I've been experimenting a while with an LM92 temperature sensor:
http://cache.national.com/ds/LM/LM92.pdf
And I'm a bit dissapointed, is it normal that a sensor with 0.33°c
accuracy and a resolution of 0.0625 °C has its lower 2 to 3 bits jumping
around? Resulting in a 0.2°C jumpy display? I would have thought it
would be more stable than that? Or am I missing something?
I have the lm92 connected as followed :

SDA & SCL with a 4k7 pull up to a PIC
T_CRIT and INT connected to a 10K resistor to V+
A0 and A1 to V+
V+ = 5v
22nF over V+ and GND

On 2008-05-27, Jurgen Priem <jurgen.//NO//SPAM//priem at (no spam) pandora.be> wrote:
I've been experimenting a while with an LM92 temperature sensor:
http://cache.national.com/ds/LM/LM92.pdf
And I'm a bit dissapointed, is it normal that a sensor with 0.33°c
accuracy and a resolution of 0.0625 °C has its lower 2 to 3 bits jumping
around? Resulting in a 0.2°C jumpy display? I would have thought it
would be more stable than that? Or am I missing something?
I have the lm92 connected as followed :

SDA & SCL with a 4k7 pull up to a PIC
T_CRIT and INT connected to a 10K resistor to V+
A0 and A1 to V+
V+ = 5v
22nF over V+ and GND

22nF capacitor for power supply decoupling might me insufficient, try 100nF
or 220nF instead.

Is +5V supply voltage stable and clean? Is the supply of microcontroller properly
decoupled? Poorly decoupled microcontroller could introduce disturbance to
supply voltage. You might try to add LC-filter (ferrite bead + small
capacitor) in the power supply of microcontroller and/or temperature sensor.


Decoupling the sensor with a series resistor from V+ to a big capacitor

Hi all,

I've been experimenting a while with an LM92 temperature sensor:
http://cache.national.com/ds/LM/LM92.pdf
And I'm a bit dissapointed, is it normal that a sensor with 0.33°c
accuracy and a resolution of 0.0625 °C has its lower 2 to 3 bits jumping
around? Resulting in a 0.2°C jumpy display? I would have thought it
would be more stable than that? Or am I missing something?
I have the lm92 connected as followed :

SDA & SCL with a 4k7 pull up to a PIC
T_CRIT and INT connected to a 10K resistor to V+
A0 and A1 to V+
V+ = 5v
22nF over V+ and GND


I'm trying to build a reasonably accurate ambient air sensor, i've tried
using an LM35 but gave this up because of the difficulty to get a good
linear amplification to boost the signal to a usable level for A/D and
thought a digital sensor would be the best option...
Anybody got a better idea for a sensor that has got a good accuracy, not
to pricy and has good availability or can fix my LM92 problem?

Thanks!
why don't you simply average the readings. that will smooth it out.

Hi all,

I've been experimenting a while with an LM92 temperature sensor:
http://cache.national.com/ds/LM/LM92.pdf
And I'm a bit dissapointed, is it normal that a sensor with 0.33°c
accuracy and a resolution of 0.0625 °C has its lower 2 to 3 bits jumping
around? Resulting in a 0.2°C jumpy display? I would have thought it
would be more stable than that? Or am I missing something?
I have the lm92 connected as followed :

SDA & SCL with a 4k7 pull up to a PIC
T_CRIT and INT connected to a 10K resistor to V+
A0 and A1 to V+
V+ = 5v
22nF over V+ and GND


I'm trying to build a reasonably accurate ambient air sensor, i've tried
using an LM35 but gave this up because of the difficulty to get a good
linear amplification to boost the signal to a usable level for A/D and
thought a digital sensor would be the best option...
Anybody got a better idea for a sensor that has got a good accuracy, not
to pricy and has good availability or can fix my LM92 problem?

Hi all,

I've been experimenting a while with an LM92 temperature sensor:
http://cache.national.com/ds/LM/LM92.pdf
And I'm a bit dissapointed, is it normal that a sensor with 0.33°c
accuracy and a resolution of 0.0625 °C has its lower 2 to 3 bits jumping
around? Resulting in a 0.2°C jumpy display? I would have thought it
would be more stable than that? Or am I missing something?
I have the lm92 connected as followed :

SDA & SCL with a 4k7 pull up to a PIC
T_CRIT and INT connected to a 10K resistor to V+
A0 and A1 to V+
V+ = 5v
22nF over V+ and GND


I'm trying to build a reasonably accurate ambient air sensor, i've tried
using an LM35 but gave this up because of the difficulty to get a good
linear amplification to boost the signal to a usable level for A/D and
thought a digital sensor would be the best option...
Anybody got a better idea for a sensor that has got a good accuracy, not
to pricy and has good availability or can fix my LM92 problem?

Thanks!