SNAS659B June 2015 – September 2018 TPL5111
PRODUCTION DATA.
When the primary constraint is battery life, the selection of a low power voltage regulator or DC-DC converter to power the µC is mandatory. The first step in the design is to calculate the power consumption of each device in the different modes of operation. An example is the HDC1000 digital humidity and temperature sensor combined with an RF micro. In measurement mode, the RF micro is in normal operating and transmission mode. The LDO or DC-DC converter should be selected to provide the necessary current source. For example, the HDC1000 consumes a maximum of 220 µA during a humidity measurement, and 300 µA during start-up. The CC2531 consumes 29 mA in TX mode. The LDO should be capable of sourcing > 30 mA, which is an easy requirement to meet.
Assuming the desired wake-up interval is 30 seconds, then referring to Table 3, the values for parallel REXT resistors are 32.4 kΩ and 34.8 kΩ.