Onboard Voltage Regulation

The health of the power supplied to your system is important as it will affect how your system performs and whether interference or "noise" is present in the system. The type of power system or methodology used has an impact on the quality of the power that is delivered.

Noise or EMI (Electromagnetic Interference) can be present and induced into the system from a number of sources. EMI can cause undesired noise, or errors in the embedded system, which can lead to malfunction, data loss, or damage.

If your application is critical, you would need to ensure that the system is protected from it.

Powering the system from a USB Port is usually practical during development or if the embedded board is connected directly to the PC for data capturing or system monitoring.

Once the application is untethered from the development environment, this usually requires that the system is connected to a durable, long-term power supply.

Powering a system from a USB connection is not ideal as it's a composite connection with both data and power in the same connection. The USB bus can only provide up to 500mA and therefore not suitable for high-power systems.

A voltage regulator is a circuit that creates and maintains a fixed output voltage, irrespective of changes to the input voltage or load conditions. Voltage regulators (VRs) keep the voltages from a power supply within a range that is compatible with the other electrical components.

The voltage regulator, which is usually on the PC board, delivers and maintains a fixed output voltage (VCC) and maintains notwithstanding any changes to the input voltage or load conditions, this ensures that the embedded application runs without interruption.

Nowadays, the "circuit" is a single component that is referenced by a part number, and with the addition of a few components, which may be limited to an input and output capacitor a regulated voltage can be delivered to the circuit.

While the voltage output should not change, there are minimum requirements for the voltage regulator to work. A minimum input voltage is required for the voltage regulator to produce the rated output voltage.

Once you have reached the required input voltage, which should be a short voltage rise time, the rated output voltage will be available. The input voltage should be kept at a reasonable level and if too high, the regulation produces heat. This may increase the heat dissipation in the circuit.

LDOs are useful components as they require a lower input voltage to supply the required output voltage.

The dropout voltage is the minimum voltage required across the regulator to maintain regulation. A 3.3 V regulator that has 1 V of dropout requires the input voltage to be at least 4.3 V. The input voltage minus the voltage drop across the pass element equals the output voltage

Voltage regulation on board is an important aspect of PCB-embedded design. Consistent and stable voltage supply levels are imperative for an application to perform.