[Live Review] ROHM DCDC Converter Design Seminar

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[Live Review] ROHM DCDC Converter Design Seminar [Copy link]

Live broadcast time: July 4 Live broadcast content: Power management systems are key to a variety of electronic devices. This seminar will share ROHM's cutting-edge technology in the field of DC/DC converter design, and discuss the two major topics of "Basic Principles of Switching Regulators" and "Component Design and Practical Evaluation". Live video:

How should I choose the input filter capacitor?

DC-DC converter design, considering the performance of the power supply circuit, what factors should be considered when designing?

Why don't reference design materials connect low-value resistors in series with the bootstrap capacitor?

What issues should ROHM DC/DC pay attention to in hardware design? Is there a design guide?

……

If you want to know the answers to these questions, please click on the live review video below~

Q&A summary of the live broadcast room:

• Basic knowledge

1. What type of capacitor should be selected for the soft start time setting capacitor? Ceramic capacitor with good temperature characteristics 2. Regarding phase compensation, can we just refer to the datasheet directly? The phase compensation calculation is very complicated. Generally, we refer to the spec and then adjust the gain and phase 3. Input capacitor, 10uf and 0.1uf which one should be closer to the chip? 1uF 4. Does light load mean small output current? Why is the switching loss large at this time? Relative to conduction loss, switching loss is large 5. In the selection of output capacitor, the specific capacitance reference circuit recommends 47uf. If I choose 10uf*4 and 47uf*1, what are the similarities and differences? Good for EMI and ripple 6. What are the main performance parameters of DC conversion circuit? Corresponding characteristics, efficiency, ripple, noise, etc. 7. Where is the speic topology generally used? Generally used in occasions where the input voltage changes, such as automotive products 8. If the power supply is easily disturbed by external motor startup, what are the good solutions? The motor load changes greatly, requiring the power supply to have good response characteristics and respond quickly to load changes 9. Among these topologies, are the buck types mainly explained? Other factors that may be involved Buck is the most basic. If you understand this, other topologies will be easy to understand 10. What factors should be considered when selecting power inductors for DC/DC design? Inductance, rated current, esr, temperature rise characteristics, etc. 11. How to determine the frequency of PWM switching? Power, efficiency, noise, peripheral devices, etc. 12. When setting the output voltage, is the accuracy of selecting resistors the higher the better? It depends on your load requirements 13. Can ceramic non-polar capacitors be used to replace polar capacitors for filter capacitors? In what cases can they not be replaced? They can be replaced 14. What does the output ripple of DC/DC design depend on and how should it be adjusted? Frequency, inductance, capacitance value, etc. 15. In terms of chip selection, is it mainly based on similar circuit designs already available on the website? What other considerations are there System requirements for your product design 16. What are the characteristics of feedback loop control? Voltage, current feedback, OFF time mode, etc. 17. Whether it is PCB design or measurement value, is it true that the shorter the connection line, the better? In the absence of interference, the shorter the better 18. Will all protection circuits automatically restart after protection? There are two types: latch and auto reset 19. Does the efficiency of DC/DC have anything to do with the switching frequency? It has a lot to do with it 20. How to do output short circuit protection in the boost solution? OCP and SCP can both be detected 21. So PWM and PFM are not good, so which mode is more perfect PEM mode is generally used in portable products, requiring high efficiency under light load 22. The input capacitor has a DC effect, and the actual capacitance value will be much lower. So when we actually choose this capacitor, do we need to make corresponding compensation, such as choosing an input capacitor larger than the reference circuit? Yes 23. The output capacitor should be as large as possible. Teacher, you said that a large output capacitor will cause the module to fail to start and work? If the output capacitor is too large, it may cause protection during startup 24. Is the output capacitor more stable as it is larger Too large an output capacitor will cause poor startup or excessive overshoot current 25. Recommend a chip with built-in Schottky Schottky is generally not built-in, and built-in ones generally use synchronous rectification 26. Do power protection circuits generally choose tantalum capacitors? It depends on the specific situation27. Is the zero-point phase curve a graph of the data simulated by your own software design? Some chips have simulation, and other instruments can be used to test28. How to prevent abnormal oscillation of switching power supplies such as DC/DC converters? Is phase compensation required? This requires some understanding of phase compensation. Please contact me for details29. How to choose Schottky diodes? Mainly consider the withstand voltage and current30. What is the role of pre-bias? Is it okay to ignore it? No, it must be considered

• Product model replacement, does Rohm have such a product

31. Regarding the PCB layout of DC-DC, will Rohm provide a layout guide Yes32. Is there an alternative model to LM2596? This is a very old product. Our company has many chips with this function. 33. Can Rohm provide design and simulation tools for DC/DC? Some products do. Please refer to the website. 34. What is the input range of the ROHM DC/DC converter? Is the output adjustable? There are many types of products, and the output is generally adjustable. 35. Can you recommend a DC/DC converter with 12V input and 3.3V output and a maximum output current of 1.5A? There are many such products. You can pay attention to the ROHM official website or contact the relevant ROHM sales. 36. Does Rohm have a DCDC converter suitable for elevators? The DC voltage is required to be 450-700V, the DC current max value is 10A, and the output power is about 4KW. Please refer to the information on our official website. 37. Is ROHM's DC/DC digitally controlled or analog controlled? Yes 38. Is Nano Energy technology a ROHM patent? Yes 39. Are there any DCDC devices with built-in inductors and better EMI? Our company has such modules 40. Does Rohm currently have PFM DC-DC? Yes, please refer to our website 41. Do you have high-power modules? Specially designed for large-scale FPGA power supply Yes, please contact us 42. Are there any non-isolated 80-270Vac wide voltage input, 12V and other low-voltage DC output chips? The peripheral circuit should be simple Yes, please refer to our official website for details 43. Does Rohm have DC/DC isolation modules? What is the power supply range and current range? Yes, please see our website for details 44. Is there a corresponding DEMO board for display Yes, please visit the exhibition held by our company for details, or contact our sales staff 45. Does ROHM have a 110VDC input module for trains There are power modules

• The following questions are answered by the lecturer. Please click on the live review video above. There is the lecturer's contact information at the end. You can follow up through the contact information.

45. DC/DC module. We used Jinyangsheng's module before. Because our circuit does not involve AC, we use it more. May I ask, is the ROHM DC/DC converter also a module? How much power can ROHM achieve? Is DC/DC boost or buck? What is the range of boost and buck? Compared with other DC/DC module circuits, Rohm's DC/DC converter has life advantages in efficiency and volume life? DC step-down circuit, is there a product catalog? I want to know 46. DCDC is generally the focus of EMC testing. How to ensure EMC during design? When encountering EMC problems, how to determine whether it is a DCDC problem and how to deal with it? 47. Looking for a replacement for TPS61098. TI is too expensive to use ICs! ! ! ! 48. Previously, there was a power supply requirement of 2~4V output and 70A current. After considering the solutions of various companies, a multi-channel current sharing solution was finally selected. However, this solution itself is relatively complicated. Does ROHM have a good multi-channel current sharing solution in this regard? Or other solutions that can meet the above requirements? 49. How to minimize noise in DC/DC design? Is there a special auxiliary circuit? 50. How to get a DC-DC circuit with relatively small power ripple, relatively small interference to other circuits in the system, and relatively stable and reliable?

51. Two dry cell batteries are used for IoT module. Which chip is suitable? GPRS and NB modules

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