LM2671 series voltage regulator is a monolithic integrated circuit manufactured by LMDMOS process. These regulators provide all the active functions of step-down (step-down) switching regulators, capable of driving 500ma load current with excellent line and load regulation. These devices are available in 3.3V, 5v, 12v fixed output voltage and adjustable output versions.
Typical Application
These regulators require a minimum number of external components and are simple to use, including patented internal frequency compensation, fixed frequency oscillators, external shutdown, soft start, and frequency synchronization. The LM2671 series operates at a 260 kHz switching frequency, thus allowing a smaller size filter assembly than is required for what is a low frequency switching regulator. Because it's very efficient. 90%), traces of copper on the printed circuit board are the only heat sink required.
Functional Block Diagram
The standard series of inductors used with the LM2671 is available from several different manufacturers. This feature greatly simplifies the design of switch-mode power supplies using these advanced ics. Also included in the data sheet is a guide to selectors for diodes and capacitors operating in switching mode power supplies.
The LM2671(oscillator) can be run in sync with an external oscillator using a synchronization pin (pin 3). By doing so, the LM2671 can operate at frequencies higher than the standard frequency of 260 kHz. This reduces the size of the inductor and output capacitor. As shown in the figure below, the signal applied to the RC filter at the synchronization pin causes the device to synchronize with the frequency of that signal. For peak-to-peak amplitudes of 3v or greater, 1-kΩ resistance and 100-pF capacitance are appropriate values
