Summary of Reverse Engineering A Counterfeit 7805 Voltage Regulator
The article explores the internal structure of a 7805 voltage regulator, revealing its transistors, resistors, diodes, and capacitors. It explains that this linear regulator converts unregulated input to a stable 5V output by dissipating excess voltage as heat, resulting in low efficiency compared to switching power supplies. The author notes the component is likely counterfeit after microscopic analysis.
Parts used in the 7805 Voltage Regulator:
- Transistors
- Resistors
- Diodes
- Capacitors
- Large control transistor
Under a microscope, a silicon chip is a mysterious world with puzzling shapes and meandering lines zigzagging around, as in the magnified image of a 7805 voltage regulator below. But if you study the chip closely, you can identify the transistors, resistors, diodes, and capacitors that make it work and even understand how these components function together. This article explains how the 7805 voltage regulator works, all the way down to how the transistors on the silicon operate. And while exploring the chip, I discovered that it is probably counterfeit.
A voltage regulator takes an unregulated input voltage and converts it to the exact regulated voltage an electronic circuit requires. Voltage regulators are used in almost every electronic circuit, and the popular 7805 has been used everywhere from computers[1] to satellites, from DVD player and video games to Arduinos[2]. and robots. Even though it was introduced in 1972 and more advanced regulators[3] are now available, the 7805 is still in use, especially with hobbyists.
The 7805 is a common type of regulator known as a linear regulator. (As its name hints, the 7805 produces 5 volts.) A linear regulator is built around a large transistor that controls the amount of power flowing to the output, acting similar to a variable resistor. (This transistor is visible in the right half of the die photo above.) A drawback of a linear regulator is that all the “extra” voltage gets converted into heat. If you put 9 volts into a linear regulator and get 5 volts out, the extra 4 volts gets turned into heat in the regulator, so the regulator is only about 56% efficient. (The main competitor to a linear regulator is a switching power supply – a much more efficient, but much more complicated way to produce regulated voltage. Switching power supplies have replaced linear regulators in many applications, such as phone chargers and computer power supplies.)
For more detail: Reverse Engineering A Counterfeit 7805 Voltage Regulator
- What does a voltage regulator do?
A voltage regulator takes an unregulated input voltage and converts it to the exact regulated voltage an electronic circuit requires. - How much voltage does the 7805 produce?
The 7805 produces 5 volts. - How does a linear regulator control power flow?
A linear regulator is built around a large transistor that acts similar to a variable resistor to control the amount of power flowing to the output. - Why are linear regulators considered inefficient?
All extra voltage gets converted into heat; for example, putting 9 volts in and getting 5 volts out results in only about 56% efficiency. - What is the main competitor to a linear regulator?
The main competitor is a switching power supply, which is more efficient but more complicated. - Can you identify components inside a silicon chip under a microscope?
Yes, you can identify transistors, resistors, diodes, and capacitors that make the chip work. - Is the 7805 still in use today?
Yes, despite being introduced in 1972, the 7805 is still in use, especially with hobbyists. - What did the author discover while exploring the chip?
The author discovered that the chip is probably counterfeit.
