Application advantages of FP7195 to analog constant current dimming chip in machine vision light source

“Machine vision is a rapidly developing branch of artificial intelligence. Simply put, machine vision is to use machines instead of human eyes to make measurements and judgments. Lighting is an important factor affecting the input of machine vision system, which directly affects the quality and application effect of input data. Increased computing power, iteration of higher-resolution sensors, faster scan rates, and improved software capabilities have driven faster buses, which in turn allow larger Images are transferred and processed faster.

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Machine vision is a rapidly developing branch of artificial intelligence. Simply put, machine vision is to use machines instead of human eyes to make measurements and judgments. Lighting is an important factor affecting the input of machine vision system, which directly affects the quality and application effect of input data. Increased computing power, iteration of higher-resolution sensors, faster scan rates, and improved software capabilities have driven faster buses, which in turn allow larger Images are transferred and processed faster. Therefore, the camera of machine vision tends to be high-resolution, and because different ambient light will interfere with the imaging of the camera, light sources such as back lighting, forward lighting, structured light, and stroboscopic lighting are needed for fill light. The requirement for the light source is to support high-resolution dimming control and stable load regulation (individual devices may experience a drop in power supply voltage during operation due to sudden overloading of the power supply).

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 (the 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, the FP7195 will Let the MOS fully open. When the input voltage drops below the LED voltage, the output current will decrease 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 method

In the PWM dimming state, the LED brightness will have two states of “bright” and “dark”. Different PWM duty can present different brightness. When the frequency of PWM dimming is too low, there will be a stroboscopic (Flicker) problem. If analog dimming is used, the LED will be constantly bright. 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 is not lit in some frames, and the so-called stroboscopic phenomenon (Flicker) will appear on the video screen.

FP7195 supports PWM digital dimming function and analog dimming, which can control the output current from 0.1% to 100%. Pulling the DIM pin voltage below 0.05V for more than 20ms can make the FP7195 enter the sleep mode with low power consumption. As long as the DIM pin voltage is pulled over 0.1V, the FP7195 will wake up again. If you do not use the dimming function, be sure to supply a voltage greater than 2.6V to the DIM pin. Digital dimming FP7195 can support PWM digital dimming, as long as a digital signal with a frequency of 500Hz~200kHz is input to the DIM pin, the duty cycle of the PWM digital signal can be controlled to control the output current 0.1%~100% (reference voltage 0.1 mV~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. The IC finally processes the signal as a DC voltage for regulation. The PWM duty ratio (Duty) and the percentage of output current (ILED(%)) conversion formula is as follows:

Analog dimming FP7195 also supports analog dimming (DC dimming), as long as 0.1~2.5V is input to the DIM pin, the output current can be controlled by 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 driven by all light sources within 80V, and the analog dimming function guarantees all the requirements of the camera for fill light during the operation of the entire system. It is a very suitable chip solution in the field of machine vision light sources.