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Regulated MOSFET Power Supply Device

IP.com Disclosure Number: IPCOM000077511D
Original Publication Date: 1972-Aug-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 3 page(s) / 51K

Publishing Venue

IBM

Related People

Beilstein, KE: AUTHOR [+2]

Abstract

Lateral transistors and Schottky diodes may be combined with logic circuitry in a semiconductor chip to provide a low-cost power supply for a small computer. Alternatively, the power supply may be incorporated as a part of a complex function in an information handling system fabricated in large scale integration. Fabrication of the lateral transistors and Schottky diodes is readily compatible with the processing technology for forming the logic circuit.

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Regulated MOSFET Power Supply Device

Lateral transistors and Schottky diodes may be combined with logic circuitry in a semiconductor chip to provide a low-cost power supply for a small computer. Alternatively, the power supply may be incorporated as a part of a complex function in an information handling system fabricated in large scale integration. Fabrication of the lateral transistors and Schottky diodes is readily compatible with the processing technology for forming the logic circuit.

A semiconductor chip 10 may be connected at an external pad 11 to an AC power supply 12 through an external resistor 14. The pad 11 is connected to a plurality of lateral transistors 16 whose base and emitters are connected together. The transistors 16 clamp the voltage in the negative direction at 0.7 volt and limit the positive voltage to a maximum of 45 volts at the input, provided the transistors 16 have thick oxide to avoid the high stresses at the input to the chip. The output from the transistors 16 is provided to a diffused resistor 18 which may be tapped at one or more points for different voltage levels. A Schottky diode 20 serves as a filtering element when combined with an external capacitor 22 connected to a pad 21. Current flows into the capacitor 22 which cannot discharge when the input waveform drops in value. The capacitor 22 remains charged near the peak voltage swing of the waveform at the pad 11. More than one Schottky diode 20 can be used if better ripple control is desired. For each additional diode 20, an additional capacitor 22 is used and added to other pads as desired. As few as two pads and two active elements can be combined to achieve various power supply levels and low ripple.

The magnitude of the resistor 14 depends upon the amount of power active elements can be combined to achieve various power supply levels and low ripple.

The magnitude of the resistor 14 depends upon the amount of power re...