Synchronous BUCK power supply

      The H4022 is a high-performance DC-DC synchronous buck constant voltage/constant current controller manufactured by Dongguan Huihai Semiconductor Co., Ltd. This chip integrates a 40V withstand voltage MOSFET, capable of handling input voltages up to 38V while supporting continuous output current up to 4A, ensuring its applicability in various power supply environments. The H4022's output voltage range is adjustable from 2.5V to 24V, achievable through simple voltage divider resistor adjustment, ensuring power supply flexibility. The chip employs a high-side current-mode control principle, providing fast dynamic response and high efficiency, while a fixed 170kHz switching frequency helps reduce electromagnetic interference. Furthermore, the H4022 features comprehensive protection functions including short-circuit protection, over-temperature protection, and under-voltage protection, ensuring the safe and stable operation of the power system. Optimized current sensing design and enable control functions further improve overall efficiency and ease of power management. The chip uses an ESOP-8 package and features a power heat dissipation pad on the bottom, effectively improving heat dissipation performance. The H4022 is suitable for various applications such as car chargers, lighting, portable device power supplies, and battery chargers, making it an ideal power management solution for electronic device design. It is inexpensive, with bulk pricing around 0.6 RMB.
        The synchronous buck architecture offers several significant advantages in power management, making it the preferred solution for high-efficiency electronic designs. This architecture achieves high efficiency by using two switching devices simultaneously—the upper and lower transistors—as it reduces the power consumption of individual devices during conduction, thereby reducing the overall system's thermal load. Synchronous rectification technology also helps reduce output voltage ripple, providing a smoother voltage output, while enhancing load regulation to ensure stable voltage levels under varying loads. Furthermore, synchronous buck converters typically have fewer external components, simplifying the design process and helping to reduce the physical size of the solution, making them particularly suitable for portable or space-constrained applications. They can also handle a wide range of input voltages, easily integrate soft-start and various protection functions such as overcurrent, overtemperature, and undervoltage protection, thereby improving system reliability and stability. These features of the synchronous buck architecture make it particularly outstanding in applications requiring high current output, while also improving electromagnetic compatibility, making it an indispensable part of power supply solutions.
Thanks to Mr. Huang Jinyu, Sales Manager of Dongguan Huihai Semiconductor Co., Ltd., for his support. For chip procurement, please contact VX: 13924924865.
Recommendation: Avoid 4A output as the chip will overheat; the chip temperature reaches 83°C at 3A output.
1. An SS36 Schottky diode is used at the input for reverse connection protection. Its function is to protect the chip from damage if the input power is reversed. The advantage of using a diode is its low price, but the disadvantage is slightly higher power loss.
2. Four 10uF, 35V X5R MLCC capacitors are used for the input. According to the official reference calculation document, the minimum input capacitance is 47uF. Therefore, four 10uF, 35V MLCC capacitors and one 0.1uF, 50V X7R MLCC capacitor are connected in parallel. These five capacitors should be placed close to the VIN pin during PCB layout.
Notes: X7R and X5R capacitors indicate their temperature tolerance; X5R represents -55°C to +85°C, and X7R represents -55°C to +125°C.
3. Inductor selection: Using the official table, input voltage, output voltage, and current were entered. After calculation, a reference inductance of 20.6uH was chosen. However, this value is unavailable, so a 22uH inductor was selected. Shielded inductors are preferable to reduce EMI and improve stability and safety. Since a 22uH inductor was unavailable, a 47uH/3A inductor was used.
4. Output capacitor selection: Four 22uF, 25V X5R capacitors were chosen. The table references 1000uf/16V electrolytic capacitors. Due to the higher equivalent ESR of electrolytic capacitors, four 22uF capacitors and one 0.1uf MLCC capacitor were ultimately selected.
5. The feedback voltage sampling resistor uses 31.6K, and 10k±1% forms the feedback network. These two values ​​are readily available; alternatively, values ​​from the reference table can be used.
6. A red LED is included as a power indicator, and a 4.7K current-limiting resistor is used.
II. Layout Requirements
Official Layout Recommendation:
Based on the reference guidelines, the following is my personal layout; please forgive any shortcomings. This prototype uses immersion gold color silkscreen printing.
2.1 Due to the inherent ±1% error of the resistors, the measured output voltage accuracy is ±1%.
2.2 No-load ripple: Due to the limited equipment and lack of a load cell, the measured no-load ripple is 10-20mV. For chips under 1 unit, this is considered a high-performance chip.
24V input, 3A load, official test output ripple. (My board layout differs slightly from the official board layout.)
Ripple at 12V input, 5V output.
2.3 Short circuit protection: Please refer to the video below.
2.4 Datasheet, calculation tables are in the attachment below.