JAJSEC1C November 2019 – July 2020 ADS8686S
PRODUCTION DATA
For applications that require a reference voltage with a lower temperature drift or a common reference voltage for multiple devices, the ADS8686S offers a provision to use an external reference by using the internal buffer to drive the ADC reference. To select external reference mode, either tie the REFSEL pin low or connect this pin to DGND. In this mode, an external 2.5-V reference must be applied at REFIO (pin 33), which becomes a high-impedance input pin. Any low-drift, small-size external reference can be used in this mode because the internal buffer is optimally designed to handle the dynamic loading on the ADC reference input. The output of the external reference must be filtered to minimize the resulting effect of the reference noise on system performance. Figure 7-7 depicts a typical connection diagram for this mode.