I want to readout the TMP121 every 1 second and I want to verify if my approach is correct when going for low power use. In order to do this I'm missing relevant information from the datasheet so I will first do some assumptions in the form of questions. Can you tell me if these assumptions are correct?
1) a New conversion always starts when CS_N becomes inactive (high)?
2) The TMP121 has an internal timer that is triggered on CS_N becoming inactive which is also used for automatic periodic conversion?
3) You do not need to wait for the maximum trigger period (640ms) to start a new conversion manually. Therefor the minimum conversion period (not conversion time) can be around 320ms conv time (maximum) + spi readout time 1u6s (minimum)
So for a low power readout at 1Hz intervals with e.g. sck at 5MHz I would do:
1) reset value of CS_N = low
2) activate CS_N to start conversion
3) deactivate CS_N after 320ms to stop conversion and start readout + start analog shutdown timer
4) keep CS_N low to force shutdown until analog shutdown timer is 1s - 320ms = 680ms
5) repeat from 2)
Does this seem correct or am I missing something?
Sander Ter Burg