Progressive start-up circuit for activating a charge pump

Abstract

A charge pump power converter efficiently provides electrical power by dynamically controlling a switch matrix of the charge pump. Instead of open-loop oscillator-based control, a dynamic controller provides power upon demand by sensing the output voltage and changing the operating frequency of the charge pump in response. Moreover, this closed-loop dynamic control intrinsically voltage regulates the output voltage of the charge pump power converter without the inefficient addition of a step-down voltage regulator, downstream of the power converter. In addition, this closed-loop dynamic control allows for maintaining a desired output voltage even with variations in the input voltage. Also, the dynamic control accommodates the advantages of using ultra-capacitors in the charge pump. The power converter is capable of operating with a sub-one volt input voltage incorporating low-threshold, low on-resistance power MOSFET switches in the switch matrix of the charge pump. A progressive start-up circuit further allows the power converter to start from a discharged state even with a sub-one volt input voltage.

Description

[0001] The present invention relates to DC / DC power supply controllers, and more particularly to regulated charge pump power converters for integrated power management systems.[0002] Advances in electronics technology have enabled the design and cost-effective fabrication of portable electronic devices. Thus, usage of portable electronic devices continues to increase both in the number of products available and the types of products. Examples of the broad spectrum of portable electronic devices include pagers, cellular telephones, music players, calculators, laptop computers, and personal digital assistants, as well as others.[0003] The electronics in a portable electronic device generally require direct current (DC) electrical power. Typically, one or more batteries are used as an energy source to provide this DC electrical power. Ideally, the energy source would be perfectly matched to the energy requirements of the portable electronic device. However, most often the voltage and c...

AI Technical Summary

Benefits of technology

0177] A power converter 40A consistent with the invention may be incorporated in a wide range of products. For example, a power converter 40A taking advantage of the small size achievable with integrated circuits and low power consumption properties described above may advantageously be incorporated into a battery package to enhance battery service life and energy and amplitude on demand.

0178] Moreover, a power converter 40A consistent with the invention, whether incorporated inside an energy source 12 or in a load device 14 utilizing an energy source 12, would improve or enable a wide range of portable electronic devices 10. For example, the reduction in size and weight of an energy source 12 would allow less intrusive medical diagnostic, energy-delivery, or actuated medicine delivery devices, whether worn or implanted.

0179] In addition, portable electronic currently powered by batteries or similar energy sources 12 may be improved by incorporating the power converter in accordance with the invention. In portable communication devices and portable audio devices, for instance, improved service life may be obtained through the increased efficiency, and performance may be enhanced by lowering the power converter 40A operating frequency, and thus the noise, when allowed to do so by a decreased demand.

Problems solved by technology

The disadvantage of the short self-discharge time for electronic capacitors means that oscillator-based charge pumps 20 must operate at duty cycles that are between the rate in which the electronic capacitor can be charged and discharged and the rate at which the electronic capacitor will self-discharge.

Consequently, known oscillator-based charge pumps 20 cannot take advantage of ultra-capacitors and similar high storage devices that have self-discharge times measured in weeks or months.

Moreover, as will become apparent below, the power converter 40A may readily be implemented as an integrated circuit and thus be of small size and cost.

For example, the energy source may have a safety limitation on the amount of current that can be provided, perhaps for a certain duration.

This represents situations where the various protection measures may result in a situation where the power converter needs to be restarted.

In addition, the Schottky diode consumes power during normal operation of the oscillator-controlled power converter 20, thereby reducing efficiency.

This is due to the non-compensated nature of the comparator.

However, the current capability of this one small MOSFET is insufficient to charge the load capacitor C.sub.L.

For example, common-mode signals may be induced noise on the inputs.

Consequently, devices using photovoltaic cells may often be inoperable due to insufficient light, may have to limit functionality to remain within the typical amount of available power, and / or have to increase the surface area devoted to photovoltaic cells.

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