Isolated synchronous rectifying DC/DC converter
AssigneeRohm Co., Ltd.
InventorHiroki Kikuchi
Life of this patent
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Abstract
A synchronous rectification controller includes: a drain terminal connected to a drain of a synchronous rectification transistor; a first comparator configured to compare a drain voltage of the drain terminal with a first threshold voltage; a second comparator configured to compare the drain voltage of the drain terminal with a second threshold voltage; a flip-flop to which an ON signal output from the first comparator and an OFF signal output from the second comparator are input; a driver configured to output a gate signal to the synchronous rectification transistor based on an output signal of the flip-flop; and a threshold adjusting part configured to adjust the second threshold voltage based on the drain voltage.
Claims16
An isolated synchronous rectifying DC/DC converter configured as an LLC converter, the DC/DC converter comprising:
- a synchronous rectification transistor disposed on a secondary side of the DC/DC converter;
- and
- a synchronous rectification controller configured to control driving of the synchronous rectification transistor,
- wherein the synchronous rectification controller includes:
- a drain terminal connected to a drain of the synchronous rectification transistor;
- a first comparator configured to compare a drain voltage of the drain terminal with a first threshold voltage;
- a second comparator configured to compare the drain voltage of the drain terminal with a second threshold voltage;
- a flip-flop to which an ON signal output from the first comparator and an OFF signal output from the second comparator are input;
- a driver configured to output a gate signal to the synchronous rectification transistor based on an output signal of the flip-flop;
- and
- a threshold adjusting part configured to adjust the second threshold voltage based on the drain voltage, and
- wherein the threshold adjusting part includes a sample hold circuit configured to sample and hold the drain voltage, and is configured to adjust the second threshold voltage based on a sampling voltage output from the sample hold circuit.
An isolated synchronous rectifying DC/DC converter configured as an LLC converter, the DC/DC converter comprising:
- a synchronous rectification transistor disposed on a secondary side of the DC/DC converter;
- and
- a synchronous rectification controller configured to control driving of the synchronous rectification transistor,
- wherein the synchronous rectification controller includes:
- a drain terminal connected to a drain of the synchronous rectification transistor;
- a first comparator configured to compare a drain voltage of the drain terminal with a first threshold voltage;
- a second comparator configured to compare the drain voltage of the drain terminal with a second threshold voltage;
- a flip-flop to which an ON signal output from the first comparator and an OFF signal output from the second comparator are input;
- a driver configured to output a gate signal to the synchronous rectification transistor based on an output signal of the flip-flop;
- and
- a threshold adjusting part configured to adjust the second threshold voltage based on the drain voltage, and
- wherein the threshold adjusting part is disposed between the drain terminal and the second comparator.
An isolated synchronous rectifying DC/DC converter configured as an LLC converter, the DC/DC converter comprising:
- first and second synchronous rectification transistors disposed on a secondary side of the DC/DC converter;
- and
- a synchronous rectification controller configured to control driving of the first and second synchronous rectification transistors,
- wherein the synchronous rectification controller includes:
- first and second drain terminals connected to drains of the first and second synchronous rectification transistors, respectively;
- a first comparator configured to compare the drain voltages of the first and second drain terminals with a first threshold voltage;
- a second comparator configured to compare the drain voltages of the first and second drain terminals with a second threshold voltage;
- a flip-flop to which an ON signal output from the first comparator and an OFF signal output from the second comparator are input;
- first and second drivers configured to output gate signals to the first and second synchronous rectification transistors, respectively, based on an output signal of the flip-flop;
- a selector having an output terminal connected to the first and second comparators and an input terminal to which the output signal of the flip-flop is input, and configured to perform:
- a first operation of switching between conduction of a path from the first drain terminal to the output terminal and conduction of a path from the second drain terminal to the output terminal;
- and
- a second operation of switching between conduction of a path from the input terminal to the first driver and conduction of a path from the input terminal to the second driver;
- and
- a threshold adjusting part configured to adjust the second threshold voltage based on the drain voltages.
Dependencies are inferred from the claim text.