{"id":1536,"date":"2017-08-28T08:00:37","date_gmt":"2017-08-28T15:00:37","guid":{"rendered":"http:\/\/www.autodesk.com\/products\/eagle\/blog\/?p=1536"},"modified":"2023-09-25T11:39:23","modified_gmt":"2023-09-25T18:39:23","slug":"what-is-a-voltage-regulator","status":"publish","type":"post","link":"https:\/\/www.autodesk.com\/products\/fusion-360\/blog\/what-is-a-voltage-regulator\/","title":{"rendered":"What is a Voltage Regulator?"},"content":{"rendered":"

Regulators, Mount Up:
The Voltage Regulator, and How It Protects Your Circuit<\/h2>\n\n\n

Whether it\u2019s your car, laptop, or smartphone, every electronic device needs some protection from fluctuating voltages. These days, with devices getting packed tighter than ever with sensitive components like microprocessors and integrated circuits (ICs), even the slightest change in voltage can wreak havoc on your carefully designed circuit. So what can a sensitive component do when it requires protection? It needs a regulator to keep voltages running stable and smooth from input to output.<\/span><\/p>\n\n\n

Voltage Regulators at a Glance<\/h2>\n\n\n

In the world of electronic components, the voltage regulator is one of the most widely used, but what does this IC do? It provides a circuit with a predictable and fixed output voltage at all times, regardless of the input voltage. <\/span><\/p>\n\n\n\n

\"lm7805-linear-regulator\"\/
The LM7805 is one of the most popular linear voltage regulators around. (Image source<\/a>)<\/em><\/figcaption><\/figure>\n\n\n\n

How a voltage regulator achieves this task is ultimately up to the designer. Some voltage can be controlled by a simpler Zener diode, while other applications require an advanced topology of linear or switching regulators. At the end of the day though, every voltage regulator has a primary and secondary goal:<\/span><\/p>\n\n\n\n

Primary:<\/b> To generate a steady output voltage of a circuit in response to variations in an input voltage conditions. You might have 9V in, but if you only want 5V out, then you\u2019ll need to step it down (Buck) with a voltage regulator.<\/span><\/p>\n\n\n\n

Secondary<\/b>: Voltage regulators also work to shield and protect your electronic circuitry from any potential damage. The last thing you want is to fry your microcontroller because it couldn\u2019t handle a spike in voltage.<\/span><\/p>\n\n\n\n

When it comes to adding a voltage regulator to your circuit, you\u2019ll typically work with one of two types – Linear Voltage Regulators or Switching Voltage Regulators. Let\u2019s see how both of these work.<\/span><\/p>\n\n\n

Linear Voltage Regulators<\/h2>\n\n\n

This type of regulator acts as a voltage divider on your circuit and is the kind of regulator commonly used when you\u2019re designing low power and low-cost applications. With the linear regulator, you\u2019ll be taking advantage of a power transistor (BJT or MOSFET) that plays the role of a variable resistor, raising and lowering the output voltage of your circuit as your input supply changes.<\/span><\/p>\n\n\n\n

Regardless of what kind of load is placed on your circuit, a linear voltage regulator will always keep pace to provide you with a constant, steady output voltage. For example, a 3-pin linear voltage regulator like the LM7805 provides a consistent, 5 volt 1 amp output so long as the input voltage doesn\u2019t exceed 36 volts.<\/span><\/p>\n\n\n\n

\"lm705-linear-regulator\"\/
The LM705 wired in series to provide a stable output voltage. (Image source<\/a>)<\/em><\/figcaption><\/figure>\n\n\n\n

The downside to this type of regulator ultimately comes down to how it functions. Because it behaves like a resistor to stabilize voltage, it ends up wasting a ton of energy as it converts resisted current into heat. This is why linear voltage regulators are ideally suited for applications where power requirements are low, and the difference between input and output voltages is minimal. Let\u2019s compare two different voltage regulation situations to see how a linear regulator stacks up:<\/span><\/p>\n\n\n\n

With a 10 volt input source that gets stepped down to 5 volts with an LM7805, you\u2019ll end up wasting 5 watts and only getting 50% efficiency from your efforts.<\/span><\/p>\n\n\n\n

Take the same LM7805 regulator and give it a 7 volt input stepped down to 5 volts, and you\u2019ll end up only wasting 2 watts and achieving 71% efficiency.<\/span><\/p>\n\n\n\n

As you can see, the lower your initial input power requirements, the more efficient your linear voltage regulator can be. When working with these regulators in your own circuit, you\u2019ll typically encounter two variations, either as a Series or a Shunt. <\/span><\/p>\n\n\n

Series Voltage Regulator<\/h3>\n\n\n

This conventional regulator has a Zener diode controlled transistor in series with the load. Here the regulator uses as a variable element (transistor in this case), ramping resistance up and down depending on a variable input voltage to provide a steady and consistent output voltage.<\/span><\/p>\n\n\n\n

\"simple-series-regulator\"\/
A simple series voltage regulator circuit providing a regulated DC output. (Image source<\/a>)<\/em><\/figcaption><\/figure>\n\n\n

Shunt Voltage Regulator<\/h3>\n\n\n

This application works similar to a series voltage regulator but isn\u2019t wired in series. All excess voltage is still sent to ground through the same process of variable resistance, which again wastes energy. You\u2019ll most commonly see shunt regulators being used in:<\/span><\/p>\n\n\n\n