LM35DT/NOPB vs LM35DZ about 1 Celsius degree diference?

Other Hardware Sensors
1

Hi,

I have on same board two LM35 sensors, one is LM35DT the other LM35DZ.

The trouble is, they are one next to the other but still read different. And I mean about 1 degree difference.

Output of the serial:

Initializing...
Ready
LM35DT: 19.04
LM35DZ: 17.58

LM35DT: 18.55
LM35DZ: 17.58

LM35DT: 18.55
LM35DZ: 17.58

LM35DT: 18.55
LM35DZ: 17.09

LM35DT: 18.55
LM35DZ: 17.58

LM35DT: 18.55
LM35DZ: 17.58

LM35DT: 18.55
LM35DZ: 17.58

LM35DT: 18.55
LM35DZ: 17.58

LM35DT: 18.55
LM35DZ: 17.58

LM35DT: 18.55
LM35DZ: 17.58

LM35DT: 18.55
LM35DZ: 17.58

LM35DT: 18.55
LM35DZ: 17.58

LM35DT: 18.55
LM35DZ: 17.58

They are like 0.5cm apart, both with isolated pins, LM35DT conencted to A0 and the other to A1, 1 second delay between each sensor measurement.
If you read the datasheet they state differences in accuracy between A/C/D models; but they both are D model, just different packaging.

Wondeing if I buy the LM35AH model, would give a 3rd different value? Are they really that diferent in performances as they are in prices?

Thanks.

2

They're analog, so vulnerable to variations in the components in their two circuits and the datasheet says they're accurate to 0.5 degrees. Thus, not an especially surprising result.

3

Can you post the code?

  • what is the timing between the reads?
  • does it also occur when you change the order?
  • or the pins used?
  • is your power supply stable?
4

1 seconds between each read
it's same if I change the order
it's same if I change the input pins
it's powered fro USB and I don't think the power fluctuate with such a steady rate to match every reading

Seems that the bigger TO-220 package is more 'cool' that the other :slight_smile: