UC3844BDR2G Integrated Circuits (ICs)

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The UC3844BDR2G series of integrated circuits from Texas Instruments is a medium-performance direct current-to-direct current (DC-to-DC) switching controllers. It is designed to provide high efficiency and reliable operation for switch-mode power supplies for medium- and low-power applications. The device can be used in both off-line and dc-to-dc configurations.

Features

The key features of the UC3844BDR2G include:

• Operating temperature range from -40°C to +150°C;
• Operating voltage range from 4.5V to 32V;
• Integrated over-temperature, over-current, and under-voltage protection circuits;
• High voltage, low power consumption CMOS process;
• High switching frequency for reduced component size;
• Selectable frequency control mode;
• Designed for simple current-mode switching power supplies.

Application fields

The UC3844BDR2G offers many advantages to those who work with power supplies, including improved efficiency, cost savings, smaller circuit designs, and greater system flexibility. It is particularly useful when used in applications such as:

• Modems and routers;
• LED lighting systems;
• Air quality monitors;
• Security systems;
• Computer back-up power supplies;
• Portable consumer electronics;
• Point-of-sale (POS) equipment;
• Automotive and industrial applications.

Operation principle

The UC3844BDR2G device uses Pulse Width Modulation (PWM) to switch an inductive load or synchronous rectifier to obtain low ripple with high efficiency. This switching process is possible thanks to the device\'s Pulse Frequency Modulation (PFM) to regulate the fundamental switching frequency. Frequency control requires a variable frequency oscillator connected to the CTRL pin. The oscillator provides the characteristic frequency of the power supply.

The UC3844BDR2G acts as a voltage-mode pulse-width modulator that senses the output voltage through the sense resistor connected between the VCC and the Output pins. When the output voltage decreases, the voltage at the Sense input will increase and the PWM duty cycle will increase. This higher duty cycle will cause an increase in the inductor current and thus a recovery in the output voltage. The PWM duty cycle will remain high until the voltage resumes its stabilized value.

The internal voltage loop gain of the device is defined by an external resistor divider so that the range of the duty cycle can be accurately adjusted. This feature is important for obtaining low line and load regulation. In addition, the standby function blocks the internal biases and reduces quiescent current to a few µA.

Conclusion

In conclusion, the UC3844BDR2G series of DC-to-DC switching controllers offers efficient and reliable operation for various medium- and low-power applications, such as modems, routers, LED lighting systems, air quality monitors, security systems, computer back-up power supplies, portable consumer electronics, Point-of-sale (POS) equipment, and automotive and industrial applications. It features a variable frequency oscillator and an adjustable duty cycle through an external resistor divider to regulate the output voltage and ensure high efficiency and low voltage ripple.

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