Low power mode and feedback arrangement for a switching power converter
First Claim
1. A switching amplifier for receiving an input signal and for generating a differential output signal representative of the input signal comprising:
- a first pair of transistor switches for alternately raising and lowering a voltage potential of a first terminal of a first reactive element upon switching of the first pair of transistor switches;
a second pair of transistor switches for alternately raising and lowering a voltage potential of the first terminal of the first reactive element upon switching of the second pair of transistor switches;
a third pair of transistor switches for alternately raising and lowering a voltage potential of a first terminal of a second reactive element upon switching of the third pair of transistor switches;
a fourth pair of transistor switches for alternately raising and lowering a voltage potential of the first terminal of the second reactive element upon switching of the fourth pair of transistor switches;
a switch controller for controlling switching of the first, second, third and fourth pairs of transistor switches in accordance with the input signal for forming the differential output signal across a second terminal of the first reactive element and a second terminal of the second reactive element; and
a low signal level detector coupled to the second and fourth pair of transistor switches for disabling the second and fourth pair of transistor switches from switching upon detection of a low input signal level condition.
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Abstract
A low power mode and feedback arrangement for a switching power converter. Two or more main power switches, such as transistors, transfer energy from a supply to load by their opening and closing. When the load requires a relatively low power level, this condition is detected. In response, one or more of the transistor switches is disabled from switching and the reduced power requirements of the load are handled by the remaining one or more transistor switches. As a result, switching losses are reduced. This is because parasitic gate capacitance and on-resistance associated with the disabled switches no longer consume power from the power source. The invention provides significant efficiency advantages during periods when the load draws a low level of power. This is especially useful for battery-powered devices which may operate in a low power mode for extended periods of time, such as standby mode as in a portable telephone. This is because the prevention of power loss in may contribute considerably to operating time before battery re-charging is needed. However, when additional power is required, one or more previously disabled switches may be brought back into play to ensure that the power requirements of the load are met. In an audio amplifier having a H-bridge arrangement for providing a differential output signal, the invention also provides a feedback path from only one side of the load. This reduces distortion associated with open-ended operation.
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Citations
16 Claims
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1. A switching amplifier for receiving an input signal and for generating a differential output signal representative of the input signal comprising:
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a first pair of transistor switches for alternately raising and lowering a voltage potential of a first terminal of a first reactive element upon switching of the first pair of transistor switches;
a second pair of transistor switches for alternately raising and lowering a voltage potential of the first terminal of the first reactive element upon switching of the second pair of transistor switches;
a third pair of transistor switches for alternately raising and lowering a voltage potential of a first terminal of a second reactive element upon switching of the third pair of transistor switches;
a fourth pair of transistor switches for alternately raising and lowering a voltage potential of the first terminal of the second reactive element upon switching of the fourth pair of transistor switches;
a switch controller for controlling switching of the first, second, third and fourth pairs of transistor switches in accordance with the input signal for forming the differential output signal across a second terminal of the first reactive element and a second terminal of the second reactive element; and
a low signal level detector coupled to the second and fourth pair of transistor switches for disabling the second and fourth pair of transistor switches from switching upon detection of a low input signal level condition. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A switching amplifier for receiving an input signal and for generating a differential output signal representative of the input signal comprising:
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a first pair of transistor switches for alternately raising and lowering a voltage potential of a first terminal of a first reactive element upon switching of the first pair of transistor switches;
a second pair of transistor switches for alternately raising and lowering a voltage potential of a first terminal of a second reactive element upon switching of the second pair of transistor switches;
a switch controller for controlling switching of the first and second pairs of transistor switches in accordance with the input signal for forming the differential output signal across a second terminal of the first reactive element and a second terminal of the second reactive element; and
a feedback path from a terminal of the first reactive element to the switch controller for limiting the differential output signal. - View Dependent Claims (16)
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Specification