Structure principle and system design scheme of electronic cigarette

In short, e-cigarette is a kind of low-pressure microelectronic atomization equipment, which can atomize the solution with tobacco flavor into smoke by heating, for smokers to use.

Electronic cigarette is a modern microelectronic technology. The actual e-cigarette body is a comprehensive structure. It consists of a smoke bomb, an atomization chamber and a lithium battery controlled by an intelligent chip. At the front end of the product is an operation mode indicator that, when you use it, emits light like a real cigarette. The most interesting part of e-cigarettes is the atomization chamber. That's part of the magic that happens, is responsible for creating steam like smoke, like a real cigarette. This steam is the result of heating and atomizing the smoke liquid, that is, heating and atomizing the smoke oil in the smoke bomb. At this time, smoke like steam is produced, which can satisfy the desire of smokers when inhaled into the user's mouth.

Structure and principle of electronic cigarette

E-cigarette is also known as "atomized e-cigarette", which is essentially different from cigarette. It does not burn, only contains purified nicotine, does not contain tar, does not contain the chemical substances that cause respiratory and cardiovascular diseases contained in ordinary cigarettes, and removes other carcinogens in ordinary cigarettes.

The basic structure of the electronic cigarette is shown in the figure, which is composed of battery (cigarette rod) + atomizer (cigarette cartridge) + cigarette holder. There is a switch on the cigarette rod, and there will be a light at the bottom to show whether there is electricity. The smoke oil is heated by the atomizer to produce steam smoke, and the smoke oil itself has a taste, so there will be all kinds of fragrance. Generally, there are tobacco, fruit, flowers and plants, and drinks on the market.

Structure principle and system design scheme of electronic cigarette

Structure principle and system design scheme of electronic cigarette

This kind of electronic smoking device looks like a cigarette, and its front end is equipped with red light emitting diodes. When users smoke, the front end of the product will emit red light, just like real lighting, and also produce smoke. In the smoke, users can enjoy the same artistic conception as real cigarettes.

It is composed of stainless steel shell with built-in lithium battery, air flow sensor, control circuit, executive circuit, high-power integrated circuit, high-frequency ultrasonic generator, atomization chamber and liquid smoke core.

Its working principle is to put the nicotine solution (refined by the manufacturer) in the matched cigarette core (also known as cigarette cartridge) into the atomization chamber after being pressurized by the ultramicro pump, and then atomized into droplets with a diameter of about 0.5-1.5 um by ultrasonic high pressure with a frequency of 2.2 MHz, and inhaled into the lung for absorption. There is an air flow detector in the built-in chip, so that the atomization can be produced only when the instrument inhales through the mouth, and the working state of each component is controlled by the microprocessor chip.

The product, like cigarettes, inhales nicotine into the lung by smoking, so that nicotine can be quickly absorbed in the lung. The effect of smoking is the same as that of cigarettes. Moreover, the product can set different specifications according to the amount of nicotine inhaled each time, so as to meet the different needs of each person.

In addition, the solution in the built-in nicotine tank can also modulate the taste of cigarettes with different tastes according to different flavor prescriptions and different nicotine contents, and even customize the taste of a certain brand of cigarettes specified by customers according to the special needs of customers.

Design of electronic cigarette system

The electronic cigarette is composed of the main control chip csu8rp3125, battery, button, led breathing lamp and atomizer (see the figure below).

Structure principle and system design scheme of electronic cigarette

Detailed design of electronic cigarette

Short circuit protection

The low voltage reset function of the chip is used to realize the short circuit protection of the electronic cigarette. The LVR of the chip is set at 2.4V. When the load side is short circuited, the VDD pin of the chip is pulled down to below 2.4V instantaneously, and the chip is reset, NMOS. When the control pin of the MOSFET returns to the power on reset state, the NMOS is cut off at low level to protect the MOSFET.

Overcharge protection

Because the battery is directly connected to the VDD of the chip, the internal reference voltage of the chip is used as the input and the VDD is used as the reference. Because the internal reference voltage is fixed, so as long as When the voltage on VDD changes, the collected ad value will also change accordingly. When the chip detects that the battery voltage is higher than 4.2V, the control pin of NMOS outputs a low level to turn off the NMOS to cut off the charging circuit between the charging end and the battery to prevent the battery from overcharging. Csu8rp3215 uses an internal reference to measure the battery voltage, which not only saves the external reference source, but also saves the divider resistance.

Structure principle and system design scheme of electronic cigarette

Circuit characteristics: 1. The maximum voltage of constant voltage charging is 4.2V 2. The charging current is 405ma. 3. The charging current can also be adjusted to adjust the resistance from the second pin to the ground. The calculation formula is: ICH = 1216v / RISET, where ICH represents the charging current in amperes and RISET represents the resistance from the Iset pin to the ground in ohm. For example, if 405ma charging current is required, it can be calculated according to the following formula: RISET = 1216v / 0.405a = 3K Ω In order to ensure good stability and temperature characteristics, RISET recommends using metal film resistor with accuracy of 1%. The charging current can be detected by measuring the voltage of Iset pin. The charging current can be calculated by the following formula: ICH = (viset / RISET) & times; 1000.