Incorporating HV Microcontrollers Into Design
Designing embedded microcontroller applications can be challenging. The biggest challenge is designing a power supply unit for the microcontroller. It is particularly because the supply voltage is much higher than the maximum VDD (positive supply voltage) of the microcontroller.
Experienced embedded designers know that you can simplify the embedded design in such instances by introducing a shunt regulator. With the aid of this regulator, the microcontroller can operate on a variety of voltages. An additional advantage is, the topology of the shunt regulator allows other circuitry, to get power from the VDD pin, even though it is not part of the microcontroller.
A shunt regulator works by producing a voltage drop through a pass resistor. The VDD pin voltage is monitored and vetted against an internal voltage. Depending on the comparison, the current in the resistor gets adjusted, producing the voltage drop.
This voltage drop must confirm to the difference between the microcontroller VDD and supply voltage. But designing a shunt circuit is not easy. The design should ensure that the range of currents under the control of the regulator, can create the voltage drop.
Awareness of Ohm’s law is critical to designing microcontroller applications with shunt regulators. The problem is, the supply voltage and the load current are not constant. On the other hand, the range of currents under the control of the regulator is also limited. Custom power supplies are a possible solution to these issues.