Multiple output dynamically regulated charge pump power...

Details Multiple output dynamically regulated charge pump power... Multiple output dynamically regulated charge pump power...

2001-10-09

2003-11-04

Han, Jessica (Department: 2838)

Electric power conversion systems

Current conversion

With voltage multiplication means

C363S124000, C323S267000, C323S288000, C327S589000, C307S110000

Reexamination Certificate

active

06643151

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to DC/DC power supply controllers, and more particularly to regulated charge pump power converters for integrated power management systems.
BACKGROUND
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.
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 current from the batteries is unsuitable for directly powering the electronics of the portable electronic device. For example, the voltage level from the batteries may differ from the voltage level required by the device. In addition, some portions of the electronics may operate at a different voltage level than other portions, requiring different energy source voltage levels. Also, batteries are unable to respond quickly to rapid fluctuations in current demand.
The typical arrangement is shown in
FIG. 1
for a portable electronic device
10
that includes an energy source
12
, such as the one or more batteries, and a load device
14
, such as the electronics that require electrical power. Interposed between the energy source
12
and the load device
14
is a power supply
16
that may perform a number of functions. For example, a power converter
20
, depicted as integral to the power supply
16
, provides the necessary changes to the power from the energy source
12
to make it suitable for load device
14
.
The power supply
16
may also perform functions other than power conversion. For example, protecting the energy source
12
, load device
14
and/or power converter
20
from damage by a sustained high electrical current may require electrically disconnecting the energy source
12
from the rest of the portable electronic device
10
. As another example, the power converter
20
may require assistance during start-up.
Regarding the types of power conversion required, the power converter
20
may “step up” (i.e., boost) or “step down” the voltage. That is, the converter
20
may increase or decrease the output voltage V
OUT
provided to the load device
14
with respect to the input voltage Vs from the energy source
12
. The power converter
20
may also store an amount of energy to satisfy a brief spike or increase in demand by the load device
14
that the energy source
12
is unable to provide.
The power converter
20
may also regulate the output voltage V
OUT
, keeping it close to the desired output voltage level and reducing rapid fluctuations that may cause detrimental noise or cause undesirable performance of the load device
14
. Such fluctuations may occur due to changes in demand, induced noise from external electromagnetic sources, characteristics of the energy source
12
, and/or noise from other components in the power supply
16
.
Although power converters
20
provide many benefits, existing power converters
20
also place undesirable performance constraints on portable electronic devices
10
. The specific attributes of generally known power converters
20
are discussed below along with the types of constraints generally encountered.
Many generally known power converters
20
are optimized for a specific energy source
12
and a specific load demand from the load device
14
. The power converter
20
may not accommodate, or only accommodate inefficiently, variations in the voltage and current characteristics of the energy source
12
and/or the load device
14
. For example, some types of power converters
20
cannot provide an output voltage V
OUT
that is higher than the input voltage V
S
and/or their efficiency is related to how close the input voltage V
S
is to the required output voltage V
OUT
. In addition, some power converters
20
are incapable of providing medium power levels such as 0.5-1.0 W. Moreover, generally known power converters
20
have a design that will only operate within a narrow range of input voltages, output voltages and power capacities.
Additionally, as will be discussed below with regard to
FIG. 2
, some power converters
20
achieve an acceptably regulated output voltage V
OUT
only through inefficient voltage regulators.
In other instances, voltage regulation by the power converter
20
is inadequate for the needs of the load device
14
. For example, the nominal output voltage V
OUT
may vary due to variations in the input voltage V
S
, variations in the temperature of the power converter or the output current drawn by the load device
14
. Also, even if V
OUT
is at an acceptable nominal output level, the power converter
20
may undesirably oscillate about the nominal output voltage V
OUT
. This voltage ripple V
RIP
is defined as the range of the oscillations about the nominal output voltage V
OUT
and may impair or preclude proper operation of the load device
14
.
Therefore, existing power converters
20
do not efficiently provide on demand the required power to a load device, nor adjust to variations in the energy source and load device to provide a stable V
OUT
.
Furthermore, existing power converters
20
do not operate with low input voltage levels, such as a sub-one volt input voltage V
S
. The existing power converters
20
usually require an operational bias voltage that is typically comparable to the output voltage demands of the load device
14
, which are generally greater than one volt. Also, a certain amount of noise is superimposed on the input voltage V
S
by external and internal sources. When the input voltage level V
S
is low, this noise may become relatively significant, degrading or precluding operation of the power converter
20
.
One implication of requiring an input voltage of greater than one volt is that an otherwise desirable single cell battery, or an alternative source of power, may be inappropriate as an energy source
12
for the device
10
. For example, the nominal voltage supplied by certain electrochemical batteries or alternative sources of power may be below one volt, or have a voltage characteristic that decreases as their stored charge decreases. Such batteries have a significant amount, and perhaps a majority of, their stored energy, which is retrievable only at a sub-one volt level. Consequently, the service life of the battery in a portable electronic device
10
is limited by the inability of the device to operate with a sub-one volt input voltage V
S
from the battery. As a result, batteries are discarded with a significant amount of charge or “life” still left in them. Achieving additional service life by incorporating additional batteries into the device
10
increases the size and weight of the device
10
.
Therefore, many existing power converters do not operate (or operate desirably) with a sub-one volt input voltage.
Furthermore, even if a power converter
20
can continuously operate at a sub-one volt input voltage V
S
, generally a higher input voltage level (i.e. over 1 volt) is required to start the power converter
20
. That is, the converter requires a higher input voltage at the start-up phase than is necessary for continuous operation (e.g., 0.4 V higher). Therefore, the power converter
20
must be continuously operated once the minimum start-up input voltage is reached, thus consuming power, in order to enhance the amount of energy that is retrieved from the energy source
12
.
For the start-up phase, an external start-up circuit (such as a Schottky diode) is often added to the existing power converters
20
. The start-up circuit assists in overcoming the

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