Machine vision is a rapidly developing branch of artificial intelligence. Simply put, machine vision is the use of machines instead of human eyes for measurement and judgment. Lighting is an important factor affecting the input of the machine vision system, which directly affects the quality and application effect of the input data. Increases in computing power, iterations of higher-resolution sensors, faster scan rates, and improvements in software capabilities have driven faster buses, which in turn allow larger sensors with more data. Images are transferred and processed at a faster rate. Therefore, the camera of machine vision tends to be high-resolution, and because different ambient light will interfere with the imaging of the camera, it is necessary to have light sources such as backlighting, forward lighting, structured light and strobe lighting for supplementary light. The requirement for the light source is to support high-resolution dimming control and stable load regulation (individual equipment may experience a drop in power supply voltage due to sudden overload of the power supply during operation).
1. Basic performance
1. Zero differential pressure
The maximum duty cycle of FP7195 can reach 100%, so the input voltage can be almost equal to the LED voltage during operation (circuit components will have a voltage drop, so the input voltage will not be equal to the ED voltage). When the input voltage is lower than the LED voltage, FP7195 will Make the MOS fully open. When the input voltage drops below the LED voltage, the output しED current will drop accordingly. Once the input voltage is higher than the LED voltage, the normal constant current output can be restored immediately.
2. Load Regulation
2. PWM to analog dimming mode
In the PWM dimming state, the LED brightness will have two states of "bright" and "dark". Different PWM duty can show different brightness. When the frequency of PWM dimming is too low, there will be flicker (Flicker) problem. If analog dimming is used, the LED will be constantly on. During the dimming process, the IC will only change the output current value, and the LED brightness will also change accordingly, and there will be no flicker (Flicker) problem.
As shown in the picture above, the camera does not turn on the lights in some frames, and the so-called flicker phenomenon (Flicker) will appear on the video screen.
FP7195 supports PWM digital dimming function and analog dimming , and can control the output current from 0.1% to 100%. Pulling the voltage of DIM pin below 0.05V for more than 20ms can make FP7195 enter the sleep mode with low power consumption. As long as the voltage of DIM pin is pulled more than 0.1V, FP7195 will wake up again. If you do not use the dimming function, please be sure to give the DIM pin a voltage greater than 2.6V.
digital dimming
FP7195 can support PWM digital dimming. Just input a digital signal with a frequency of 500Hz~200kHz at the DIM pin and control the duty cycle of the PWM digital signal to control the output current from 0.1% to 100% (reference voltage 0.1mV~100mV ). The high-potential voltage of PWM can accept 2.6V~5V. After the high-potential part enters the IC, it will be processed as 2.5V. Finally, the IC will process the signal as a DC voltage for regulation. The PWM duty cycle (Duty) and the output current percentage (ILED(%)) conversion formula is as follows:
analog dimming
FP7195 also supports analog dimming (DC dimming), as long as 0.1~2.5V is input at the DIM pin, the output current can be controlled from 0.1%~100% (reference voltage 0.1mV~100mV). The conversion formula of DIM pin voltage (VDIM) and current percentage (ILED(%)) is as follows:
Summarize
FP7195 can be used to drive all light sources within 80V. The function of converting to analog dimming ensures all the requirements of the camera for supplementary light during the operation of the entire system. It is a very suitable chip solution for the field of machine vision light sources.