ADSP-BF536 - RTC Power Consumption - solution for UL certified application...
In order to get a UL certification, we designed in a 1K series resistor to the RTCVDD pin. This value resulted from the requirement, that according to UL, a battery must not be loaded with currents higher than 1/3 of its rated current( 30mA in our case.). At 3.3V nominal battery voltage, this results in a series resistor being required of min. 330 Ohms We decided to use 1k Ohm. Unfortunately, with the resistor in line. the RTC dooes not work correctly anymore. It appears as if the RTCVDD is breaking dowm momentarily.
Question: Would a 1nF capacitor to ground, connected to the RTCVDD pin be allowed?
There is nothing specified in the datasheet for this.
Testing with the 1nF capacitor showed, that it seems to work. So is there anything that would contradict the use of this 1nF capacitot, besides the leakage current?