Hi !!
I'm using PGA280 + ADS1259 solution in an analog voltage/current input system. I have multiple input ports, each one with a RC filter at input stage and connected to external multiplexers. External multiplexers are connected to the PGA input ports. Between PGA and ADS1259, I'm using datasheet recommended RC filter. Voltage reference is set to internal and data rate is 14400 SPS.
Using this HW implementation, i have found some crosstalk/intereference between channels. I believe it is related to the settling time of RC filters vs data rate and channels reading. Because of it, I would like to verifiy some doubts about HW and SW implementation.
1. As I'm using external multiplexers (they are not controled by PGA mux control feature at register 0) and at each reading I have to configure PGA gain and input switch control (Register 6), what is the best steps sequence for external multiplexers and PGA configuration ?
Nowadays, I disable external mux, configure PGA gain, configure PGA switches, configure/enable external multiplexer and send start command.
2. About PGA current buffer. According to datasheet: " ... as soon as buffers are turned off, amplifiers settle back to high precision." My question is if I send a start command and buffer are still turned on, my precision will be compromissed ? To avoid it, must I use the start delay ?
To enable buffer feature, I have bit 5 ('T') in command byte. When I have to use it ? Only when doing external mux control or can I use in each PGA write command, as example, set gain, send start command ?
About HW implementation, I can send my schematics. Just give an e-mail.
Regards,
Mateus.