US 5,734,291 A · Power saving technique for battery powered devices

Abstract

An integrated circuit voltage converter containing a capacitive charge pump performing DC to DC conversion is disclosed which detects, either automatically or by an external signal, the onset of a low power consumption situation and switches to a low power consumption mode. In one embodiment, the low power consumption mode is accomplished by reducing the operating frequency of the charge pump. In another embodiment, the switching transistors used to switch the capacitors in the charge pump during a low power consumption mode are smaller than those transistors used to switch the capacitors during its normal operating mode. In another embodiment, the DC to DC converter switches back and forth between a high frequency (burst) mode and a low frequency (low power) mode at intervals. In another embodiment, a combination of the power reduction techniques is used. Various techniques for detecting when a low power consumption mode is appropriate are also described.

Claims21

Dependent claims

An integrated single-chip circuit comprising:

a switching charge pump which receives a first voltage from a power supply and outputs a second voltage different from said first voltage, said charge pump incorporating switching transistors which draw an operating current from said power supply;
an oscillator connected to said switching transistors within said charge pump for controlling an operating frequency of said charge pump;
and
a low power consumption detection circuit for detecting when a low power consumption mode of said charge pump is appropriate and, in response to such detecting, for causing said switching transistors in said charge pump to draw less current from said power supply, said low power consumption detection circuit comprising:
an impedance in series between a load and a terminal of said charge pump, wherein a current through said load is reflected by a current through said impedance;
and
a detector for determining a voltage drop across said impedance and for generating a signal reflecting whether a current into said load is below a threshold current.

4 more elements

A method for lowering the power consumption of a switching type charge pump comprising the steps of:

receiving a voltage from a power supply into said charge pump;
detecting the onset of a low power consumption mode by passing current flowing from said charge pump into a load through an impedance in series between said load and a terminal of said charge pump, wherein the current through said load is reflected by the current through said impedance, determining a voltage drop across said impedance and generating a signal reflecting whether said current into said load is below a threshold current;
controlling an oscillator to output an operating frequency in response to said detecting;
driving switching transistors within said charge pump with said operating frequency;
and
causing said switching transistors within said charge pump to draw less current from said power supply connected to said charge pump by changing said operating frequency of said oscillator.

3 more elements

Dependencies are inferred from the claim text.

Power saving technique for battery powered devices

Life of this patent

Power saving technique for battery powered devices

Life of this patent

Abstract

Claims21