LTC6811 & LTC6813 - work with different frequency conversion

Thread Starter

Lorenzo Ruscitti

Joined Nov 12, 2018

I am using the LTC6813 and LTC6811 in parallel. I would like to set a different conversion rate for GPIO and Cells. When I set it differently, what I get is a PEC error, but when I set them the same no. Can help me understand?
I have three SPI chains and every chain at 4 ltc in daisy chain. For the communication, I set REFON to 1 soak the delay to wake it imposed only for the first ltc of each chain. In addition, as illustrated in the date sheet, from the time tables, I am going to calculate the time needed for the conversion controls, so that I can read cells and gpio without any error, this has worked using conversion frequencies of 1k for both controls.I have already implemented the whole system and have implemented adcv and adax controls. I have always used the conversion rate of 1k for both controls and everything has always worked properly. Now I need two values, the MD of the frequency parameter, different for the two controls. What I get is an error in the reading of cells and gpins. Moreover, I tried to add the command tostat here too I have the same problem. In addition, the problem of the pec error in reading is NOT present, in the case of a different MD parameter, if I no longer include the delay that I have calculated.

to explain better my situation.
I set REFON bit to do the conversion more quickly, as written on the attached image.
So I only provide a delay, equal to trefup as shown in the attached state diagram. Then the REFUP state procedure says that if a valid command is received it goes to the MEASURE state. Once the measurement is finished, if the REFON bit is 1, as in my case, I will return to the REFON state. Then if a valid command is not sent for a time equal to tsleep, based on the HW DTEN pin, I can be in the SLEEp or EXTENDED BALANCING state. I have measured the DTEN pin on the board and I have seen that it is at GND, so I should go to the SLEEP state. But from the state diagram not only the DTEN pin is taken into consideration but also WD TIMEOUT, but what would WD TIMEOUT be? How do I check its status?

thank you