Constant voltage power supply circuit
a power supply circuit and constant voltage technology, applied in power conversion systems, frequency selective two-port networks, instruments, etc., can solve the problems of power supply efficiency degradation, power supply efficiency decline, capacitor ca cannot be integrated and externally attached capacitors, etc., to achieve high voltage efficiency
Inactive Publication Date: 2008-05-29
RICOH KK
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AI Technical Summary
Benefits of technology
The solution effectively cancels ripple voltage at the output terminal, reducing voltage drop and improving power supply efficiency while allowing for integration of the constant voltage power supply unit and ripple removing circuit into a single IC, enhancing overall performance.
Problems solved by technology
As a result, the voltage drop across the NPN transistor Qa is further increased, and therefore the power supply efficiency is degraded.
On the other hand, if the capacitance of the capacitor Ca is made large, the large size of the capacitance Ca makes it impossible to integrate the capacitor Ca and the capacitor Ca has to be externally attached.
When an output current of the series regulator 106 is large, the voltage drop thereof also becomes large, resulting in degradation of the power supply efficiency.
Method used
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Embodiment Construction
[0036]In the following, an embodiment of the present invention is described with reference to the accompanying drawings.
[0037]The embodiment of the present invention is explained with reference to FIG. 1 through FIG. 4. FIG. 1 is a block diagram of a constant voltage power supply circuit 1 according to the embodiment of the present invention.
[0038]The constant voltage power supply circuit 1 comprises a constant voltage power supply unit 2 that receives a power supply voltage Vdd and is ideally desired to generate and output a predetermined constant voltage V1, and a ripple removing circuit unit 3 connected between an output end OUT1 of the constant voltage power supply unit 2 and an output terminal OUT of the constant voltage power supply circuit 1.
[0039]The ripple removing circuit unit 3 comprises a resistor R1 connected between the output end OUT1 of the constant voltage power supply unit 2 and the output terminal OUT, a ripple voltage detection circuit 5 for detecting a ripple vo...
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A disclosed constant voltage power supply circuit (1) has an input terminal (Vdd), an output terminal (Vout), a constant voltage power supply unit (2) that generates a constant voltage (Vo1) with a ripple voltage (Vri), and a ripple removing circuit unit (3) for removing the ripple voltage so that a constant voltage (V1) without the ripple voltage is output at the output terminal (OUT). The ripple removing circuit unit comprises a resistor (R1) connected between the constant voltage power supply unit and the output terminal; a ripple voltage detection circuit unit (5) for detecting the ripple voltage and outputting a signal depending on the detected ripple voltage; and a current circuit unit (6, 7) for receiving the signal from the ripple voltage detection circuit unit and supplying a current (io1) to the output terminal or absorbing a current (io2) from the resistor in response to the received signal, so as to cancel the ripple voltage at the output terminal.
Description
TECHNICAL FIELD[0001]The present invention generally relates to a constant voltage power supply circuit, and especially relates to such a constant voltage power supply circuit that can cancel a ripple voltage while maintaining high voltage efficiency.BACKGROUND ART[0002]In constant voltage power supply circuits including a constant voltage power supply unit, a ripple voltage is inherently generated in an output voltage of the constant voltage power supply unit due to a variety of causes. A ripple filter is known for removing such ripple voltage as disclosed in Patent Reference No. 1.[0003]FIG. 5 shows a conventional constant voltage power supply circuit 100 using a ripple filter.[0004]The constant voltage power supply circuit 100 comprises a constant voltage power supply unit 101 that generates and outputs a predetermined constant voltage, and a ripple filter 102 connected between an output end A and an output terminal OUTa.[0005]The ripple filter 102 comprises an NPN transistor Qa,...
Claims
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IPC IPC(8): G05F5/08
CPCH02M1/12H02J1/02H03H11/04
InventorNISHIDA, JUNJI
OwnerRICOH KK