12 volt power supply circuit diagram using LT3845

Description: Burst Mode operation maintains high efficiency at light loads by reducing IC quiescent current to 120 µA. Light load efficiency is also improved with the reverse inductor current inhibit function, which supports discontinuous operation. Additional features include an adjustable fixed operating frequency that can be synchronized to an external clock for noise-sensitive applications, gate drivers capable of driving large N-channel MOSFETs, a precision undervoltage lockout, 10 A shutdown current, short-circuit protection, and a programmable soft-start. This 12 V power supply project will require an input voltage range between 20 and 55 volts and will deliver a maximum output power of 75 watts at 12 volts output voltage. Using the LT3845 high voltage controller, various power applications can be designed, as this controller accepts a wide input voltage range between 4 and 60 volts and can provide a maximum output voltage of around 36 volts. Additionally, the LT3845 features an adjustable constant frequency from 100 kHz up to 500 kHz.

The described power supply circuit utilizes the LT3845 high voltage controller, which is tailored for high-efficiency operation in applications requiring significant power management capabilities. The Burst Mode operation of the LT3845 is particularly beneficial for applications with variable load conditions, as it minimizes the quiescent current to just 120 µA during light load situations. This feature enhances overall efficiency, especially in battery-powered or energy-sensitive devices.

Incorporating a reverse inductor current inhibit function allows for discontinuous operation, further optimizing efficiency under light load conditions. An adjustable fixed operating frequency is a critical feature, enabling synchronization with external clocks, which is essential for noise-sensitive applications where electromagnetic interference (EMI) must be minimized. The capability to drive large N-channel MOSFETs through robust gate drivers ensures that the circuit can handle substantial load currents effectively.

The precision undervoltage lockout feature safeguards the circuit by preventing operation below a specified voltage threshold, thereby protecting sensitive components from potential damage. The inclusion of a 10 A shutdown current capability and short-circuit protection enhances the reliability and safety of the design, making it suitable for a variety of applications.

The circuit is designed to operate within an input voltage range of 20 to 55 volts and is capable of delivering a maximum output power of 75 watts at a regulated output voltage of 12 volts. The LT3845's flexibility is further demonstrated by its acceptance of an input voltage range from 4 to 60 volts and the ability to provide an output voltage of up to 36 volts, making it versatile for numerous power supply designs. The adjustable constant frequency operation, ranging from 100 kHz to 500 kHz, allows for optimization of performance based on the specific requirements of the application. Overall, this power supply circuit exemplifies advanced design techniques in power management, ensuring efficiency, reliability, and adaptability across various operational scenarios.Burst Mode operation maintains high efficiency at light loads by reducing IC quiescent current to 120 A. Light load efficiency is also improved with the reverse inductor current inhibit function which supports discontinuous operation.

Additional features include adjustable fixed operating frequency that can be synchronized to an external clock fo r noise sensitive applications, gate drivers capable of driving large N-channel MOSFETs, a precision undervoltage lockout, 10 A shutdown current, short-circuit protection and a programmable soft-start. This 12 power supply project will require an input voltage range between 20 and 55 volts and will deliver a maximum output power of 75 watts at 12 volts output voltage.

Using the LT3845 high voltage controller you can design various power applications, because this controller accepts a wide input voltage range between 4 and 60 volts and can provide a maximum output voltage around 36 volts. Also LT3845 has an adjustable constant frequency from 100kHz up to 500kHz.