Buck converter with parallel switches

Details Buck converter with parallel switches Buck converter with parallel switches

1999-03-01

2001-02-06

Wong, Peter S. (Department: 2838)

Electricity: power supply or regulation systems

Output level responsive

Using a three or more terminal semiconductive device as the...

C323S271000, C323S351000

Reexamination Certificate

active

06184666

ABSTRACT:

FIELD OF THE INVENTION
The invention generally relates to power converters and, more particularly, the invention relates to multiple switch buck converters.
BACKGROUND OF THE INVENTION
Integrated circuits and other circuit elements within electronic devices commonly require an input voltage that is smaller than that supplied by a regulated D.C. power source. For example, an integrated circuit within a computer system may require a powering voltage of about 2.5 volts D.C. from a standard 3.3 volt regulated D.C. source. To that end, voltage regulators have been developed that reduce an input D.C. voltage to a preselected, lower voltage.
Many such prior art regulators, such as linear converters, have a relatively low efficiency (i.e., between about fifty and sixty five percent) when used in high current applications. Accordingly, when used in high current applications, linear converters typically require relatively large heat sinks to dissipate a large amount of heat produced by the voltage reduction process. This heat loss necessarily increases the operating cost of such converters. Moreover, the requirement of a heat sink increases the size and manufacturing cost of each converter.
The art has responded to this efficiency problem by providing switching voltage converters (“buck converters”) that dissipate minimal heat in high current (as well as low current) applications. Accordingly, buck converters typically operate at efficiencies of between about seventy and ninety-five percent. Buck converters typically utilize an inductor and a switch that cooperate to reduce the input voltage to a preselected output voltage. The duty cycle of the switch in buck converters, however, can be greater than about ninety percent. This causes the switch to generate excessive heat, especially when used in high current applications. Accordingly, a large switch with a relatively large heat sink often is utilized to dissipate the excess heat. This necessarily increases the cost associated with producing and operating such buck converters.
SUMMARY OF THE INVENTION
In accordance with one aspect of the invention, a converter for reducing the amplitude of a DC input signal includes first and second switches that each are coupled between an input port for receiving the input signal, and voltage reducing circuitry for reducing the amplitude of the input signal. The two switches are configured so that at least one of the two switches is open at least part of the time that the other is closed, thus reducing the heat generated by either one of the switches. For example, if the switches each open and close once in a preselected time interval, one switch may be open for a first half of that time interval while the other switch may be open for the second half of that time interval. This consequently reduces the need for heat dissipation devices such as, for example, conventional heat sinks. Moreover, the two switches each may be smaller than that which would be used if a single switch were used since their duty cycles are much smaller than that of such single switch. The converter further includes an output port coupled to the voltage reducing circuitry for providing an output signal having an amplitude that is less than that of the input signal.
In accordance with other aspects of the invention, the first switch has a first duty cycle of about fifty percent, and the second switch has a second duty cycle that does not exceed fifty percent. The converter further includes buck conversion circuitry with an inductor for receiving current from one of the first switch and the second switch. In other embodiments, the converter includes an input port filter for filtering noise from the input signal, and an output port filter for filtering noise from the output signal. In other embodiments, the switch is a transistor. In still other embodiments, the converter includes control circuitry for controlling the closing of both the first switch and the second switch.
In accordance with other aspects of the invention, the first duty cycle and the second duty cycle are different. Moreover, the first switch closes at a first time and the second switch opens at a second time, where the first time and the second time are substantially the same time. In still other aspects of the invention, the first duty cycle is out of phase with the second duty cycle. In preferred embodiments, the first duty cycle is greater than about ninety degrees out of phase with the second duty cycle. In yet other aspects of the invention, the first switch is closed at a first frequency and the second switch is closed at a second frequency, where the first frequency is different from the second frequency.


REFERENCES:
patent: 5616945 (1997-04-01), Williams
patent: 5663635 (1997-09-01), Vinciarelli et al.
patent: 5886508 (1999-03-01), Jutras
patent: 5919262 (1999-07-01), Kikinis et al.
patent: 5929692 (1999-07-01), Carsten
patent: 5932995 (1999-08-01), Wagoner
patent: 5994885 (1999-11-01), Wilcox et al.

Affiliated with

Also associated with

Rating

Buck converter with parallel switches does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Buck converter with parallel switches, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Buck converter with parallel switches will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2601828