Product overview
PM2.5 laser dust sensor module LD12 is a high-precision particle sensor based on the theory of laser MIE scattering. It can continuously collect and calculate the number of suspended particles with different particle sizes in air per unit volume, that is the concentration distribution of particles, and then convert to mass concentration. And output in the form of universal digital interface.
The sensor can be embedded with various instruments related to the concentration of suspended particulates in the air or environmental improvement equipments to provide timely and accurate concentration data.

Working principle
laser sensor LD12 adopts MIE spherical particle scattering principle, that is, laser sensor uses laser to irradiate suspended particulate matter in the air to produce light scattering, photoelectric detector collects scattering light intensity in a certain angle range, the scattering light intensity will be linearly converted to voltage, and then sent to data processing system, the data processing system take the principle of Michaelis scattering theory to deal with the datas, then the equivalent particle size and the number of particles with different particle sizes per unit volume are obtained.

Main feature
1  High measure accuracy up to 0.1μm
2  Zero error alarm rate
3  Real-time response and support for continuous data collecting
4  Minimum resolution particle size 0.1μm
5  Electronic controlled devices lifetime > 8 years, average working time > 5 years.
6  Wide range of application, no need for air duct design, compatible with multi-protocol output
7  light and thin design, suitable for detectors, wearerable equipments, air purifiers, fresh air systems, etc.
8  Six-sided shielding combined the software anti-jamming algorithm, with higher anti-jamming performance
Output result
The main output is the mass and number of particles of various concentration in unit volume, in which the unit volume of the number of particles is 0.1L, and the mass concentration is μg/m³. The output has 2 states : active output and passive output, the default state of sensor is active output when it power on, that is, the sensor sends serial data to host computer at a interval of 1 second.
Tips for circuits designing  
1, LD12 sensor working current is 5V , data commnuicate and control pins need 3.3V as the high level ,mainboard MCU is 5V power supply , need to add level convert ships or circuits between the communication cables (RXD ,TXD ) and controls cables ( Set , RESET)
2, SET and RESET inside has pull-up resistor , it should be suspended when not use
3, Pin7 is to use for procedure internal debugging, it should be suspended when at the application circuits .
4, Be attention when it is in dormant states , the fans should stop working, it need at least 30s stable time to restart to get accurate datas , sensor workimg times should not less than 30s when the dormant state is waked up.
Tips for product installation
1, Metal case and internal power should be in conduction ,do not connect it with other external plate resistance circuits or chassis shells .
2, The best installation way is when the plane of air inlet and air outlet is close to the air hole of the user's inner wall and external connection,if it can'be t realized ,there will be no occlusion within 2 cm of the air outlet . it should has a structure between the plane of air inlet and air outlet to isolate the airflow,so that to avoid direct backflow of air from the air outlet to the air inlet inside the user,
3, The size of air hole for air inlet plane in the user inner wall should not smaller than that of air inlet plane .
4, When used for some products such as purifier,do not directly put the sensor into the purifer itself air duct ,otherwise it should separately set up a structure space to put the sensor inside of it , so that isolate itself air duct with the purifer's air duct.
5, When it used for purifier or fixed detection equipments , the position of purifier should be higher 500px above the ground,otherwise it may be polluted by lager dust particle and even the floccules near the ground ,cause the fans twine and resist to return.
6, Sensor is a whole element,the user do not disassemble it ,including the metal shield ,in case bring irreversible damages.