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DUAL COMPLEMENTARY VOLTAGE OUTPUT DC TO DC CONVERTER

IP.com Disclosure Number: IPCOM000005658D
Original Publication Date: 1987-Oct-01
Included in the Prior Art Database: 2001-Oct-24
Document File: 1 page(s) / 45K

Publishing Venue

Motorola

Related People

Michael F. Breske: AUTHOR

Abstract

The illustrated DC-DC converter uses a minimum number of component parts, in particular, only one coil, to achieve a dual complementary voltage output. This circuit is ideally suited for use with a microprocessor because a simple software routine can be used to generate the input waveforms Fl and F2. Variations in output voltage and current capability can easily be obtained by varying the input waveforms, At tq, P-channel transistor 01 and N-channel transistor Q2 are conducting and the inductor is charging (i.e., its current is increasing). At t2, Ql stops conducting and the voltage across the inductor will increase at the rate of L dildt, thereby inducing a negative voltage at the drain of Ql. This induced voltage causes capacitor Cl to charge negatively through diode Dl. If the inductor rings, the positive portion of the ring will charge capacitor C2 through diode D3. At tl, both Ql and Q2 are conducting and the inductor will charge again At te, Q2 stops conducting causing a positive voltage (relative to +V) to be induced at the drain of Q2. This in- duced voltage causes C2 to charge positively through diode D4. If the inductor rings, the negative portion of the ring will charge Cl through diode 02. At t., the waveform is repeated.

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MO7VROLA Technical Developments Volume 7 October 1987

DUAL COMPLEMENTARY VOLTAGE OUTPUT DC TO DC CONVERTER

by Michael F. Breske

   The illustrated DC-DC converter uses a minimum number of component parts, in particular, only one coil, to achieve a dual complementary voltage output. This circuit is ideally suited for use with a microprocessor because a simple software routine can be used to generate the input waveforms Fl and F2. Variations in output voltage and current capability can easily be obtained by varying the input waveforms,

At tq, P-channel transistor 01 and N-channel transistor Q2 are conducting and the inductor is charging
(i.e., its current is increasing). At t2, Ql stops conducting and the voltage across the inductor will increase at the rate of L dildt, thereby inducing a negative voltage at the drain of Ql. This induced voltage causes capacitor Cl to charge negatively through diode Dl. If the inductor rings, the positive portion of the ring will charge capacitor C2 through diode D3. At tl, both Ql and Q2 are conducting and the inductor will charge again At te, Q2 stops conducting causing a positive voltage (relative to +V) to be induced at the drain of Q2. This in- duced voltage causes C2 to charge positively through diode D4. If the inductor rings, the negative portion of the ring will charge Cl through diode 02. At t., the waveform is repeated.

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