Structural principle and system design scheme of electronic cigarette

Simply put, e-cigarette is a low-pressure microelectronic atomization device that atomizes a tobacco-scented solution into a mist by heating for use by smokers.

Electronic cigarettes are modern microelectronics technology. The actual electronic cigarette body is a comprehensive structure. The lithium battery is built by a cartridge, a spray chamber, and a smart chip. At the front end of the product is an operating mode indicator that, when you use it, emits light like a real cigarette. The most interesting part of the electronic cigarette is the spray chamber. This is the magic part that happens to be responsible for creating steam like smoke, like a real cigarette. This steam is the result of the heat atomization of the smoke liquid, that is, the smoke oil in the smoke bomb is heated and atomized. At this time, smoke vapor is generated, which is inhaled into the mouth of the user and can satisfy the desire of the smoker.

The structure and principle of electronic cigarette

Electronic cigarettes are also known as "atomized electronic cigarettes", which are essentially different from cigarettes. They do not burn, contain only purified nicotine, contain no tar, and contain no ordinary cigarettes, which cause respiratory and cardiovascular diseases. Chemicals that remove other carcinogens from ordinary cigarettes.

The basic structure of the electronic cigarette is as shown in the figure. It consists of a battery (tobacco rod) + atomizer (smoke) + a cigarette holder. There is a switch on the rod, and there is a light at the bottom to indicate whether there is electricity. The smoke oil passes through the atomizer. Heating produces steam fumes, which themselves have a taste, so there is a variety of aromas. There are generally four flavors of tobacco, fruit, flowers and beverages on the market.

The electronic suction device, which looks like a cigarette, has a red light-emitting diode at the front end. When the user sucks it, the front end of the product emits red light, which is like real lighting, and also generates smoke in the smoke. In the hustle and bustle, the user can enjoy the same artistic concept as a real cigarette.

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

The working principle is that the nicotine solution (reduced by the manufacturer) in the supporting cigarette core (also called the cartridge) is pressurized by the ultra-micro pump and then enters the atomization chamber, and then is atomized by ultrasonic high pressure of 2.2 MHZ to a diameter of 0.5- A droplet of about 1.5 um is absorbed into the lungs. There is a gas flu detector in the built-in wafer, so that the device generates atomization only when it is inhaled through the mouth, and the micro-processed wafer controls the working state of each component.

This product, like cigarettes, inhales nicotine into the lungs so that nicotine can be quickly absorbed in the lungs, and the enjoyable effect after smoking is the same as that of cigarettes. Moreover, the product can be set to different specifications according to the amount of nicotine per inhalation to suit the different needs of each person.

In addition, the solution in the built-in nicotine tank can also be used to formulate the taste of cigarettes of various flavors according to different flavor prescriptions, different nicotine contents, etc., and even according to the special needs of customers, the taste of a certain brand of cigarettes designated by the customer can be customized.

Electronic cigarette system design

The electronic cigarette is composed of the main control chip CSU8RP3125, battery, button, LED breathing lamp and atomizer (see the figure below).

Electronic cigarette detailed design

Short circuit protection

The low-voltage reset function of the chip itself is used to realize the short-circuit protection of the electronic cigarette, and the LVR of the chip is set at 2.4V. When the load terminal is short-circuited, the VDD pin of the chip is instantaneously pulled down to 2.4V, and the chip is reset, NMOS. The control pin of the tube returns to the state of power-on reset, that is, the low level cuts off the NMOS to protect the MOS transistor.

Overcharge protection

Since the battery is directly connected to the VDD of the chip, the internal reference voltage of the chip is used as an input, and VDD is used as a reference. Since the internal reference voltage is fixed, as long as the voltage on VDD changes, the AD value obtained will also be used. There is a corresponding change, the AD value is used to calculate the voltage of the battery terminal. When the chip detects that the battery voltage is higher than 4.2V, let the NMOS control pin output a low level to turn off the NMOS to cut off the charging circuit between the charging terminal and the battery. To prevent overcharging of the battery. The CSU8RP3215 chip uses an internal reference to measure the battery voltage, eliminating the need for an external reference source and saving voltage divider resistors.

Circuit characteristics: 1. Constant voltage charging maximum voltage 4.2V 2. Charging current is 405mA. 3. It is also possible to adjust the charging current and adjust the resistance of the 2nd pin to ground. The formula is: ICH = 1216V / RISET where ICH is the charging current, and the unit is ampere RISET indicating the resistance of the ISET pin to ground. The unit is ohm. For example, if a charging current of 405 mA is required, it can be calculated as follows: RISET = 1216V/0.405A = 3kΩ To ensure good stability and temperature characteristics, RISET recommends using a metal film resistor with a precision of 1%. The charging current can be detected by measuring the voltage at the ISET pin. The charging current can be calculated using the following formula: ICH = (VISET / RISET) &TImes; 1000.