DC/DC converter and RS-232 interface circuit using the same
First Claim
1. A DC/DC converter, comprising:
- an input terminal supplied with an input voltage;
a first output terminal;
a reference terminal;
first, second, third, fourth and fifth nodes;
a first capacitor connected between said input terminal and said first node;
a second capacitor connected between said second and third nodes;
a third capacitor connected between said fourth and fifth nodes;
a first switch connected between said first and second nodes;
a second switch connected between said input terminal and said second node;
a third switch connected between said input terminal and said third node;
a fourth switch connected between said third node and said reference terminal;
a fifth switch connected between said first and fourth nodes;
a sixth switch connected between said second and fourth nodes;
a seventh switch connected between said second and fifth nodes;
an eighth switch connected between said fifth node and said reference terminal;
a control node supplied with a control signal which takes a first logic state in a first mode and a second logic state in a second mode;
means for operating in said first mode to control said first through eight switches such that a first voltage is produced at said first output terminal and in said second mode to control said first through eighth switches such that a second voltage is produced at said second output terminal, said first voltage assuming a first level which is two times as large as said input voltage and said second voltage assuming a second level which is three times as large as said input voltage means; and
means for transferring said first voltage to said first output terminal in said first mode and said second voltage to said first output terminal in said second mode.
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Accused Products
Abstract
There is provided a circuit for achieving a serial communication at the standard voltage defined in the RS-232 interface communication standard when the signal processing voltage of the host side circuit is 5 V and 3 V, for example, in which, when the DC input voltage Vin of the host side circuit is changed, this voltage level is detected to generate a stepped-up voltage having an appropriate step-up ratio by step-up circuits. This voltage level is detected to, regardless of the change of the power supply voltage, obtain the positive and negative DC output voltages Vdd, Vss matching with the RS-232 interface communication standard. To be specific, with the 5 V operation, a double stepped-up voltage within the DC/DC converter circuit and, during the 3 V operation, a three times stepped-up voltage are selectively generated to obtain the DC output voltage.
35 Citations
3 Claims
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1. A DC/DC converter, comprising:
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an input terminal supplied with an input voltage; a first output terminal; a reference terminal; first, second, third, fourth and fifth nodes; a first capacitor connected between said input terminal and said first node; a second capacitor connected between said second and third nodes; a third capacitor connected between said fourth and fifth nodes; a first switch connected between said first and second nodes; a second switch connected between said input terminal and said second node; a third switch connected between said input terminal and said third node; a fourth switch connected between said third node and said reference terminal; a fifth switch connected between said first and fourth nodes; a sixth switch connected between said second and fourth nodes; a seventh switch connected between said second and fifth nodes; an eighth switch connected between said fifth node and said reference terminal; a control node supplied with a control signal which takes a first logic state in a first mode and a second logic state in a second mode; means for operating in said first mode to control said first through eight switches such that a first voltage is produced at said first output terminal and in said second mode to control said first through eighth switches such that a second voltage is produced at said second output terminal, said first voltage assuming a first level which is two times as large as said input voltage and said second voltage assuming a second level which is three times as large as said input voltage means; and means for transferring said first voltage to said first output terminal in said first mode and said second voltage to said first output terminal in said second mode. - View Dependent Claims (2, 3)
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Specification