Open-circuit protection circuit of constant current driving circuit for light emitting diodes
First Claim
1. An open-circuit protection circuit of a constant current driving circuit for light emitting diodes, comprising a transformer which comprises at least one secondary winding connected to at least two load branches, each of the load branches having a same structure;
- wherein;
each of the load branches and the secondary winding form a rectification loop, and the secondary winding has a tap end which divides the secondary winding into two secondary sub-windings;
the circuit further comprises a current sharing transformer provided in two adjacent load branches; and
each of the load branches is connected to an open-circuit protection module which comprises a detection control unit and a processing unit, wherein;
the detection control unit is configured to output a control signal to the processing unit when the detection control unit detects that an output voltage of the load branch or a voltage proportional to the output voltage is not less than a corresponding preset threshold; and
the processing unit is configured to short the secondary sub-winding in the corresponding load branch and a current sharing winding of the current sharing transformer connected in series with the secondary sub-winding once the control signal is received.
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Accused Products
Abstract
A open-circuit protection circuit of a constant current driving circuit for light emitting diodes is disclosed, which includes that: a transformer (Ta1), which has at least one secondary winding (WT1), is connected to at least two load branches (A1, A2); a commutating loop is composed of each load branches (A1, A2) and one secondary winding (WT1), wherein the secondary winding (WT1) has tap ends; a current sharing transformer (T1) is set in two neighbor load branch (A1, A2); each load branch (A1, A2) is separately connected to one open-circuit protection module (10). The open circuit protection module (10) includes: a detection control unit (101), used for outputting a control signal to a processing unit (102) when the detection control unit detects that the output voltages of each load branch (A1, A2) or the voltages proportionate to the output voltages are not less than a corresponding preset threshold; the processing unit (102), used for shorting one secondary sub winding (WT11, WT12) in the corresponding load branch (A1, A2) and a sharing current winding (W1) of the current sharing transformer (T1) in series with the secondary sub winding (WT11, WT12) when receiving the control signal. With the embodiments of the present invention, the cost and the bulk of the current sharing transformer (T1) can be reduced.
6 Citations
14 Claims
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1. An open-circuit protection circuit of a constant current driving circuit for light emitting diodes, comprising a transformer which comprises at least one secondary winding connected to at least two load branches, each of the load branches having a same structure;
- wherein;
each of the load branches and the secondary winding form a rectification loop, and the secondary winding has a tap end which divides the secondary winding into two secondary sub-windings; the circuit further comprises a current sharing transformer provided in two adjacent load branches; and each of the load branches is connected to an open-circuit protection module which comprises a detection control unit and a processing unit, wherein; the detection control unit is configured to output a control signal to the processing unit when the detection control unit detects that an output voltage of the load branch or a voltage proportional to the output voltage is not less than a corresponding preset threshold; and the processing unit is configured to short the secondary sub-winding in the corresponding load branch and a current sharing winding of the current sharing transformer connected in series with the secondary sub-winding once the control signal is received. - View Dependent Claims (2, 3, 4, 5, 6, 7)
- wherein;
-
8. An open-circuit protection circuit of a constant current driving circuit for light emitting diodes, comprising a transformer which comprises at least one secondary winding connected to at least two load branches, each of the load branches having a same structure;
- wherein;
each of the load branches and the secondary winding form a rectification loop, and the secondary winding has a tap end which divides the secondary winding into two secondary sub-windings; the circuit further comprises a current sharing transformer connected in series in each of the load branches, wherein a primary current sharing winding of each current sharing transformer is respectively connected to a secondary sub-winding of a secondary winding corresponding to each of the load branches, and secondary current sharing windings of the current sharing transformers are connected in series sequentially; and each of the load branches is connected to an open-circuit protection module which comprises a detection control unit and a processing unit, wherein; the detection control unit is configured to output a control signal to the processing unit when the detection control unit detects that an output voltage of the load branch or a voltage proportional to the output voltage is not less than a corresponding preset threshold; and the processing unit is configured to perform shorting between the tab end of the secondary winding and one terminal of the primary current sharing winding of the current sharing transformer which is not connected to the secondary winding once the control signal is received. - View Dependent Claims (9, 10, 11, 12, 13, 14)
- wherein;
Specification