Other Parts Discussed in Thread: CC2591, REF3318
Hi all,
I am developing a low power device with CC2530 + CC2591. I am using the CC2530 ADC capabilities in order to measure the battery voltage. If I use the 1.15V internal reference or AVDD5 reference the CC2530 current consumption is about 1.2uA. However, if I use an external reference (REF3318 from TI) and I connect it to P0_7 pin (dedicated CC2530 external reference) the CC2530 current consumption rises to 255uA. This is much more than REF3318 current consumption, which it is 3.9uA. The reason to use the 1.8V reference is because I have others analog signals from ICs which Span voltages are 1.7V...
It is important to clarify that P0_7 is used to configure GAIN MODE (low or high) of CC2591, but in my case I have a pullup in HGM so as to use P0_7 as a external reference ADC. In my firmware I have disabled also the code where P0_7 is used to initialize the CC2591 as a gain mode. This current through this pullup is roughly 0.1uA.
The total device current consumption is 75uA, including the current consumption of REF3318 but without connecting its output to P0_7 pin. When I connect it, the total current rises to 330uA (255uA for the CC2530).
I could reduce the total current to 200uA (155uA for the CC2530) configuring the P0_7 as an input 3-state once the ADC conversion is done. BUT I have more than two-fold consumption...
My questions are:
1. It is possible to reduce this consumption when REF3318 output is connected to P0_7 pin?
2. What is the reason for this increase? Maybe is the consumption of the MUX for ADC reference? If yes, why this consumption is not increased when I use the internal 1.15V o AVDD5 references?
Thanks.
