Author: maoruixin Technology

Time: June 4, 2021 in the upsurge of China’s new infrastructure led by seven major fields, such as new energy vehicle charging pile, big data center and 5g base station, various input / output devices have higher and higher requirements for power consumption and power density, and buck converter products with small size and high current support have become new market demand. Maoruixin technology has launched a synchronous rectifier Buck Controller with full-featured 110V withstand voltage, lighting the domestic star core fire, helping China’s industrialization and prospering China’s new infrastructure.

On May 25, 2021, USB pd3.1 launched by USB association increased extended power range (EPR). The maximum power is expanded from 100W to 240W, and the maximum allowable voltage is increased to 48V. This upgrade is of great significance. It extends the application range of USB Pd from traditional mobile phones and laptops to portable devices, Internet of things devices, smart home, smart home, smart home, smart home, etc In the fields of communication and security equipment, automobile and medical treatment, USB pd3.1 will become a truly unified power supply standard, which will play an important role in reducing e-waste, promoting the earth’s environmental protection and supporting the interconnection of all things.

Mk9218, the first 110V input synchronous rectifier Buck Controller in China, has won the honor of domestic star core with its new technical advantages. This product can support 110V input voltage up to 48V bus application scenarios. It will be widely used in communication power supply, 48V architecture server power supply, Poe Ethernet power supply, USB pd3.1 and other products.

1. Wide application scenarios

Based on the voltage control mode, mk9218 has high efficiency and excellent transient response. It has an ultra wide input voltage range of 6v-100v, which fully covers the wide input voltage application of 12v-54v industrial voltage. At the same time, it can ensure the safety and reliability of the application scenario in which the maximum transient voltage does not exceed 100V. The application block diagram of mk9218 is as follows:


2. Full function of the product

Mk9218 has precise control and complete functions

  • Multi mode control (shutdown, standby, PFM, FCCM)
  • Frequency adjustable 100khz-1mhz
  • Adjustable slow start and voltage following function
  • Multi chip synchronization function (synci, Synco)
  • Programmable over current protection (OCP)
  • PG function
  • Automatic recovery of OTP and OCP
  • Vin / VCC / boot under voltage protection function
  • Support pre bias startup
  • Ultra small 3.5mm x 4.5mm qfn-20 package
  • Integrated high voltage LDO, support single VIN power supply and automatic switch to external VCC power supply


Multiple modes (shutdown, standby, PFM, FCCM) match various application scenarios: shutdown and standby modes are suitable for battery saving mode, PFM is suitable for light load mode, and FCCM mode is suitable for high ripple and fly-buck scenarios.

Programmable switching frequency adapts to different ripple requirements and inductance limiting system (the figure below shows 12V output, 1MHz switching frequency, output ripple < 10mV);

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Programmable ramp up and voltage following functions can match different application scenarios and adjust the impulse current of the switch to the best;

The synchronous input signal can carry out effective external interleaving control, and the synchronous output signal can effectively reduce the adverse effects such as beat frequency;

Programmable over-current protection can set any over-current point to better protect the system board;

PG function can realize effective timing control and system power on / off logic;

Automatic recovery of OTP and OCP functions can better protect the board and automatically recover after the fault is removed;

Vin / VCC / boot under voltage can effectively ensure the safety of power supply devices;

Supporting pre bias start function can effectively solve the starting problem of instant power failure;

Ultra small 3.5mm x 4.5mm qfn-20 with EP pad package can save the area of cloth board and improve the power density of the whole board.

3. High efficiency

Mk9218 adopts multi-mode (shutdown, standby, PFM, FCCM) to match different application scenarios, so as to ensure the highest power conversion efficiency in different scenarios. At the same time, it effectively improves the work efficiency through precise dead time control, optimized driving current (source 2.5A / sink 3.5A), external VCC power supply, high VIN input and other technical means, The figure below shows the actual test efficiency of 12V (switching frequency 400kHz) and 5V (switching frequency 230khz) output

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4. Strong withstand voltage level

In order to eliminate the customers’ pain points in the communication and industrial fields, mk9218 has a wider VIN withstand voltage level, can adapt to the industrial voltage range of 12v-54v, and the electrical parameters meet the wide temperature range (- 40 ℃ to 140 ℃) (the actual system verifies that – 60 ℃ – 150 ℃ works normally).


5. High reliability

Part of the system in the two major fields of communication and industry in the actual application environment is harsh (wide range of high and low temperature, large electromagnetic interference, unable to quickly maintain, etc.), which requires the system to work continuously for at least ten years, so the reliability of the driver chip has a very high requirement.

Mk9218 has passed the complete JEDEC reliability standard test and severe system reliability test, and works normally and meets the reliability requirements.


With its excellent performance and high reliability, mk9218 was selected and tested by many industrial customers as soon as it was launched.

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