MIC4811YMM

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MIC4811YMM Application Field and Working Principle

The MIC4811YMM is a High Voltage Single Output Current Mode PWM Constant Current LED Driver, manufactured by Micrel Inc. It is specially designed to provide constant current control for high power LED lighting applications.

The MIC4811YMM utilizes an innovative switching current mode architecture, with a patented current sharing scheme, which can maintain the accuracy of the average LED current over a wide range of LED forward voltage. It provides excellent LED brightness stability and uniformity via a tight LED current regulation, with high efficiency and guaranteed performance in a small and cost-efficient package.

The MIC4811YMM features two wide-range input selection modes and two constant-current (CC) feedback modes. The input selection of the MIC4811YMM can either be set to regulate the current from an external resistor (EXTMODE) or with a PWM signal source (PWMV). When EXTMODE mode is enabled, the LED current is regulated by the external resistor. When PWMV mode is enabled, the LED current is regulated by an external PWM signal source.

The constant-current feedback of the MIC4811YMM is an internal or external programmable current-sense amplifier, which can regulate the LED current within ±3%. The amplifier uses a switchable current-sense resistor (Rs) to provide a reference voltage. The voltage across Rs is then buffered and amplified by the current-sense amplifier. The output of the current-sense amplifier is then compared with a reference, and if a difference is detected, the output of the PWM controller is adjusted.

In addition, the MIC4811YMM features various protections, like thermal shutdown protection (TSD), open-LED protection (OPEN), and over-current protection (OCP). The TSD protection monitors the device temperature, and can activate the protective shutdown routine when the device temperature exceeds the upper threshold. The OPEN protection prevents the system from damage from open LED and OCP prevents the over-current from flowing through the LED.

MIC4811YMM is ideal for various high power LED lighting applications, including commercial and industrial lighting, street lighting, residential lighting, and so on. The device provides tight control of the average LED current, as well as high efficiency and excellent thermal performance, which make it a great choice for this application.

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