Voltage stabilizer chip 7805 voltage stabilizer chip LM2596 voltage stabilizer chip The voltage stabilizer chip is one of the commonly used electronic devices, of which the 7805 voltage stabilizer chip is the most commonly used. At present, the 7805 voltage regulator chip has three categories L7805, cw7805 and LM7805, so what is the difference between these three voltage regulator chips? This problem will be solved in this article. In addition, this article will also introduce the basic characteristics and applications of the LM2596 voltage regulator chip, let's take a look.

L7805_ There is not much difference between CW7805 and LM7805. It's just that the L, CW and LM in front are just the code names of the manufacturers. The 7805 behind is the code name of the three-terminal regulator (7 series positive regulator, 05 output voltage: DC 5V, current 1A). It can be used in common with regulated 5V DC power supply.

1. Overview of LM7805

Three-terminal voltage regulator integrated circuit LM7805. In electronic products, common three-terminal voltage regulator integrated circuits include LM78×× series with positive voltage output and LM79×× series with negative voltage output. As the name implies, a three-terminal IC refers to an integrated circuit used for voltage regulation. There are only three pin outputs, namely the input terminal, the ground terminal and the output terminal. It looks like an ordinary triode, the standard package of TO- 220 , and the TO-92 package like LM9013.

2. LM7805 pin diagram

7805 is a commonly used three-terminal voltage regulator. As the name implies, the output voltage of 05 is 5v, and it can be fine-tuned. The output ripple of 7805 is very small.

(1) The integrated three-terminal voltage stabilizer is divided into 78××× and 79××× series according to the positive and negative polarity of the stable voltage. The attached figure shows a typical circuit for positive and negative voltage regulation.

(2) Model specifications and pin assignments of the three-terminal regulator.

For example: 78M05 three-terminal voltage regulator can output a stable voltage of +5 V, 0.5 A; 7912 three-terminal voltage regulator can output a stable voltage of 12V , 1A. (3) The shape and pin distribution are shown in Figure 1-25.

3. Main parameters of L7805

L7805, using TO-220 package.

Voltage drop: 2V

Number of outputs: 1

Number of pins: 3

Package Type: TO-220

Operating temperature range: 0°C to +150°C

Part number: 7805

Part Marking: L7805CV

Tolerance, working voltage+: 4%

Voltage Rectifier Type: Positive Fixed

Maximum power supply voltage: 20V

Minimum supply voltage: 8V

Chip number: 7805

Surface Mount Devices: Through Hole Mounting

Maximum input voltage: 35V

Minimum input voltage: 7V

Maximum output voltage: 5V

Maximum output current: 1.5A

Voltage: 5V

Output voltage: 5V

Four, 7805 typical application circuit

7805 Typical Application Circuit Diagram The typical application circuit of the 78XX series integrated voltage regulator is shown in the figure below, which is a regulated power supply circuit that outputs a positive 5V DC voltage. The IC adopts an integrated voltage regulator 7805, C1 and C2 are the input and output filter capacitors respectively, and RL is the load resistance. When the output current is large, the 7805 should be equipped with a heat sink.

The figure below shows the application circuit for increasing the output voltage. Zener diode VD1 is connected in series between pin 2 of the 78XX regulator and the ground, which can increase the output voltage Uo to a certain extent. The output voltage Uo is the sum of the output voltage of the 78XX regulator and the voltage regulator value of the Zener diode VC1. VD2 is the output protection diode. Once the output voltage is lower than the regulated value of VD1, VD2 is turned on, bypassing the output current to protect the output stage of the 7800 regulator from being damaged by the 7805 typical application circuit diagram.

Five, the basic characteristics and application of LM2596 integrated voltage regulator chip

The LM2596 series is a 3A current output step-down switching integrated voltage regulator chip, which contains a fixed frequency oscillator (150KHZ) and a reference voltage regulator (1.23v), and has a complete protection circuit, current limit, thermal shutdown circuit, etc. . Using this device, a high-efficiency voltage regulator circuit can be formed with very few peripheral devices.

LM2596 contains 150KHZ oscillator, 1.23v reference voltage regulator circuit, thermal shutdown circuit, current limit circuit, amplifier, comparator and internal voltage regulator circuit.

The device integrates frequency compensation and a fixed frequency generator, and the switching frequency is 150KHz. Compared with the low-frequency switching regulator, it can use smaller filter components. Since the device only needs 4 external components, a common standard inductor can be used, which optimizes the use of the LM2596 and greatly simplifies the design of the switching power supply circuit.

Its package forms include standard 5-pin TO-220 package (DIP) and 5-pin TO-263 surface mount package (SMD).

The device also has some other features: under certain input voltage and output load conditions, the output voltage error can be guaranteed within ±4%, and the oscillation frequency error is within ±15%; only 80μA can be used Standby current to achieve external power-off; with self-protection circuit (a two-stage down-frequency current-limiting protection and an over-temperature complete protection circuit for power-off in abnormal conditions)

Features are as follows:

1. Output voltage: 3.3V, 5V, 12V and (ADJ), etc., the maximum output voltage is 37V

2. Working mode: low power consumption/normal mode. Can be controlled externally

3. Working mode control: TTL level compatible

4. External components required: only four (not adjustable); six (adjustable)

5. Device protection: thermal shutdown and current limit

6. Package form: 5 feet (TO-220(T);TO-263(S))

Application areas:

1. High efficiency buck regulator

2. Monolithic switching voltage regulator

3. Positive and negative voltage converter