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Topic: my first big project - BMS - is it possible? (Read 10 times) previous topic - next topic


ok, lets see if I got this right;

This chip turns 4 arduino outputs into 16 outputs on the chip, by combining different high/low inputs on the chip (4X4 combo's=16), right?

are these outputs strong enough to open/close small relays without an additional power source? I looked at the datasheet again, but there are just too many damn numbers :)


The chip will be a lot easier to use than the MAX chip and basically fool proof WRT only having a single output active.

You tie the  latch pin to 5v and apply four signals to the A, B, C, and D inputs. The binary pattern applied to this inputs determines the active output.

Couldn't be simpler, and 0 chance of two outputs being active at the same time.

The 4515 only has 16 outputs and the MAX has 20, if you need > 16 you can use 2 or more 4515s.

Rob Gray aka the GRAYnomad www.robgray.com


I looked at the datasheet of the 4514 decoder chip  http://media.digikey.com/pdf/Data%20Sheets/Fairchild%20PDFs/CD4514BC_4515BC.pdf
but it's too technical for me.
is this chip to replace the MAX chip, or what?
can you explain a little?


Thanks for the advice.
I understand the concern, and it s certainly something Ill remember.
I could incorporate a check if voltage ==0 after opening the last and before closing the next relay.

For security reasons, i plan to test the system on a much smaller 20 cell nimh pack.

I have no idea what the 4514 decoder chip is/can do, but Ill look in to it.


Oct 24, 2011, 09:58 am Last Edit: Oct 24, 2011, 10:02 am by Graynomad Reason: 1
it seems pretty straightforward to me;

Yes it is, just be mindful of the consequences if for whatever reason you open one relay before closing the another.

For example how will you know that relay 1 has actually closed before you open relay 2?

What if there's a mechanical failure in relay 1 and it sticks open, if you then open relay 2 it's goodnight nurse to half your circuit and with the resultant fire maybe the vehicle as well.

Do you trust your coding ability to that extent?

If you use a 4514 decoder chip it's not possible to have > 1 output active at a time which at least takes your code out of the equation, not mechanical failure though.


Rob Gray aka the GRAYnomad www.robgray.com

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