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Topic: Data sheet querry Max 3485e (Read 961 times) previous topic - next topic

jonisonvespa

Apr 20, 2013, 04:14 pm Last Edit: Apr 20, 2013, 04:20 pm by jonisonvespaa Reason: 1
im hoping to use this max 3485e, due to my supply being slightly on the low side due to cable resistance, ive got 4.7v to play with.

one end in going to use a max 485e, other end max 3485e

am i right in thinking the supply for the max3485 can be max 7v, the data sheet contradicts itself  

vcc absolute max 7v,  or vcc 3.3v +-0.3v

cheers

data sheet

http://datasheets.maximintegrated.com/en/ds/MAX3483E-MAX3491E.pdf


strykeroz

Hi

It isn't really contradicting itself though I appreciate at first look it might appear to.

On page 1 it states the supply voltage should be 3.0 to 3.6V.  Then it states the absolute maximum, with the note that this is where permanent damage will start to occur.  Below that in the table of electrical characteristics it simply states those values are for where supply voltage is in the range VCC = 3.3V ±0.3V so that means when the device is in its typical operating range (3.0 to 3.6V as per page 1) you can expect those values.

So aim for 3.0 to 3.6 based on that datasheet.

Cheers ! Geoff
"There is no problem so bad you can't make it worse" - retired astronaut Chris Hadfield

jonisonvespa

#2
Apr 20, 2013, 04:32 pm Last Edit: Apr 20, 2013, 04:37 pm by jonisonvespaa Reason: 1
hi geoff thanks for the help, so im fine supplying vcc with 4.7v

i do realize its maby lazy / not best practice to add more circuitry to get it down to 3.3v, but if it works fine at 4.7v great

cheers

strykeroz

Hi,

For the sake of well under a dollar inc capacitors I'd put a small linear voltage regulator in there.  Though with your 4.7V supply that would need to be a low dropout voltage type.

I'm not sure if that's best practice either, but I always try to be conservative as I'm sure if everything is running down the middle of their design spec then I only have to debug mistakes I've made in the design or code.

YMMV of course, Geoff
"There is no problem so bad you can't make it worse" - retired astronaut Chris Hadfield

jonisonvespa

#4
Apr 20, 2013, 05:19 pm Last Edit: Apr 20, 2013, 05:22 pm by jonisonvespaa Reason: 1
yup you correct of course geoff i will be adding a reg and c's, 
thanks for the advice

jonisonvespa

how about using just a 3.3v zenner diode and a 100nf c for de-coupling that would do it, one less component?
cheers

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