Chopper type DC-DC converter

A DC-DC converter having an output terminal to be connected to a load, for producing a desired output voltage at the output terminal based on the voltage from a DC power supply, the converter comprising:

• an output capacitor having a first electrode connected to the output terminal and a second electrode;
• charge/discharge regulation means for controlling connection between the DC power supply and said output capacitor to permit said output capacitor to be charged or discharged, wherein a potential of said first electrode of said output capacitor is set to the desired output voltage different from a potential of the DC power supply;
• first detecting means for detecting a change in output voltage at the output terminal;
• second detecting means for detecting a variable load current flowing into the DC-DC converter from the load via the output terminal;
• and
• voltage control means for controlling a potential of said second electrode of said output capacitor in such a manner as to nullify a variation in the output voltage, based on a result of detection of said output voltage by said first detecting means and on a result of detection of said load current by said second detecting means, wherein said second detecting means includes:
• a capacitor to be charged by a first current which is derived from said load current and is supplied thereto via a resistor;
• a transistor for allowing a second current derived from said load current to escape to ground, therein reducing said first current flowing through said resistor;
• and
• a comparator for comparing a charged voltage of said capacitor with a reference voltage provided thereto and for outputting a detection signal.

A DC-DC converter having an output terminal to be connected to a load, for producing a desired output voltage at the output terminal based on the voltage from a DC power supply, the converter comprising:

• an output capacitor having a first electrode connected to the output terminal and a second electrode;
• charge/discharge regulation means for controlling connection between the DC power supply and said output capacitor to permit said output capacitor to be charged or discharged, wherein a potential of said first electrode of said output capacitor is set to the desired output voltage different from a potential of the DC power supply;
• first detecting means for detecting a change in output voltage at the output terminal;
• second detecting means for detecting a variable load current flowing into the DC-DC converter from the load via the output terminal;
• and
• voltage control means for controlling a potential of said second electrode of said output capacitor in such a manner as to nullify a variation in the output voltage, based on a result of detection of said output voltage by said first detecting means and on a result of detection of said load current by said second detecting means,
• wherein said charge/discharge regulation means includes a switching transistor for controlling connection between said DC power supply and said output capacitor;
• and
• wherein said first detecting means includes:
• a voltage-dividing resistor for dividing said output voltage;
• an operation amplifier for receiving the divided voltage by said voltage-dividing resistor and for outputting a voltage whose level is relative to a level of said divided voltage;
• and
• a transistor for allowing a current flow therethrough in proportion to said output voltage from said operational amplifier,
• wherein said switching transistor is controlled based on said current flowing through said transistor.

A DC-DC converter having an output terminal to be connected to a load, for producing a desired output voltage at the output terminal based on the voltage from a DC power supply, the converter comprising:

• an output capacitor having a first electrode connected to the output terminal and a second electrode;
• charge/discharge regulation means for controlling connection between the DC power supply, and said output capacitor to permit said output capacitor to be charged or discharged, wherein a potential of said first electrode of said output capacitor is set to the desired output voltage different from a potential of the DC power supply;
• first detecting means for detecting a change in output voltage at the output terminal;
• second detecting means for detecting a variable load current flowing into the DC-DC converter from the load via the output terminal;
• and
• voltage control means for controlling a potential of said second electrode of said output capacitor in such a manner as to nullify a variation in the output voltage, based on a result of detection of said output voltage by said first detecting means and on a result of detection of said load current by said second detecting means, wherein said second detecting means includes:
• a voltage-dividing resistor for dividing said output voltage;
• an operational amplifier for receiving the divided voltage by said voltage-dividing resistor and for outputting a voltage whose level is relative to a level of said divided voltage;
• and
• a transistor controlled based on said output voltage from said operational amplifier, for allowing a current, derived from said load current, to escape to ground.

A DC-DC converter having an output terminal to be connected to a load, for producing a desired output voltage at the output terminal based on the voltage from a DC power supply, the converter comprising:

• an output capacitor having a first electrode connected to the output terminal and a second electrode;
• charge/discharge regulation means for controlling connection between the DC power supply and said output capacitor to permit said output capacitor to be charged or discharged, wherein a potential of said first electrode of said output capacitor is set to the desired output voltage different from a potential of the DC power supply;
• first detecting means for detecting a change in output voltage at the output terminal;
• second detecting means for detecting a variable load current flowing into the DC-DC converter from the load via the output terminal;
• and
• voltage control means for controlling a potential of said second electrode of said output capacitor in such a manner as to nullify a variation in the output voltage, based on a result of detection of said output voltage by said first detecting means and on a result of detection of said load current by said second detecting means, wherein said voltage control means includes:
• a current mirror circuit;
• a first transistor for permitting a current from said current mirror circuit to flow to ground, based on detection signals from said first detecting means and said second detecting means;
• second transistors for permitting said current from said current mirror circuit to flow to said ground, based on a received rectangular wave signal;
• and
• a third transistor for producing a signal for controlling charge/discharge of said output capacitor by said charge/discharge regulation means, based on ON/OFF functions of said first and second transistors.