Voltage balancing circuit
AssigneeSamsung Electronics Co., Ltd.
InventorsYong-Ho Kim, Young-sik Lee
Life of this patent
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Abstract
A voltage balancing circuit and methods are disclosed for providing power from a single DC power supply to a circuit, such as an integrated circuit, that presents both a positive load and a negative load to the power supply, while ensuring that the positive load voltage and the negative load voltage remains substantially equal in magnitude, notwithstanding variations in the magnitudes of the loads. A voltage divider circuit provides a reference voltage equal to one-half of the total power supply voltage. Capacitors are provided across each of the positive and negative loads.
Claims11
A voltage balancing circuit for providing power to a positive load and to a negative load from a single power supply having first and second power supply terminals, the power supply providing a supply voltage across the terminals, the positive load and the negative load being coupled in series across the power supply terminals, and having a common node intermediate the positive load and the negative load connected to ground, the voltage balancing circuit comprising:
- reference voltage means for providing a reference voltage equal to one-half of the power supply voltage;
- first and second capacitors disposed in series across the power supply terminals, the first and second capacitors having equal capacitances, and having a common capacitor node intermediate the first and second capacitors coupled to ground;
- means for comparing the common capacitor node voltage to the reference voltage and providing an error signal responsive to a difference between the common capacitor node voltage and the reference voltage, said comparing means comprising an operational amplifier having a first input terminal coupled to the common capacitor node, a second input terminal coupled to the reference voltage and an output terminal coupled to the amplifier means to provide the error signal;
- amplifier means responsive to the error signal for driving the common capacitor node ground voltage toward the reference voltage so as to reduce the error signal to a minimum when the ground voltage is equal to the reference voltage, thereby ensuring that a first voltage applied to the positive load and a second voltage applied to the negative load remain substantially equal in magnitude, said amplifier means comprising a transistor arranged to control current flow between the common capacitor ground node and a selected one of the power supply terminals, the transistor having a base terminal coupled to the operational amplifier output terminal for controlling the transistor responsive to the error signal;
- and
- a voltage clamping means for clamping the first and second voltages so as to not exceed a predetermined voltage, said voltage clamping means comprising first and second zener diodes arranged in parallel to the first and second capacitors, respectively.
A voltage balancing circuit for providing power from a single DC power supply to an integrated circuit that presents both a positive load and to a negative load to the power supply, the power supply having first and second power supply terminals, and providing a substantially constant supply voltage across the terminals, the integrated circuit being connected to the power supply such that the positive load and the negative load are coupled in series across the power supply terminals, a common node intermediate the positive load and the negative load being connected to ground, the voltage balancing circuit comprising:
- a resistive voltage divider circuit connected across the power supply terminals to provide a reference voltage equal to one-half of the total power supply voltage;
- first and second capacitors disposed in series across the power supply terminals, the first and second capacitors having equal capacitances, and a common capacitor node intermediate the first and second capacitors being coupled to a ground node, whereby the first and second capacitors are connected in parallel with the positive load and the negative load, respectively;
- an operational amplifier arranged for comparing the ground node voltage to the reference voltage and providing an error signal responsive to a difference between the ground node voltage and the reference voltage;
- a resistor having one side connected to one of said first and second power supply terminals;
- and
- a transistor having a first side connected to the ground node and a second side connected to the other side of said resistor, the transistor further having a base terminal coupled to receive the error signal so that the transistor drives the ground node voltage toward the reference voltage, thereby ensuring that a first voltage applied to the positive load and a second voltage applied to the negative load remain substantially equal in magnitude and the sum of the magnitudes of the first and second voltages remains substantially constant.
A voltage balancing circuit for providing power from a single DC power supply to an integrated circuit that presents both a positive load and to a negative load to the power supply, the power supply having first and second power supply terminals, and providing a supply voltage across the terminals, the integrated circuit being connected to the power supply such that the positive load and the negative load are coupled in series across the power supply terminals, a common node intermediate the positive load and the negative load being connected to ground, the voltage balancing circuit comprising:
- a resistive voltage divider circuit connected across the power supply terminals to provide a reference voltage equal to one-half of the total power supply voltage;
- first and second capacitors disposed in series across the power supply terminals, the first and second capacitors having equal capacitances, and a common capacitor node intermediate the first and second capacitors being coupled to a ground node, whereby the first and second capacitors are connected in parallel with the positive load and the negative load, respectively;
- an operational amplifier arranged for comparing the ground node voltage to the reference voltage and providing an error signal responsive to a difference between the ground node voltage and the reference voltage;
- a transistor coupled between the ground node and one of said power supply terminals, the transistor further having a base terminal coupled to receive the error signal so that the transistor drives the ground node voltage toward the reference voltage, thereby ensuring that a first voltage applied to the positive load and a second voltage applied to the negative load remain substantially equal in magnitude;
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- first and second zener diodes arranged in parallel to the first and second capacitors, respectively, for clamping the first and second voltages, respectively, to a predetermined zener diode voltage.
Dependencies are inferred from the claim text.