantalums in many applications.

Steve

 

IMHO,

It is best to go with electrolytics with a lo ESR, as they are beter suited to applications of this nature( switching regulators.)

Tants have their place where lo leakage current is a requirement( as in timing circuits)
They are also used where space is at a premium ie high density layouts, although that said, electrolytics can be very small too.

Normal electrolytics, I generally use where they dont dont fall into the above categories.........

Just my 2 pennyworth :?

 

Thanks for the replys.

I did go for the electrolytics type capacitor and got the project up and running, with no smoke which was A bit of a suprise. Got quite a few unanswered thoughts still to learn, so no dout I'll be posting again.

Cheers Paul