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Low-Cost Ripple Regulator Power Supply

IP.com Disclosure Number: IPCOM000059657D
Original Publication Date: 1986-Jan-01
Included in the Prior Art Database: 2005-Mar-08
Document File: 2 page(s) / 32K

Publishing Venue

IBM

Related People

Zalph, WN: AUTHOR

Abstract

A technique is described whereby an inexpensive power supply with good regulation provides a single output voltage without the need for a transformer. The circuit functions as a ripple regulator with series pass regulation. When primary input voltage 10 is applied, as shown in the figure, inductor 11 is provided to limit the surge current. Half wave rectifier 12 rectifies the waveform while resistor 13 limits the average current. Resistor 14 raises the gate voltage of power field-effect transistor (FET) 15 so that it is biased on. As the voltage at 16 rises due to the charging of capacitor 17, the voltage at 18 also rises. However, the rise in voltage at 18 is limited due to zener 19. Therefore, the output voltage 20 equals the voltage at 18 minus the voltage drop across transistor 27.

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Low-Cost Ripple Regulator Power Supply

A technique is described whereby an inexpensive power supply with good regulation provides a single output voltage without the need for a transformer. The circuit functions as a ripple regulator with series pass regulation. When primary input voltage 10 is applied, as shown in the figure, inductor 11 is provided to limit the surge current. Half wave rectifier 12 rectifies the waveform while resistor 13 limits the average current. Resistor 14 raises the gate voltage of power field-effect transistor (FET) 15 so that it is biased on. As the voltage at 16 rises due to the charging of capacitor 17, the voltage at 18 also rises. However, the rise in voltage at 18 is limited due to zener 19. Therefore, the output voltage 20 equals the voltage at 18 minus the voltage drop across transistor 27. The voltage at 16 is greater than the voltage at 18 to assure that zener 21 breaks down after zener 18. When zener 21 breaks down, FET 22 begins to conduct, pulling the FET 15 gate down. This turns off FET 15, causing the voltage at 16 to decay as a function of the output current. Resistors 14, 23 and the voltage at zener 21 are set to insure that FET 22 turns off and allows FET 15 to turn back on before node 16 falls below the voltage at 18. Resistor 24 sets the current for zener 19. Resistor 25 provides a direct current path for zener
21. Capacitor 26 eliminates ripple for the zener reference voltage at 18. Transistor 27 is a series pass reg...