RRH46410 Warm up time, warm up samples and suspend mode

Question

Hello everybody,
I have questions about RRH46410 sensor for IAQ applications.

In particular I want to use this sensor for wireless application, so power saving is important for my application.

In Ultra Low Power mode, after a warmup time of 15 minutes, do I need to discard first 10 samples to obtain valid measure data? This implies a total wait of 15+15 minutes, right?

If I want to put sensor is Suspend mode during idle phase and restart measurements after a certain time, do I need to wait 15 minutes of warm up again? It is not very clear from datasheet.

Thank you for your reply

IK_Renesas · Answer

Hello OmarGa , 
 Thanks for reaching out Renesas Engineering Community. 
 Apologies for coming little late to this. Well the RRH46410 is basically the ZMOD4410 with Renesas MCU. And the Renesas MCU is running internally the FW and the algorithm for the different operating modes, so that finally it can be easy for you to get the final measurement results through either UART or I2C interface. So basically what applies for ZMOD4410 the same also apply for RRH46410. 
 As you know the ZMOD4410 is a MOX sensor (also the RRH46410) so it's behavior is mainly based on the electrochemical properties of the MOX layer used. To be sure that the sensor is replying reliably you need to leave the sensor being working and powered-on for as long as possible. 
 In your case where you want to achieve low power consumption in any case you shouldn't power-off the sensor to stop the measurements and save current but we recommend to use the ULP (Ultra Low Power Consumption) operation mode which takes samples every 90 min. 
 As you can see below: 
 
 Here you can see how less the current consumption is when ULP operation mode is configured. 
 
 Also the sample rate: 
 
 So what we recommend to our customers is that if they want to save extra current they can put the MCU while this period 88990 ms to low power mode and disable the I2C and re-enable it when it is time to get the next measurement. 
 Keeping a delay between each start measurement 90 seconds it is very important with a max deviation 5% so that the algorithm is operating with the best possible accuracy. 
 
 Now as far it concerns the first warm-up time mentioned in the datasheet, please let me inform you that this is the warm-up time for which the sensor in case it powers-off for any reason, suspends the algorithm outputs (so the values measured by the sensor do not change until these 15 min elapse). 
 
 In general if the sensor powers-off , typically until it will start reporting again reliable measurements it needs 30 min. This is the typical start-up. 
 However if you leave the sensor powered-on for as long as possible and constantly working this period can be decreased to some minutes. 
 
 You can also refer to this FAQ: 
 https://en-support.renesas.com/knowledgeBase/20674448 
 
 So you can understand that even if you want to save current consumption in any case we do not recommend powering-off the sensor. 
 Because it is important to leave the sensor powered-on for as long as possible. 
 
 Hope these answer your questions. 
 
 Thanks and Regards, 
 IK