[introduction] The electronic cigarette is composed of stainless steel shell built-in lithium battery, air flow sensor, control circuit, executive circuit, high-power integrated circuit, high-frequency ultrasonic generator, atomization chamber, smoke liquid core.
      Simply put, e-cigarette is a low-pressure micro-electronic atomization equipment, which atomizes the solution with tobacco flavor into smoke by heating, for smokers to use.
      E-cigarette is a modern microelectronic technology. The actual e-cigarette body is a comprehensive structure. It consists of a smoke bomb, a atomization chamber, and a lithium battery controlled by a smart chip. On the front end of the product is an operating mode indicator that emits light like a real cigarette when you use it. The most interesting part of e-cigarettes is the atomization chamber. That's the part of the magic that happens, is responsible for creating vapor-like smoke, like a real cigarette. This vapor is the result of the heated atomization of the smoke liquid, that is, the heated atomization of the smoke oil in the bomb. At this time, a smoke-like steam is produced, which is inhaled in the user's mouth and can satisfy the smoker's craving.

Structure and principle of electronic cigarette
  Electronic cigarettes, also known as "vaping electronic cigarettes", are fundamentally different from cigarettes in that they do not burn, contain only purified nicotine, do not contain tar, do not contain chemicals that cause respiratory and cardiovascular diseases contained in ordinary cigarettes, and remove other carcinogens in ordinary cigarettes.
      The basic structure of the e-cigarette is as shown in the figure, consisting of a battery (smoke rod) + atomizer (smoke bomb) + cigarette holder. There is a switch on the cigarette rod, and a light at the bottom will show whether there is electricity. The smoke oil will generate steam smoke after heating by the atomizer, and the smoke oil itself is flavored, so there will be various aromas. There are generally four flavors on the market: tobacco, fruit, flowers and beverages.

  This kind of electronic suction device looks like a cigarette, its front end is equipped with a red light-emitting diode, when the user sucks, the front end of the product will emit red light, as if the real ignition, but also produce smoke, in the smoke, the user can enjoy the same mood as the real cigarette.
      It is composed of stainless steel shell built-in lithium battery, air flow sensor, control circuit, executive circuit, high power integrated circuit, high frequency ultrasonic generator, atomization chamber, smoke liquid core.
     The working principle is that the nicotine solution (extracted by the manufacturer) in the supporting smoke core (also known as smoke bomb) is pressurized by the ultra-micro pump into the atomization chamber, and then atomized by the ultrasonic high pressure at the frequency of 2.2 MHZ into about 0.5-1.5 um in diameter of the fog droplets, which are inhaled into the lung. The internal chip has an air fluometer, so that the device only produces atomization when inhaling through the mouth, and the working state of each component is controlled by the micro-processing chip.
     Like cigarettes, the product inhales nicotine into the lungs through smoking, so that nicotine can be quickly absorbed in the lungs, and the addictive effect after smoking is no different from that of cigarettes. And the product can be set to different specifications according to the amount of nicotine inhaled each time to meet the different needs of each person.
     In addition, the solution in the built-in nicotine tank can also be modulated according to different flavor prescriptions, different nicotine content, etc., to prepare a variety of cigarette flavors, and even according to the special needs of customers to customize the taste of a certain brand of cigarettes specified by customers.

Electronic cigarette system design
  The e-cigarette is composed of the main control chip CSU8RP3125, the battery, the button, the LED breathing light, and the atomizer (see the figure below).

Detailed design of electronic cigarette
Short circuit protection
  The low voltage reset function of the chip itself is used to achieve short circuit protection of the e-cigarette, and the LVR of the chip is set at 2.4V. When the load side is short circuit, the VDD foot of the chip is instantly pulled down to below 2.4V, and the chip is reset and NMOS. The control pin of the tube returns to the state of power-on reset, that is, the NMOS is cut off at a low level to protect the MOS tube.

Overcharge protection
  Since the battery is directly connected to the VDD of the chip, the internal reference voltage of the chip is taken as the input and VDD is used as a reference. Because the internal reference voltage is fixed, as long as the voltage on the VDD changes, the AD value collected will also change accordingly. The AD value is used to calculate the voltage at the battery end. Let the control pin of the NMOS output a low level to turn off the NMOS to cut off the charging loop between the charging terminal and the battery to prevent the battery from overcharging. The CSU8RP3215 chip uses an internal reference to measure the battery voltage, eliminating the need for an external reference source as well as a divider resistor.

 Circuit characteristics: 1, constant voltage charging maximum voltage 4.2V, charging current is 405mA. 3, you can also adjust the charging current, adjust the resistance of the second pin to the ground, the calculation formula is: ICH = 1216V/RISET Where ICH indicates the charging current in amperes RISET indicates the resistance of the ISET pin to the ground in ohms. For example, if a charging current of 405mA is required, it can be calculated according to the following formula: RISET = 1216V/0.405A = 3kΩ In order to ensure good stability and temperature characteristics, RISET recommends the use of metal film resistors with an accuracy of 1%. The charging current can be detected by measuring the voltage of the ISET pin. The charging current can be calculated using the following formula: ICH = (VISET/RISET) x 1000.