Sleep-mode-ready switching power converter

Details Sleep-mode-ready switching power converter Sleep-mode-ready switching power converter

1999-08-15

2001-05-15

Riley, Shawn (Department: 2838)

Electricity: power supply or regulation systems

Output level responsive

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

C323S282000

Reexamination Certificate

active

06232754

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to the field of electronic devices, and in particular to switching power-supply converters and regulators.
2. Description of Related Art
Switching converters and regulators are common in the art. Commonly, the terms voltage converter, voltage regulator, DC—DC converters, DC supplies, and so on are used to generically define a device that provides a source of voltage or current that satisfies a given constraint (hereinafter a “controlled” voltage or current source) from an input supply that may or may not satisfy that constraint (hereinafter an “uncontrolled” voltage or current source). The term switching converter, or switching power converter, is used herein for ease of reference; it will be recognized by one of ordinary skill in the art that the principles involved are applicable to devices that provide a controlled voltage, a controlled current, or a combination of both. Generally, a switching converter switches between coupling and decoupling an input supply to a storage device, and the load draws its energy from the storage device. The storage device may store voltage or current, or a combination of both. Controlling the amount of time that the input supply is coupled to the storage device controls the amount of power transferred from the input supply to the load. The particular devices employed determine whether the controlled amount of power is transferred as controlled voltage or controlled current, or a combination of both.
FIG. 1
illustrates an example block diagram of a commonly used switching power converter
100
. The example power converter
100
is commonly termed a “buck converter” or “buck regulator”, and, in particular, a “two-switch buck converter”. Other switching converters are common in the art, the buck converter being selected herein as a preferred paradigm for presenting the principles of switching supplies and the principles of this invention. The switching power converter
100
comprises a first switch S1
110
, a second switch S2
120
, two storage devices L
130
and C
140
, and a switch controller
150
that controls the power transfer from a supply input V
IN
101
to a controlled output V
OUT
103
, via the storage devices L
130
and C
140
. The supply input V
IN
101
and controlled output V
OUT
103
are referenced to a second voltage supply
109
, typically at ground potential. For ease of understanding, the operation of the switching converters herein is described in terms of a controlled voltage output.
Initially, the switch controller
150
closes switch S1
110
, thereby coupling the supply input V
IN
101
to the storage devices L
130
and C
140
. Because the storage device L
130
is an inductor, the current I
L
131
rises continuously from its initial zero level, ideally linearly. This current provides an output current I
OUT
103
′ to a load (not shown), and also transfers charge to the capacitor C
140
, increasing the voltage V
OUT
103
across the capacitor relative to the second supply voltage
109
. The rate of increase in the current I
L
131
is, ideally, linear, and proportional to the voltage across the inductor. Initially, with switch S1 closed, the voltage at node
102
is equal to the input supply voltage, and V
OUT
103
is zero. Therefore, initially, the rate of increase in current I
L
131
is large.
Typically, the switch controller
150
is operated continuously at a fixed frequency of operation, based upon which the values of the storage devices L
130
and C
140
are determined. The proportion of time that switch S1 is on (the “duty cycle”) is used to control the output V
OUT
103
. Ideally, the duty cycle is initially long, to supply sufficient energy to bring the controlled output to its desired value quickly, and then settles to a steady-state value that is related to the ratio of the controlled output V
OUT
103
to the supply voltage V
IN
101
. The example buck converter of
FIG. 1
is a “down” converter, such that the desired value of V
OUT
103
is less than the supply voltage V
IN
101
; switching “up” converters are also common in the art.
At a later point in time, dependent upon the current duty cycle, the switch controller
150
opens the switch S1
110
, decoupling the supply input V
IN
101
from the storage devices L
130
and C
140
. At the same time, S2 is closed, allowing the current I
L
131
to continue to flow, due to the inductance of the inductor L
130
, thereby transferring energy from the first storage device L
130
to the second storage device C
150
, and correspondingly, to the controlled output V
OUT
103
.
At the beginning of the next cycle, the controller
150
closes the switch S1
110
and opens the switch S2
120
, coupling the input supply
101
again to the storage devices L
130
and C
140
. At this time, V
OUT
103
is greater than zero, and therefore the rate of increase in current I
L
131
is less than at the start of the initial cycle, when V
OUT
103
was zero. Thereafter, switch S1 is opened, switch S2 is closed, and current I
L
131
decreases. The rate of decrease of current I
L
131
is proportional to the voltage across the inductor L
130
, which, while S2 is closed and S1 is opened, is equal to the voltage V
OUT
103
. Thereafter, switch S1 is again closed, switch S2 opened, and the cycles continue. The switch controller
150
continually adjusts the duty cycle until the voltage V
OUT
103
reaches the desired controlled voltage level.
The rate of increase in V
OUT
103
is proportional to the difference between the current I
L
131
and the current I
OUT
103
′ drawn by the load. In a steady-state condition, with V
OUT
103
at the desired controlled voltage level, the average current I
L
131
is equal to the average load current I
OUT
103
′. During each cycle, the current increases (S1-on) and decreases (S1-off) about this average load current value. This variance about the average is termed a ripple.
When the current demand decreases, as when the load is placed in a minimal current sleep-mode, the controlled output V
OUT
increases, as the switching converter continues, at least momentarily, to supply the higher current. In response to the overvoltage, the controller
150
decreases the duty cycle of switch S1. The duty cycle is reduced such that the duration of current increase (S1-on) is substantially less than the duration of current decrease (S1-off), and the current I
L
131
through the inductor L
130
decreases below zero as charge is removed from the capacitor C
140
. Thus, with each subsequent cycle, the average current I
L
131
decreases, and the amount of overvoltage decreases. Eventually, the average current I
L
131
decreases to the reduced current demand of the sleep-mode load
103
′, and the controller continues its steady state process of periodically closing the switch S1 to maintain the controlled voltage output V
OUT
103
.
In both the high-current and low-current demand scenarios, the controller
150
controls the switch S1 so as to periodically replenish the energy removed from the storage devices L
130
and C
140
due to the load current I
OUT
103
′ and due to circuit and switch losses, such as the inherent resistances of the inductor L
130
and switches S1 and S2. That is, the controller couples and decouples the input supply
101
to the storage devices L
130
and C
140
to control the amount of power that is transferred to the load associated with the controlled outputs
103
,
103
′. A variety of techniques are commonly employed in the controller to control the switching to provide the controlled output, depending upon the level of precision or accuracy required on the controlled outputs
103
,
103
′. The controller
150
receives appropriate feedback (not shown) to maintain the required precision or accuracy.
As portable electronic systems become increasingly popular, and increasingly capable, the need for placing segments of the system into a “sleep-mode” that consumes minimal power becomes incr

Affiliated with

Also associated with

Rating

Sleep-mode-ready switching power converter does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Sleep-mode-ready switching power converter, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Sleep-mode-ready switching power converter will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2454789