Electronic Enthusiast Network has compiled some comments from netizens on the selection and advantages of Coolmos for your reference. The use of Coolmos is a trend because ordinary MOS can no longer meet the actual needs of power supply.
Let me tell you a little bit about my opinion.
1. Coolmos selection. Generally, we choose a MOS based on the following parameters: BV Id Rds Vth Qg Pd, etc. But of these parameters, only Qg and Id are communication parameters, and the others are static parameters. Semiconductors deteriorate as temperatures rise. The dynamic parameters are actually getting worse. The current at 25 degrees is 100A. Maybe at 125 degrees, the current is only 50A, so when selecting, the data at high temperature (aging room) should prevail. After selecting the voltage and current, all that remains is to look at the losses of Coolmos. The Rdson exposed on the surface of Coolmos is lower, only 1/3 or 1/4 of the planar tube, so the conduction loss of the MOS must be much lower than that of the planar tube. Another loss of MOS, switching loss is actually more dominant. The most directly reflected value of switching loss in MOS is Trr. This is also the core parameter of Coolmos. Judging from the development of coolmos, C3 C6 CP CFD CFD2 all work hard on Trr (except C6, which is the Cost down of C3). You are a power supply designer, and you know the reasonable use of Trr better than I do. In practical applications of Coolmos, the Rg driver of the MOS front-end generally has much lower resistance requirements. This also reduces losses. For example, the driving resistance of the front section of 20N60C3 MOS can generally be less than 15mohm, but lower is not always better. The higher the switch, the more EMI problems arise. Therefore, the selection of the driving resistor must be comprehensively considered. If EMI is allowed, the driving resistance should be reduced as much as possible.
2.Whether Coolmos needs to take heat dissipation measures. All I can say is that it depends on the power. For example, on a 150W LED power supply, do you think there is no need to add heat dissipation? On a 15W LED power supply, is there any room for adding a heat dissipation device? Coolmos, on the application side, solves the problem. The power supply solution requires electronic devices to be smaller in size, or even remove the heat sink (such as the iPhone charger). However, when it comes to high power, the most important thing about Coolmos is that it can reduce losses, so a heat sink must be added.
3. The current domestic application of Coolmos is still very one-sided, and there is still a long way to go. For example, in a 70W laptop adapter, many still use 20A planar tubes (or 16A), but we know that the effective current in the actual circuit is actually very small. The use of 20A is just to value its low internal resistance and reduce the loss and reduce temperature rise. Now when many engineers come to review this plan, they still can't wrap their heads around it. If Coolmos is used, he thinks that 16A is needed, and the price will definitely be incomparable for the same current. In fact, Coolmos 10A is enough to replace it. The switching loss of Coolmos is much lower than that of planar tubes. In terms of internal resistance, Coolmos's 10A is not much higher than that of 16A planar. At high temperatures, the basic internal resistance is the same. (If you have the opportunity to post experimental data, the internal resistance of a 16A planar tube and a 10A Coolmos is almost the same at 100 degrees - the premise is that it has a load, which reflects the characteristics of low switching loss), so engineers need to know more about Coolmos. In the medium-voltage MOS (100-150V), Infineon, ST, AO, and FC all have ultra-low on-resistance and ultra-low loss MOS, such as Opti3MOS (which is widely used by Emerson and Huawei and will be the leader in the future) , SDMOS, etc.
In a word: MOS is developing, and the loss will be lower and lower. Power supply solutions will only develop with higher efficiency and smaller size.
The purpose of Coolmos is to pursue: lowest switching loss. On Coolmos, it is through the P-pillar, forming a larger PN junction, thereby reducing Rds. But as you said, Coolmos reduces Rds, so its EAS capability is lower than that of planar tubes, which also places higher requirements on power supply designers. But we all know that if you can afford a Coolmos power supply, it is basically called a high-end power supply, and the design of the solution must be refined. It's not that the Poussin has a stereo worth tens of thousands of dollars, but that the BMW has all original configurations. This is the gap.
