Power Supply

The supply circuit for the prototype board is different from the supply circuit planned for the production board. For the prototype board, a battery circuit was used. This circuit is based on an LT3032-5 IC. It is powered with two 9V batteries in series with the ground in the middle.

Figure 12: Prototype Board Supply Circuit

For the production board, a USB powered circuit is planned. It uses a buck converter with a charge pump inverter for the analog supply and a single buck converter for the digital supply.

Figure 13: Production Board Analog Supply Circuit

Figure 14: Production Board Digital Supply Circuit

For both the prototype supply and the planned supply, the applications example available in the product’s datasheets were followed. Additionally, all op amp supply pins are decoupled with two 0.1µF capacitors placed close to these pins. Apart from the supply circuits, one difference between the prototype board and the production board is the ground plane configuration. In the prototype board, since only analog circuitry is on the board, a single ground plane was used, as shown in figure 2. For the production board, a split analog-digital ground plane will need to be used to prevent crosstalk of digital signals into analog signals, as shown in figure 1.