78L05 Voltage Regulator Characteristics, Applications, 78L05 vs 7805 and More
11 January 2024
Ⅱ. What are the characteristics of 78L05?
Ⅲ. Technical parameters of 78L05
Ⅵ. Application circuit of 78L05 voltage regulator
Ⅶ. What is the difference between 78L05 and 7805?
The 78L05 is a three-terminal voltage regulator manufactured by Texas Instruments. In this article, we will introduce it in terms of features, specifications, working principles, usage scenarios, etc., so that you can better apply this chip.
78L05 is a fixed voltage three-terminal integrated voltage regulator that can be used in many applications. Its excellent internal current limiting and thermal shutdown characteristics make it particularly suitable for overload conditions. When used to replace the traditional Zener diode-resistor bank, the output impedance is effectively improved, but the bias current is greatly reduced. In addition, it can be used together with other power transfer devices to form a high-current regulated power supply, such as a voltage regulator that can drive an output current of up to 100 mA. In the 78L05 voltage regulator, the first two numbers like "78" are positive voltage, "05" is the output voltage produced by this IC, like 5V, the letter "L" between "78" and "05" is low current, such as 0.1A.
Alternatives and equivalents:
• AMS7111
• LM317
• LM7805
• LM7805CT
• LM7905
• TL750L05
• LM117V33
• Low power consumption: The 78L05 has a relatively low quiescent current, which is very beneficial for battery-powered applications that require long-term operation.
• Short-circuit protection: 78L05 is an integrated circuit with short-circuit protection function. It can automatically shut down the output when the output is short-circuited to avoid damage to the equipment.
• Stability: It is a digital voltage converter with relatively good stability and can provide a relatively stable output voltage.
• Thermal protection: It usually has overheating protection feature. When the chip temperature exceeds the safe range, it automatically reduces the output current to prevent overheating damage.
The following are some common technical parameters of 78L05:
• The input voltage range of 78L05 is 7V to 35V.
• The output voltage of 78L05 is 5V.
• The 78L05's static voltage adjustment accuracy is ±5 percent.
• The temperature stability of 78L05 is ±2 percent.
• The maximum output current of the 78L05 is 100mA.
• The 78L05 has an operating temperature range of 0°C to 125°C.
• The package forms of 78L05 are TO-92, SOT-89, SOT-223, etc.
The working principle of 78L05 is to reduce the input voltage to a stable output voltage by adjusting the voltage difference between the pins. Specifically, when the input voltage changes, we adjust the voltage difference between the pins so that the output voltage remains constant. In the 78L05, transistors and resistors form an amplifier circuit. We stabilize the output voltage by negative feedback. When the input voltage increases, the current of the transistor increases, causing the voltage drop of the resistor to increase, which reduces the base voltage of the transistor, causing the current of the transistor to decrease, and ultimately keeping the output voltage stable. Conversely, when the input voltage decreases, the current in the transistor decreases, the voltage drop across the resistor decreases, and the base voltage increases, thus increasing the current in the transistor and keeping the output voltage stable.
The 78L05 can function in many different application areas, including but not limited to the following:
• Automotive electronics: In automotive electronic systems, stable power supply is crucial to ensure the normal operation of various electronic components (such as navigators, car audio systems, instrument panel displays, etc.). 78L05 can provide reliable 5V power supply in automotive electronics to meet the needs of various functional modules.
• Electronic instruments: 78L05 can be used in various electronic instruments such as measuring equipment, laboratory equipment and test instruments. It provides a stable 5V power supply to ensure the normal operation of circuit components.
• Communication equipment: Wireless communication equipment, network equipment and telephone systems all require stable power to ensure their normal operation. 78L05 can provide stable 5V power supply in these devices to ensure the reliability of signal transmission and data processing.
• Computer hardware: Computers and their associated hardware often require reliable voltage regulators to provide stable power. The 78L05 can be used to power computer motherboards, graphics cards, hard drives and other peripheral devices.
• Consumer electronics: 78L05 is widely used in various consumer electronics, such as smartphones, tablets, audio equipment and home appliances. These devices often require an efficient and stable power supply, and the 78L05 provides the required power and stability.
The 78L05 voltage regulator application circuit is shown in the figure below. This circuit is used to regulate a 12V input voltage to a 5V output voltage. In this circuit, a 78L05 voltage regulator plays a key role. The 78L05 voltage regulator includes three terminals, namely i/p, o/p and GND. So we connect the GND pin to the system GND by connecting the input pin to vin.
With the help of a voltage regulator IC, the input voltage of 12V is regulated to 5V. Therefore, this output voltage is very useful for activating small loads. Rated current is less than 100mA. The maximum current provided by the 78L05 regulator is 100mA. In the above circuit, capacitors such as C1 and C2 are connected to the input and output terminals. The main function of these capacitors is to filter noise from the input voltage. Of course, using exact capacitor values is not mandatory, but a "C1" value of 10μF and a "C2" value of 1μF would be a good choice. These voltage regulators can limit current and protect once the junction temperature is exceeded. If you connect this circuit to a high current load, it may heat up and eventually stop working. So using a suitable voltage regulator is a perfect choice. In addition to being used as a voltage regulator, it can also be used as a current regulator, short circuit protector, boost circuit, variable voltage regulator.
78L05 and 7805 are commonly used linear voltage regulator chips with similar functions and characteristics. But there are some minor differences between them in terms of parameters and functions.
1. Input voltage and output current
The input voltage range of 78L05 is 30V to 35V, and the output current is 100mA. The input voltage of 7805 is not greater than 35V, and the maximum output current is 1A.
2. Package
78L05 adopts SOT-89 or TO-92 package, while 7805 can use TO-220, TO-39 or TO-3P and other package forms.
3. Function
78L05 is particularly suitable for overload situations. When used to replace the traditional Zener diode-resistor bank, the output impedance is effectively improved, but the bias current is greatly reduced. In single-point voltage stabilization situations, in-card adjustment is required to limit noise and solve distribution problems. In addition, it can be used together with other power transfer devices to form a high-current regulated power supply, such as a voltage regulator that can drive an output current of up to 100 mA. The internal circuit of the 7805 three-terminal voltage regulator IC has overvoltage protection, overcurrent protection, and overheating protection functions, which makes its performance very stable. It is capable of achieving an output current of more than 1A. In addition, it has a good temperature coefficient, so it has a wide range of applications.
Frequently Asked Questions
1. What does a 78L05 do?
The 78L05 is a 5V fixed 3-terminal voltage regulator delivering up to 100mA of output current and equipped with internal limiting + thermal shutdown features for overload immunity. Implementing this device at point- of-source removes the complexity of single point regulation methods with reduced noise.
2. Is 78L05 a transistor?
78L05 is an integrated +5V voltage regulator, not a transistor. These ICs aren't exactly identical, depending on the manufacturer, but their pin-out is.
3. What is the current limit of 78L05?
The maximum current supplied by the 78L05 regulator is 100mA.
4. What is 78L05 voltage regulator?
Description. The 78L05 is a monolithic three-terminal positive regulator with internal current limiting, thermal shutdown, and output transistor safe area protection, making it practically indestructible.
