I am using a msp430F5342 for a design and the band gap generator temperature sensor output seems to ramp up over a period of time after reset.
Is this normal (period is over 15 seconds) it appears to be related to how many times the A2D reads the sensor. (observation no actual proof of this). This seems rather baffling behavior. I didn't see anything in the errata so if anyone can elucidate what I am doing wrong let me know.
The real issue this causes is in order to reduce the jitter from the temperature sensor from giving noisy values, I'm running it through an IIR filter, unfortunately when it ramps like that it creates a large impulse that takes a while to clear from the filter. The real question is how can I predictably read temperature sensor output and know when its stable (not migrating due to the REFGEN being turned on)? Does this have to do with the reference buffer in any way?
Secondly I remember seeing a rather nice application note for using the calibration data in the TLV information stored on the device for computing the temperature. I have search fruitlessly through TI's web site and have unable to rediscovered it (hopefully I didn't just imagine it). (IE MSP430 TLV temperature sensor calibration doesn't yield any actual APP note results). Anyone have a reference too this (or even recall what it might be?)