Direct current power supply circuit having automatic linear and switching modes
First Claim
1. A direct current power supply for converting an unregulated direct current input voltage into a regulated direct current output voltage comprising:
- (a) input and output terminals and a reference terminal;
(b) first means coupled to said output and reference terminals and responsive to a current demand below a predetermined current value to direct current to said output terminal in a linear mode;
(c) input control means coupled to said input terminal, said first means and said output terminal, said input control means responsive to current flow from said input terminal below said predetermined current value to direct substantially all of said input current to said first means and responsive to current flow from said input terminal above said predetermined current value to direct a variable portion of said input current directly to said output terminal;
(d) wherein said input control means comprises a semiconductor device having electron emitting, electron collecting and control electrodes and a resistor coupled between said input terminal and said control electrode, said electron emitting electrode being coupled to said input terminal and said electron collecting electrode being coupled to said output terminal.
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Abstract
A direct current power supply circuit converts an unregulated direct current input source such as an automobile battery to a regulated direct current output voltage for a device such as a mobile telephone requiring a fixed operating voltage. The circuit has an improved input to output voltage rating of less than two volts, enabling it to supply a load reliably with direct current power from an unregulated direct current source as low as ten volts. The circuit operates in a linear mode at low power levels and in a switching, pulse width modulated mode at higher output power levels. The circuit employs a three-terminal linear voltage regulator as a control element. It has input, output, and ground pins and is effective in response to current input through the input pin to maintain a predetermined, fixed voltage differential between the output and ground pins. In the example disclosed, the linear voltage regulator maintains a 5-volt differential between the output and ground pins. To provide fixed, stable 8-volt output, the circuit maintains a 3-volt potential at a reference junction connected to the ground pin. The linear voltage regulator seeks to maintain the 5-volt differential to thereby hold eight volts at the output pin. For high power requirements beyond the capacity of the linear voltage regulator, the circuit automatically varies the voltage at the reference junction to provide power pulses to the output of width and frequency required by the load.
32 Citations
12 Claims
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1. A direct current power supply for converting an unregulated direct current input voltage into a regulated direct current output voltage comprising:
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(a) input and output terminals and a reference terminal; (b) first means coupled to said output and reference terminals and responsive to a current demand below a predetermined current value to direct current to said output terminal in a linear mode; (c) input control means coupled to said input terminal, said first means and said output terminal, said input control means responsive to current flow from said input terminal below said predetermined current value to direct substantially all of said input current to said first means and responsive to current flow from said input terminal above said predetermined current value to direct a variable portion of said input current directly to said output terminal; (d) wherein said input control means comprises a semiconductor device having electron emitting, electron collecting and control electrodes and a resistor coupled between said input terminal and said control electrode, said electron emitting electrode being coupled to said input terminal and said electron collecting electrode being coupled to said output terminal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A direct current power supply for converting an unregulated direct current input voltage into a regulated direct current output voltage comprising:
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(a) input and output terminals and a reference terminal; (b) first means coupled to said output and reference terminals and responsive to a current demand below a predetermined current value to direct current to said output terminal in a linear mode; (c) input control means coupled to said input terminal, said first means and said output terminal, said input control means responsive to current flow from said input terminal below said predetermined current value to direct substantially all of said input current to said first means and responsive to current flow from said input terminal above said predetermined current value to direct a variable portion of said input current directly to said output terminal; (d) wherein said first means includes a reference voltage terminal and an output terminal, further including second means coupled between said reference voltage terminal and said reference terminal to maintain a predetermined reference voltage on said reference voltage terminal; (e) wherein said second means includes means responsive to said current flow from said input terminal above said predetermined current value to increase current flow from said first means to said output terminal, said input control means responsive to said current flow increase to increase said variable portion of said current, said first means responsive to said increase of current flow above a predetermined value to decrease current flow therethrough and in said input control means to substantially cut off said input current. - View Dependent Claims (10)
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11. A direct current power supply for converting an unregulated direct current input voltage into a regulated direct current output voltage comprising:
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(a) input and output terminals and a reference terminal; (b) first means coupled to said output and reference terminals and responsive to a current demand below a predetermined current value to direct current to said output terminal in a linear mode; (c) input control means coupled to said input terminal, said first means and said output terminal, said input control means responsive to current flow from said input terminal below said predetermined current value to direct substantially all of said input current to said first means and responsive to current flow from said input terminal above said predetermined current value to direct a variable portion of said input current directly to said output terminal; (d) wherein said first means includes a reference voltage terminal and an output terminal, further including second means coupled between said reference voltage terminal and said reference terminal to maintain a predetermined reference voltage on said reference voltage terminal; (e) wherein said second means includes a second semiconductor device having electron emitting, electron collecting and control electrodes, said electron emitting electrode of said second semiconductor device coupled to said reference voltage terminal of said first means and said electron collecting electrode of said second semiconductor device coupled to said reference terminal, a resistor coupled between said control electrode of said second semiconductor device and said output terminal of said first means, a zener diode coupled between said control electrode of said second semiconductor device and said reference terminal, the parallel combination of a resistor and a capacitor coupled between said control electrode of said second semiconductor device and said control electron collecting electrode of said first semiconductor device, a diode couple between said electron collecting electrode of said first semiconductor device and said reference terminal, a capacitor coupled between said output terminal of said first means and said reference terminal and an inductor coupled between said output terminal of said first means and said output terminal. - View Dependent Claims (12)
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Specification