INDUSTRY 4.0  ANALOG DEVICES


a typical shelf life period and, if it cannot, what steps can be taken to preserve battery life before the patch reaches the end user.


DETERMINING BATTERY RUN TIME To accurately determine if the power supply solution meets battery life requirements, a load  simple representation of the load duty cycle of the system. For the remote patient monitoring patch we’re using, we’ll consider the three different operating modes that were previously presented: standard monitoring, temperature monitoring, and transmission modes. In standard monitoring mode, the current consumption of the patch shown in Figure 1  buck converter and the current draw of the MCU)    minutes. In transmission mode, the current draw  patch is transmitting data via BLE. These values can be found within the respective device data sheets by looking at active and quiescent current   calculation is determined using the time period for each operating mode during a day. Equation 1 is used, which gives us the duty cycles for our patch seen in Table 1.





Once each operating mode’s current consumption per day is found, the lifetime of the battery can be determined via Equation 3:


Here is a sample calculation: •  • Standard Monitoring Mode Current per Day 


 calculate the current consumption of the patch. Taking the active current consumption of each operating mode, the average current consumption per day can be approximated from 


• Temperature Monitoring Mode Current per  


•   Days


Here is a sample calculation: • Standard Monitoring Mode Current per Day = Standard Monitoring Mode Current × Standard Monitoring Mode Duty Cycle × 


• Standard Monitoring Mode Current =   Cycle = 0.9956


• Standard Monitoring Mode Current per  


16 March/April 2025 Irish Manufacturing


The results of these calculations show that the device will meet the 5 day runtime requirements with a battery life of over 5.1 days. This is deceiving, however, as this does not consider the shelf life of the system. In the medical device industry, it   


SHELF-LIFE CONSIDERATIONS Summing the shutdown currents of the devices in        time and a battery seal is required.


 the shelf will be severely diminished. Nearly    while sitting idle on the shelf. Inserting this battery capacity into Equation 3, a more accurate run time can be determined:  Monitoring Mode + Temperature Monitoring Mode + Transmission Mode) 


 While sitting on a shelf for over a year, the battery capacity is impacted by battery         


  


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