Patent US10298125

DC-DC converter with active return flow lockout and method for operating a DC-DC converter
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US10298125

1. A DC-DC converter comprising: (4) (5)

a first coil terminal of an electrical coil connected with an input terminal of the DC-DC converter and a second coil terminal of the coil connected, first, via a rectification switch to an output terminal of the DC-DC converter and, second, via a control switch to a ground potential,

a control circuit connected to the rectification switch and the control switch, the control circuit configured to switch in successive switching cycles, respectively, in a regulating phase the rectification switch to be electrically blocking and the control switch to be electrically conducting, and in a rectifying phase to switch the control switch to be electrically blocking,

a measuring component configured to generate in the regulating phase a measurement signal which signals a current intensity of an electric coil current flowing through the coil,

a comparator circuit configured to compare the measurement signal with a predetermined threshold value,

wherein the control circuit is configured to switch, in the rectifying phase, the rectification switch to be electrically conducting, if the comparator circuit signals that the current intensity in the regulating phase was greater than the threshold value, and is further configured to keep the rectification switch to be electrically blocking and to cause the coil current to be conducted via a bypass diode to the output terminal if the current intensity in the regulating phase was continuously lower than the threshold value, and wherein the control circuit, in the regulating phase, with a coil current greater than the threshold value determines that in the subsequent rectifying phase there will not be a reversal of direction of the current flow, and with a current intensity less than the threshold value, when the current flow reverses its direction, causes the current to be conducted via the bypass diode instead of the rectification switch.

2. The DC-DC converter as claimed in claim 1, wherein the control circuit is configured to evaluate the comparator circuit with a predetermined time offset after the blocking of the control switch. (0)

3. The DC-DC converter as claimed in claim 1, wherein a current intensity of the coil current is unmonitored in the rectifying phase. (0)

4. The DC-DC converter as claimed in claim 1, wherein the rectification switch comprises a transistor comprising a body diode comprised in the bypass diode. (0)

5. The DC-DC converter as claimed in claim 1, wherein the measuring component comprises an electric resistor generating the measurement signal, the electric resistor preceding or following the control switch in such a manner that the coil current flows through the measuring component exclusively in the regulating phase. (0)

6. A method for operating a DC-DC converter as synchronous up converter, at a control circuit, in successive switching cycles, respectively in a regulating phase switching a rectification switch to be electrically blocking and a control switch to be electrically conducting, and in a rectifying phase switching the control switch to be electrically blocking, (0) (4)

at a comparator circuit, in the regulating phase, generating a measurement signal signaling a current intensity of an electric coil current flowing through an electric coil,

at a comparator circuit comparing the measurement signal with a predetermined threshold,

at the control circuit, in the rectifying phase, switching the rectification switch to be electrically conducting if the comparator circuit signals that the current intensity in the regulating phase was greater than the threshold value, and switching the rectification switch to be electrically blocking and, the coil current being conducted via a bypass diode to an output terminal if the comparator circuit signals that the current intensity in the regulating phase was continuously lower than the threshold value, and

at the control circuit, in the regulating phase, with a coil current greater than the threshold value, determining that in the subsequent rectifying phase a reversal of direction of the current flow will not occur and only with a lower current intensity than the threshold value, when the current flow reverses its direction, causing the current to be conducted via the bypass diode instead of the rectification switch.

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Patent US10298125

DC-DC converter with active return flow lockout and method for operating a DC-DC converter

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