Other Parts Discussed in Thread: MSP430F4270, , TS5A4624, TPS22860
I am trying to do an external MPPT in the bq25570 EVM using the DAC module of MSP430F4270 microcontroller. To switch between the MPP reference source I am using the TS5A4624 switch in the configuration as shown in the figure.
The idea is to not do the MCU-assisted MPPT until the VBAT (CBAT > 30uF) bus has been charged to say 3V. However, since we know that the 16-second-periodic-sampling cannot be disabled in bq25570, I see bad interference on my VREF signal. It is randomly over-riding the DAC-generated VREF and going to 80% MPPT. I am guessing this could be because the NC pin in my TS5A4624 switch is floating.
Any suggestion on what to connect NC pin? or, do you see any other obvious issue here? Thanks!