Isolated DC-DC converter
First Claim
1. An isolated DC-DC converter, comprising:
- an input node configured to have an input voltage;
a transformer including a primary side having first and second terminals and a primary ground terminal;
first and second high-side switches, the first high-side switch coupled between the first terminal and the input node, and the second high-side switch coupled between the second terminal and the input node;
first and second voltage limiters;
a first low-side switch coupled between the first terminal and the primary ground terminal, the first low-side switch having a gate coupled through the first voltage limiter to the second terminal;
a second low-side switch coupled between the second terminal and the primary ground terminal, the second low-side switch having a gate coupled through the second voltage limiter to the first terminal; and
a switch controller configured to;
close the first high-side switch to cause a first voltage across the first high side switch to be zero;
during a first phase, open the first high-side switch, while keeping the second high-side switch open, to enable a current through the primary side to reduce a second voltage across the second high-side switch to zero by charging the second terminal to the input voltage and discharging the first terminal;
close the second high-side switch when the second voltage is zero; and
during a second phase, open the second high-side switch, while keeping the first high-side switch open, to enable the current through the primary side to reduce the first voltage to zero by charging the first terminal to the input voltage and discharging the second terminal.
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Accused Products
Abstract
In described examples, an isolated DC-DC converter includes an input node for receiving an input voltage, and a transformer including a primary side having first and second terminals and a ground. First and second high-side switches are coupled between the input node and the first and second terminals, respectively. A first low-side switch is coupled between the first terminal and the ground, and through a first voltage limiter to be activated by a voltage at the second terminal. A second low-side switch is coupled between the second terminal and the ground, and through a second voltage limiter to be activated by a voltage at the first terminal. A switch controller controls the high-side switches so that voltages across the high-side switches are alternatingly zero, using a current through the primary side to alternatingly charge one terminal to an input voltage and discharge the other terminal to a ground voltage.
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Citations
18 Claims
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1. An isolated DC-DC converter, comprising:
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an input node configured to have an input voltage; a transformer including a primary side having first and second terminals and a primary ground terminal; first and second high-side switches, the first high-side switch coupled between the first terminal and the input node, and the second high-side switch coupled between the second terminal and the input node; first and second voltage limiters; a first low-side switch coupled between the first terminal and the primary ground terminal, the first low-side switch having a gate coupled through the first voltage limiter to the second terminal; a second low-side switch coupled between the second terminal and the primary ground terminal, the second low-side switch having a gate coupled through the second voltage limiter to the first terminal; and a switch controller configured to;
close the first high-side switch to cause a first voltage across the first high side switch to be zero;
during a first phase, open the first high-side switch, while keeping the second high-side switch open, to enable a current through the primary side to reduce a second voltage across the second high-side switch to zero by charging the second terminal to the input voltage and discharging the first terminal;
close the second high-side switch when the second voltage is zero; and
during a second phase, open the second high-side switch, while keeping the first high-side switch open, to enable the current through the primary side to reduce the first voltage to zero by charging the first terminal to the input voltage and discharging the second terminal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method of driving an isolated DC-DC converter, the method comprising:
- responsive to a voltage at a first terminal of a primary side of a transformer reaching an input voltage of an input node, causing a first high-side switch to connect the first terminal to the input node, and such that, while the first high-side switch connects the first terminal to the input node, the voltage at the first terminal, which is coupled to a gate of a first low-side switch, causes the first low-side switch to connect a second terminal of the primary side of the transformer to a primary ground terminal;
causing the first high-side switch to disconnect the first terminal from the input node, while keeping the second terminal disconnected from the input node, to enable a current through the primary side to charge the second terminal to the input voltage, while discharging the first terminal;
responsive to a voltage at the second terminal reaching the input voltage, causing a second high-side switch to connect the second terminal to the input node, such that while the second high-side switch connects the second terminal to the input node, the voltage at the second terminal, which is coupled to a gate of a second low-side switch, causes the second low-side switch to connect the first terminal to the primary ground terminal; and
causing the second high-side switch to disconnect the second terminal from the input node, while keeping the first terminal disconnected from the input node, to enable the current through the primary side to charge the first terminal to the input voltage, while discharging the second terminal. - View Dependent Claims (11, 12)
- responsive to a voltage at a first terminal of a primary side of a transformer reaching an input voltage of an input node, causing a first high-side switch to connect the first terminal to the input node, and such that, while the first high-side switch connects the first terminal to the input node, the voltage at the first terminal, which is coupled to a gate of a first low-side switch, causes the first low-side switch to connect a second terminal of the primary side of the transformer to a primary ground terminal;
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13. An isolated DC-DC converter, comprising:
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an input node configured to have an input voltage; an output node configured to have an output voltage; a transformer including;
a primary side having first and second primary terminals and a primary ground terminal, and a secondary side having first and second secondary terminals and a secondary ground terminal;first and second primary high-side transistors, the first primary high-side transistor coupled between the first primary terminal and the input node, and the second primary high-side transistor coupled between the second primary terminal and the input node; first and second primary voltage limiters; a first primary low-side transistor coupled between the first primary terminal and the primary ground terminal, the first primary low-side transistor having a gate coupled through the first primary voltage limiter to the second primary terminal; a second primary low-side transistor coupled between the second primary terminal and the primary ground terminal, the second primary low-side transistor having a gate coupled through the second primary voltage limiter to the first primary terminal; first and second secondary high-side transistors, the first secondary high-side transistor coupled between the first secondary terminal and the output node, and the second secondary high-side transistor coupled between the second secondary terminal and the output node; first and second secondary voltage limiters; a first secondary low-side transistor coupled between the first secondary terminal and the secondary ground terminal, the first secondary low-side transistor having a gate coupled through the first secondary voltage limiter to the second secondary terminal; a second secondary low-side transistor coupled between the second secondary terminal and the secondary ground terminal, the second secondary low-side transistor having a gate coupled through the second secondary voltage limiter to the first secondary terminal; and at least one switch controller configured to;
close the first primary high-side transistor to cause a first voltage across the first primary high-side transistor to be zero;
during a first phase, open the first primary high-side transistor, while keeping the second primary high-side transistor open, to enable a current through the primary side to reduce a second voltage across the second primary high-side transistor to zero by charging the second primary terminal to the input voltage and discharging the first primary terminal;
close the second primary high-side transistor when the second voltage is zero; and
during a second phase, open the second primary high-side transistor, while keeping the first primary high-side transistor open, to enable the current through the primary side to reduce the first voltage to zero by charging the first primary terminal to the input voltage and discharging the second primary terminal. - View Dependent Claims (14, 15, 16, 17, 18)
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Specification