1 - Printed Circuit Board (PCB)

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In simple terms, printed circuit boards (PCBs) are a common medium of implementing circuits. When considering the implementation of circuit design in any type of industry such as in robotics or consumer electronics, you can be absolutely certain that printed circuit board (PCB) technology is used. PCBs are complex and can vary greatly in construction based on application.

2 - Voltage Regulation

By definition, voltage regulation is the ability or measure of how well a system can provide a stable output voltage over a wide range of input and output load conditions. If a system is able to provide a stable output voltage at a particular load condition, but not at other common ones, its voltage regulation is poor.

Let us consider the simple voltage divider network with an input voltage Vin and output voltage Vout.

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At a glance, it may appear as though we can select resistors R1 and R2 so that we can step-down our input voltage Vin to an appropriate output voltage Vout. What happens if we connect our output terminals (Vout and GND) to a realistic load that has a non-zero load resistance RL?

It can be seen that the input voltage Vin will no longer regulate to the desired output voltage Vout based on the previously selected resistors R1 and R2 due to the impact of the load resistance RL has on the output voltage of the system based on the governing equation above. Since voltage dividers are sensitive to output load conditions, they are not very good voltage regulators!

Example: Let’s say we did not know any better and wanted to design a voltage divider to step-down an input voltage of 5V to an output voltage of 3.3V (assume R1 = 10kΩ).

a) At no-load conditions, what is the required value of R2 to achieve this step-down conversion?

b) With the required value of R2, if a load with load resistance RL of 1kΩ is connected to the output terminals of the voltage divider, what is the resulting output voltage Vout?

3 - Voltage Regulator

Voltage regulators are systems which are used to convert an input voltage to a stable output voltage under a variety of different input and output load conditions. Voltage regulators can be characterized by many parameters, here are a few:

• Efficiency

• Noise

• Output voltage stability

• Cost

• Board density

Voltage regulators can be categorized into two characteristic types:

• Switching regulators (buck converters, boost converters, buck-boost converters, etc.)

• Linear regulators (low-dropout regulators, etc.)

3.1 - Step-Down Voltage Regulator

A step-down voltage regulator is a type of voltage regulator which converts an input voltage to an output voltage where the output voltage is less than the input voltage (hence the term “step-down”). For the purpose of this bootcamp, we will not be implementing switching voltage regulators in order to maintain onboarding simplicity. It should be noted that all linear regulators are step-down regulators.

3.2 - Low-Dropout Regulator (LDO)

In this bootcamp, you will be selecting a low-dropout regulator and implementing it onto your custom PCB. A low-dropout regulator (LDO) is a type of step-down linear regulator that uses resistive elements to step down an input voltage to an appropriate output voltage with reasonable stability. An LDO consists of the following components:

• Pass-transistor (Internal)

• Input and output capacitors (External)

• Feedback resistor network (External)

• Error amplifier network (Internal)

At a high-level, the working principle of an LDO can be defined as follows. An LDO:

• Steps down an input voltage to a respective output voltage for a given amount of load current by dissipating power across the pass-transistor.

• Uses capacitors for decoupling along the input voltage and output voltage rails in order to provide device stability and a stable output voltage for reliable voltage regulation.

• Is able to deliver its target output voltage through the use of a feedback resistor network that samples the output voltage into an error amplifier network. This error amplifier network provides closed-loop feedback to the system by adjusting the control pin of the pass-transistor to ultimately converge on its desired output voltage.

In industry, LDOs are implemented as integrated chips (ICs). The pass-transistor, error amplifier network, and other aspects for fundamental operation are internal to the IC. For device and output voltage stability, the input and output capacitors are implemented externally due to their size. For LDOs with the ability to provide a range of output voltages (adjustable LDOs), the feedback resistor network is externally implemented such that you, the hardware designer, can choose certain resistors to achieve a desired output voltage.

Now that you’ve learned about the building blocks of the design challenge you will be working on, let’s get started in Altium Designer, the ECAD software which you will be using to create your project.