JAJSPR4B April 2023 – September 2023 PGA855
PRODUCTION DATA
The output voltages of the PGA855 are balanced with respect to the voltage on the output common-mode pin, VOCM. The starting point for most designs is to assign an output common-mode voltage for the PGA855. For ac-coupled signal paths, this voltage is often the default mid-supply voltage, so as to retain the most available output swing around the voltage centered at VOCM. For dc-coupled signal paths, set this voltage between a maximum of VLVDD – 1.5 V and minimum of VLVSS + 1.5 V. For precision ADC applications, this voltage is typically the input common-mode voltage of the ADC.
The voltage at the VOCM pin is internally buffered to bias the fully differential output amplifier, eliminating the need for an external VOCM buffer. In the event that the VOCM pin is left floating, the output common-mode voltage is biased at output mid-supply using an internal 500-kΩ / 500-kΩ resistor divider network connected between the output-stage power-supply pins.