The LM5020 is employed here to design a Boost power supply where the input voltage rail is stepped up to create the output voltage rail. The LM5020 is a versatile PWM controller requiring an external the FET switch which can be sized to fit the output specification. The input voltage, Vin, during the on-time of the switch charges the L1 inductor through the FET to ground. During the off-time of the FET switch the inductor reverses polarity to forward bias the diode D1 to charge the output capacitors to the required output voltage and provide current to the load. The output voltage is set through the voltage divider R6 & R8 and the loop transient response is governed by the resistor capacitor circuit across the feedback pin, VFB, and the compensation pin, COMP, of the controller IC. Output capacitors (C3,C4,C10) are set to limit ripple and noise voltage while the input capacitance limits the noise ripple effects found on the input rail. The softstart ramp is optimized through C7 and the switching frequency is set via R4. Note that M1 in the schematic is shown as Q1 in the layout.
Schematic
Example Schematic Showing Connection for all Components.
Example Schematic Showing Connection for all Components.
