US 8,896,288 B2Granted

TRIAC dimmer detection

AssigneeMarvell World Trade Ltd.

InventorsJinho Choi, Hao Peng, Wanfeng Zhang, Tuyen Doan

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Abstract

Methods, circuits, and systems for determining the presence of a chopped input signal are disclosed. A digital signal generator can produce multiple digital signals when an alternating current (AC) signal input reaches multiple threshold voltages. The times at which the threshold voltages are reached can be determined by looking at the times at which the digital signals go high and low. The differences between the times at which the digital signals go high and low are used to determine if the AC signal input is a leading or trailing edge chopped signal. The AC input signal is a leading edge chopped signal when the difference between the times at which the digital signals go high is less than a predetermined time threshold, and is a trailing edge chopped signal when the difference between the times at which the digital signals go low is less than a predetermined time threshold.

Claims19

Dependent claims

A line voltage detection circuit comprising:

a first digital filter module configured to output a first high signal when an input signal reaches a first threshold voltage on a leading edge of the input signal and configured to output a first low signal when the input signal reaches the first threshold voltage on a trailing edge of the input signal;
a second digital filter module configured to output a second high signal when the input signal reaches a second threshold voltage on the leading edge of the input signal and configured to output a second low signal when the input signal reaches the second threshold voltage on the trailing edge of the input signal;
and
a third digital filter module configured to output a third high signal when the input signal reaches a third threshold voltage on the leading edge of the input signal and configured to output a third low signal when the input signal reaches the third threshold voltage on the trailing edge of the input signal,
wherein the line voltage detection circuit is configured to determine whether the input signal includes a leading edge chopped signal or a trailing edge chopped signal based on times at which the first threshold, the second threshold, and the third threshold are reached on the leading edge or the trailing edge.

2 more elements

A method of detecting a chopped input signal comprising:

setting a first threshold voltage;
setting a second threshold voltage;
receiving an input signal;
generating, using a first digital filter module, a first high digital output signal when the input signal reaches the first threshold voltage on a leading edge of the input signal and a first low digital output signal when the input signal reaches the first threshold voltage on a trailing edge of the input signal;
generating, using a second digital filter module, a second high digital output signal when the input signal reaches the second threshold voltage on the leading edge of the input signal and a second low digital output signal when the input signal reaches the second threshold voltage on the trailing edge of the input signal;
and
determining whether the input signal includes a leading edge chopped signal or a trailing edge chopped signal based on times at which the first threshold and the second threshold are reached on the leading edge or the trailing edge.

4 more elements

Dependencies are inferred from the claim text.

Facts

Application: 13/398,150Filed 16 Feb 2012 · us provisional application
Priority: 17 Feb 2011
Published: US 2012/0212258 A123 Aug 2012
Granted: 25 Nov 2014
Term ends: Not estimatedThe source records don’t support an estimate.

Classification9 codes

H02M 3/33523
With automatic control of the output voltage or current, e.g. flyback converters: with galvanic isolation between input and output of both the…
G01R 17/02
Measuring arrangements involving comparison with a reference value, e.g. bridge: arrangements in which the value to be measured is automatically…
G01R 19/0084
Arrangements for measuring currents or voltages or for indicating presence or sign thereof: measuring voltage only
H05B 45/10
Circuit arrangements for operating light-emitting diodes [LED]: controlling the intensity of the light