As a new type of energy-saving and environmentally friendly green light source products, LED has broad market prospects. At present, there are thousands of LED driver ICs in the market. Among them, we have encountered a lot of single-chip line structure (Figure 1a).
According to the IC's data sheet, this type of IC is a high-efficiency LED drive control circuit that operates in PWM mode. With an external circuit, it can accommodate a wide input voltage range from 8V to 450V. The external power MOS transistor can be set by a fixed resistor (or capacitor) to reliably drive the LED string in a constant current manner. The LED current can be set by selecting the appropriate current limiting resistor. It also provides a linear dimming function that supports digital pulse (PWM) dimming with a low frequency variable duty cycle.
According to the application and according to different standards, the driving scheme can be divided into three types.
According to the PWM adjustment method, it can be divided into two types: constant frequency and constant off time (Fig. 1).
The voltage applied across the inductor in the steady state multiplied by the on-time is equal to the turn-off time inductor voltage multiplied by the turn-off time: Von*Ton=Voff*Toff, ie (Vin-Vo)*Ton=Vo*Toff.
From the calculation formula of the inductance, the difference between the two can be seen. The inductance calculation in Fig. 1a is L = (Vin–Vo) * Ton / ΔI, and the inductance calculation in Fig. 1b is L=Vo*Toff. /ΔI. Io = Ip - ΔI /2. As shown in the current waveform diagram shown in Figure 2, after the inductance is determined, the input voltage Vin changes in Figure 2a causes the ripple current ΔI to change, so that the output current changes; the ripple current ΔI in Figure 2b is independent of the input supply voltage. Therefore, in a wide voltage application environment where voltage fluctuations are large, a constant off time circuit mode is used.
Some client may feel that 10th Laptop is little old, so prefer 11th Laptop or 12th laptop. However, you will the 10th cpu is even more powerful than 11th, but price is nearly no difference, especially you take in lot, like 1000pcs. As a professional manufacturing store, you can see Laptop i3 10th generation 8gb ram,i5 laptop 10th generation, intel i7 10th gen laptop, etc. It`s a really tough job selecting a right one on the too many choices. Here are some tips, hope help you do that easier. Firstly, ask yourself what jobs you mainly need this Gaming Laptop to do. Secondly, what special features you care more? Like fingerprint, backlight keyboard, webcam rj45, bigger battery, large screen, video graphics, etc. Finally, ask the budget you plan to buy gaming laptop. Thus you will get the idea which laptop is right one for you.
Except integrated laptop, also have graphic laptop with 2gb or 4gb video graphic, so you can feel freely to contact us anytime and share your basic requirements, like size, cpu, ram, rom, video graphics, quantity,etc. More detailed value information provided in 1-2 working days for you.
10th Laptop,Laptop I3 10th Generation 8gb Ram,I5 Laptop 10th Generation,10th Generation Laptop,Intel I7 10th Gen Laptop
Henan Shuyi Electronics Co., Ltd. , https://www.hnsylabtop.com