Shutdown circuit for a switching regulator in a remote controlled television receiver
First Claim
1. A switching power supply with disabling circuitry, comprising:
- a source of input voltage;
a power supply inductance coupled to said input voltage source;
a load circuit coupled to said inductance;
a power switch coupled to said inductance;
a regulator control circuit coupled to said power switch for producing the switching thereof to transfer energy from said input voltage source to said load circuit, said regulator control circuit being responsive to control voltages for varying the switching duty-cycle of said power switch to control the transfer of energy to said load circuit;
means for developing a first one of said control voltages representative of variations in an energy level of said load circuit to control said duty-cycle in a manner that regulates said energy level;
a disabling circuit coupled to said regulator control circuit and responsive to the voltage at a disabling control terminal for developing a second one of said control voltages that changes said duty-cycle in a manner that disables the normal transfer of energy to said load circuit, said second one control voltage being generated when the disabling control terminal is biased to a voltage that is beyond a given value;
a disabling switch coupled to said disabling control terminal;
a comparator coupled to said disabling switch;
a disabling input terminal coupled to an input terminal of said comparator and to said disabling control terminal;
a first signal generator responsive to a first condition requiring the disablement of said power supply for developing at said disabling input terminal a first bias voltage that exceeds a first value in a first direction in order to bias said disabling control terminal to a voltage that is beyond said given value; and
a second signal generator responsive to a second condition requiring the disablement of said power supply for developing at said disabling input terminal a second bias voltage that exceeds a second value in the direction opposite that of said first direction in order to bias the input terminal of said comparator beyond a first trigger level voltage in a first direction to activate said comparator, said disabling switch changing conductive states when said comparator is activated for biasing said disabling control terminal to a voltage that is beyond said given value.
2 Assignments
0 Petitions
Accused Products
Abstract
In a switching regulator power supply, the primary winding of a switching transformer is coupled to a source of input voltage and to a power switch. Secondary supply voltages for a load circuit such as a television receiver are obtained from a secondary winding of the transformer. A regulator control circuit develops a pulse width modulated signal that is used to control the duty-cycle of the power switch for regulating the supply voltages. A disabling circuit is coupled to the regulator control circuit and is responsive to a low bias voltage at a disabling control terminal to change the duty cycle of the power switch in a manner that disables the normal transfer of energy to the load circuit. A disabling input terminal is coupled to an input terminal of a comparator and to the disabling control terminal. The comparator output is coupled to a disabling switch having an output coupled to the disabling control terminal. A first signal generator is responsive to a first condition requiring the disabling of the power supply and develops at the disabling input terminal a first bias voltage that is low enough to, in turn, bias low the disabling control terminal to initiate the disabling of the power supply. A second signal generator is responsive to a second condition requiring the disabling of the power supply and develops a second bias voltage that is higher than the first bias voltage and is high enough to activate the comparator. When the comparator is activated, the disabling switch turns on to bias low the disabling control terminal to initiate the disabling of the power supply.
30 Citations
8 Claims
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1. A switching power supply with disabling circuitry, comprising:
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a source of input voltage; a power supply inductance coupled to said input voltage source; a load circuit coupled to said inductance; a power switch coupled to said inductance; a regulator control circuit coupled to said power switch for producing the switching thereof to transfer energy from said input voltage source to said load circuit, said regulator control circuit being responsive to control voltages for varying the switching duty-cycle of said power switch to control the transfer of energy to said load circuit; means for developing a first one of said control voltages representative of variations in an energy level of said load circuit to control said duty-cycle in a manner that regulates said energy level; a disabling circuit coupled to said regulator control circuit and responsive to the voltage at a disabling control terminal for developing a second one of said control voltages that changes said duty-cycle in a manner that disables the normal transfer of energy to said load circuit, said second one control voltage being generated when the disabling control terminal is biased to a voltage that is beyond a given value; a disabling switch coupled to said disabling control terminal; a comparator coupled to said disabling switch; a disabling input terminal coupled to an input terminal of said comparator and to said disabling control terminal; a first signal generator responsive to a first condition requiring the disablement of said power supply for developing at said disabling input terminal a first bias voltage that exceeds a first value in a first direction in order to bias said disabling control terminal to a voltage that is beyond said given value; and a second signal generator responsive to a second condition requiring the disablement of said power supply for developing at said disabling input terminal a second bias voltage that exceeds a second value in the direction opposite that of said first direction in order to bias the input terminal of said comparator beyond a first trigger level voltage in a first direction to activate said comparator, said disabling switch changing conductive states when said comparator is activated for biasing said disabling control terminal to a voltage that is beyond said given value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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Specification