AD8495 + K type amplifer + Arduino Leonardo

HI ,

i´ḿ currently working with the AD8495 in order to measure temperatures between 0-300 deg ( i used the configuration in the datasheet Figure 33 Page 14 : http://www.analog.com/media/en/technical-documentation/data-sheets/AD8494_8495_8496_8497.pdf )

Code :

float temp ;

void setup() { Serial.begin(9600); } void loop() { int raw = analogRead(A0); float Vout = raw * (5.0 / 1023.0); temp = (Vout-Vref)/0.005; Serial.println(temp); delay(500); }

But the problem is that i don´t know what´s Vref (voltage reference ) and how to choose it

Thanks

What is the voltage on Vref, pin 2? Is it connected to Gnd? Then Vref = 0, and VOUT = (TMJ × 5 mV/°C) + VREF or VOUT = (TMJ × 5 mV/°C) + 0 where raw = analogRead(VOUT) in your equations.

http://www.analog.com/media/en/technical-documentation/data-sheets/AD8494_8495_8496_8497.pdf

I know but i saw here : https://www.adafruit.com/products/1778 that they Added a TLVH431 1.25V precision voltage reference to the sensor ... that´s why i wonder if i really need this for my circuit .. i´m a little bit confused