Homebrew PCBs

Thanks.

So you are suggesting using the "IS1" and "IS2" pins without any current 
sense resistor (internal or external). Is that correct?

Regards,

Ross

Herbert E. Plett wrote:

> don't get fooled by the title.
> the DS2761 chip has two voltage inputs, one resolves 15uV in +-32mV 
> (direct
> connection of thermocouple up to 500C) and the other resolves 4.8mV in 
> 2-5V
> range (good for a pot input). on top of this it measures it's own 
> temperature
> and has an i/o pin (plus a switch sensor).
> the setup is very simple: the thermocouple goes to a screw terminal 
> close to
> the chip (isothermal) and the chip goes to one pin of the uC. the uC 
> doesn't
> even need a crystal, so the most expensive parts are the ref pot, the 
> relay,
> the power supply and other stuff you may add (LCD...), BTW all of this 
> also
> needed with an analog design.
> the algorithm is also basically simple:
> read the internal temp
> read the uV input and scale to temp units
> read the V input and scale to temp units
> compare V to uV+T and make the on-off decision (the actual control 
> algorithm)
> set the relay accordingly
> repeat once a second...
>
> works like a charm, but I do only on/off (thermostat). an 
> 'intelligent' control
> algorithm is out of my scope as I have no (mathematical) control theory
> background.
> some smart procedure can be implemented to input the profile using 
> switches for
> command sequence and the pot for values if you want a stand-alone 
> control w/o a
> PC link.
>
> --- Ross McKenzie <valusoft@... 
> <mailto:valusoft%40optusnet.com.au>> wrote:
> > If I am reading it correctly, the DS2761 is a "High-Precision Li+
> > Battery Monitor". The datasheet says that its voltage measurement
> > channel does so with a resolution of 4.88 millivolts resolution. 
> Typical
> > thermocouples have a resolution of around 40 to 50 microvolts per 
> degree C.
> >
> > So obviously I am missing something from your description below. Could
> > you elaborate please?
>
> __________________________________________________
> Do You Yahoo!?
> Tired of spam? Yahoo! Mail has the best spam protection around
> http://mail.yahoo.com <http://mail.yahoo.com>
>
>