SLAS605C June 2008 – July 2018 ADS7950 , ADS7951 , ADS7952 , ADS7953 , ADS7954 , ADS7955 , ADS7956 , ADS7957 , ADS7958 , ADS7959 , ADS7960 , ADS7961
PRODUCTION DATA.
Refer to the PDF data sheet for device specific package drawings
The use of a buffer relaxes the RSOURCE requirements to an extent. Charge from the sample-and-hold capacitor no longer dominates as a residual charge from a previous channel. Although having good performance is possible with a larger impedance using the OPA192, the output capacitance of the MXO also holds the previous channel charge and cannot be isolated, which limits how large the input impedance can finally be for good performance. In this configuration, the 1xVREF range allows slightly higher impedance because the OPA192 (20 V/µs) slews approximately 2.5 V in contrast to the 2xVREF range that requires the OPA192 to slew approximately 5 V.