Simple Switching Regulator Circuit designed by using LM 5007 IC From Texas Instruments. The LM 5007 is an Integrated step down switching Regulator which has all necessary system required for making a cost effective and reliable switching regulator circuit. The IC is available is VSSOP-8, WSON-8 package and has a lot built in feature like thermal shutdown, under voltage lockout, duty cycle timing current limits etc.
This IC LM5007 has a feature that allows the operating frequency to remain relatively constant with load and input voltage variation. This circuit is suitable for Step down conversions on Semi Regulated and Fully regulated supply rails. By using the integrated power MOSFET this IC can deliver up to 500 mA DC load current with exception efficiency and low input quiescent current.
|1.||U1 IC||LM 5007||1|
Construction and Working
The LM 5007 IC contains an internal high-voltage bias regulator. Here the input pin Vin can be connected directly to line voltage from 12V to 75V. Maximum output current 700mA with the indicated rating the circuit is designed for an output voltage of 10V. The output voltage can be adjusted using R3 and R4. C1 and C5 are polyester capacitors, and C1 must be rated at least 100V, R5, and C5 from a filter network. R1 resistor act as an ON timer and the R3 resistor act as an OFF timer current limit.
The output voltage of this regulator can be adjested using the resistor R3 and R4. For the given value of R3 and R4 in the circuit diagram the output voltage will be 10V. Resistor R1 sets the switch on time and C4 is the boost strap capacitor . Resistor R2 determines the variation of OFF time and C3 is a decoupling capacitor. The equation of the output voltage,