MIC3808BM

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Power management integrated circuits (PMICs) are designed to simplify the process of managing various power needs and reducing system complexity. The MIC3808BM is one of a family of such devices, designed to meet the needs of offline switcher applications, including ac-dc and dc-dc conversion. This article aims to discuss the key features of this IC, its application field and working principle.

MIC3808BM Overview

The MIC3808BM is an offline buck-switching regulator IC from the MIC3808 family. It is a monolithic integrated circuit (IC) that integrates both a power MOSFET and a driver. It is designed to provide an optimum solution for driving power transistors in conventional AC/DC buck-switching power supplies. Its built-in driver transistor is also provided for easy control of the load current. The MIC3808BM generally works in buck mode as its name implies, meaning it reduces a supply voltage to a lower level. It is intended to be integrated into other power management products such as AC/DC power supplies.

Features

The MIC3808BM is a high-performance, high-efficiency PMIC designed for low-power applications. It features a wide input supply voltage range making it an ideal choice for universal ac line applications. Other features include a low-cost, small footprint, and low-profile package. It also features peak current mode control, integrated soft-start and output overcurrent protection. The peak current mode control ensures reliable regulation of output voltage over the specified load range. The integrated soft-start helps in reducing inrush current at turn-on. The output overcurrent protection ensures the safe operation of the device even when the output current increases beyond the rated limit.

Application Field

The MIC3808BM is suitable for a broad range of low-power ac/dc conversion applications. It is used for driving power transistors in conventional AC/DC buck-switching power supplies, typically for portable electronic applications. These can include laptop/notebook computers, mobile phones, digital cameras, MP3 players, and any other low-power AC/DC power supply designs. It is also suitable for driving dc/dc converters in isolated and non-isolated configurations.

Working Principle

The MIC3808BM is a current mode buck switcher operating at a fixed frequency of 250 kHz. It utilizes a peak current mode control of the internal power MOSFET switch, which ensures reliable operation even with rapidly changing load currents. The MIC3808BM is designed to work in a wide input supply voltage range, from the universal ac line level (85 to 265 Vac) to a 20 Vdc level. In this configuration, the IC senses the peak current of the power MOSFET and turns it off once the predetermined peak current level is exceeded. This current-limited switch with the PWM control provides a good power conversion efficiency even over the full load range.

When working in buck mode, the converter reduces the input voltage to a lower level as decided by the user and regulates the same output voltage over varying loads. The buck converter starts up with the help of an integrated soft-start process. This process is designed to reduce the inrush current at turn-on, thereby protecting the components from over-current and over-voltage levels. Additionally, the device also features overcurrent protection, which ensures the safe operation of the device even when the output current increases beyond the rated limit.

Conclusion

The MIC3808BM is an ideal choice for low-power offline switcher applications, including ac-dc and dc-dc conversion. The device is suitable for a wide range of applications, from universal ac line applications to dc/dc converters. The MIC3808BM features a wide input supply voltage range and peak current mode control, providing reliable operation even with rapidly changing load currents. The integrated soft-start makes it suitable for applications requiring low-inrush current turn-on. In addition, it features output overcurrent protection, ensuring the safe operation of the device.

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