The ADC128S102EVM has provisions to drive all eight analog input channels, the external power supply, and the connection to the precision host interface (PHI) motherboard to communicate with the user-friendly GUI. These section are outlined in red in Figure 1-1. The final section is the EEPROM section below the J25 PHI connector. The switch, S1, must be in the WR_DIS position and must not be changed.
Table 1-1 lists the related documents that are associated with the ADC128S102EVM.
The EVM board has two subminiature version A (SMA) connectors, with six other footprints to populate the remaining SMA connectors (if required) to connect to the eight analog input channels. Shunt headers are also available in parallel with each respective SMA connector. As shown in Figure 1-2, each shunt header is connected to an analog input channel of the ADC128S102 through an operational amplifier (op amp) driver circuit. An input circuit is connected to each ADC analog input. The driver circuit consists of an initial RC circuit for noise filtering, followed by an OPA2320 (a dual-channel op amp configured, by default, as a buffer). The board has provisions to change the buffer circuit configuration, by removing the 0-Ω resistor and adding the desired RC combination. At the output of each op amp, is a 3-pin header that provides the option to bypass the buffer.
All power supplies required by the EVM are provided by the PHI motherboard. The ADC128S102 requires an analog power supply (VA) and a digital power supply (VD). The analog power supply is set at 5.5 V and is regulated down to 5.3 V using the TPS7A4700. From there, the REF6050 is used to set VA to 5 V. The ADC128S102 uses VA as the reference as well, which defines the analog full scale of the ADC. The EVM has a provision for an external VA. To use an external analog power supply, remove R42 at the REF5060 output, which disconnects the VA supplied by the EVM. Using jumper J27, which is unpopulated by default, an external supply can be connected. There are also footprints available for a decoupling capacitor and a protective diode that must be populated if an external supply is used.
The digital supply VD is set to 3.3 V and is supplied directly from the PHI motherboard.
The EVM is packaged with a PHI motherboard, which provides the required circuitry to connect the EVM to the graphical user interface (GUI). Connect the PHI board to the EVM using J25.
The ADC128S102EVM is out of the box ready to use, and requires minimum set up.