US 9,791,881 B2Granted

Self-driven synchronous rectification for a power converter

AssigneeInfineon Technologies Austria AG

InventorsGiuseppe Bernacchia, Olivier Guillemant

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Abstract

A power converter with an isolated topology may include a power transistor, a sense transistor, and a read-out circuit. The sense transistor may be arranged in a current mirror configuration with the power transistor such that the gate terminal of the sense transistor is coupled to the gate terminal of the power transistor and the first drain/source terminal of the sense transistor is coupled to the first drain/source terminal of the power transistor. The read-out circuit may be coupled to the second drain/source terminal of the power transistor and the second drain source/terminal of the sense transistor. The read-out circuit may be arranged to cause a voltage at the second drain/source terminal of the sense transistor to be substantially the same as a voltage at the second drain/source terminal of the power transistor.

Claims20

Dependent claims

A device, comprising a power converter having an isolated topology, including:

a power transistor including a gate terminal, a first drain/source terminal, and a second drain/source terminal;
a sense transistor including a gate terminal, a first drain/source terminal, and a second drain/source terminal, wherein:
the sense transistor is arranged in a current mirror configuration with the power transistor such that the gate terminal of the sense transistor is coupled to the gate terminal of the power transistor and the first drain/source terminal of the sense transistor is coupled to the first drain/source terminal of the power transistor, and
a current sense circuit is coupled to the second source/drain terminal of the sense transistor, wherein:
the current sense circuit includes an off comparator and a control block,
a threshold of the off comparator is a variable threshold, and
the control block adjusts the variable threshold based on at least one of device operating conditions, a device load, and a “slope gradient of the sense transistor current, wherein a turn-off time of the power transistor depends in part on the slope gradient of the sense transistor current”;
and
a read-out circuit is coupled to the second drain/source terminal of the power transistor and the second drain source/terminal of the sense transistor, wherein the read-out circuit is arranged to cause a voltage at the second drain/source terminal of the sense transistor to be substantially the same as a voltage at the second drain/source terminal of the power transistor.

6 more elements

Dependencies are inferred from the claim text.

Facts

Application: 14/338,191Filed 22 Jul 2014
Published: US 2016/0028319 A128 Jan 2016
Granted: 17 Oct 2017
Term ends: Not estimatedThe source records don’t support an estimate.

Classification12 codes

G05F 3/24
Using diode- transistor combinations: wherein the transistors are of the field-effect type only
G05F 3/10
Wherein the variable is DC: using uncontrolled devices with non-linear characteristics
H02M 3/33576
Having several active switching elements: having at least one active switching element at the secondary side of an isolation transformer
H02M 3/33592
Having at least one active switching element at the secondary side of an isolation transformer: having a synchronous rectifier circuit or a…