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A control circuit and a lamp

A technology of control circuit and operational amplifier circuit, which is applied in the field of lighting, can solve the problems of reducing the output current and control signal of the step-down circuit, affecting the operation of the step-down circuit, and controlling LED errors, etc.

Active Publication Date: 2019-04-05
OPPLE LIGHTING
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] However, as the dimming depth increases, the operating frequency of the step-down circuit also increases. When the operating frequency is high enough, the delay of the driving signal generated by the control circuit will greatly affect the operation of the step-down circuit, and the inductor current will no longer It is a critical working mode, and the current peak value is no longer linearly proportional to the average value. At this time, the output current of the step-down circuit cannot be reduced proportionally to the control signal, thus limiting the dimming range of the circuit.
In addition, as the dimming depth increases, the reverse freewheeling current generated by the step-down circuit will also affect the actual average output current, resulting in a certain error when controlling the LED.

Method used

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Embodiment 2

[0100] see Figure 6 , the embodiment of the present invention also provides another control circuit, Figure 6 The control circuit in the illustrated embodiment is associated with Figure 5 The working principle of the control circuit shown is similar, the difference is that the dimming signal in this embodiment changes the DC dimming signal into a PWM dimming signal, and changes Figure 5 The shown adjustable resistor Rext is replaced by a second switch S, and the PWM dimming signal can control the second switch S to be turned on or off, thereby adjusting the inductor current reference voltage and further adjusting the inductor current reference value.

[0101] In this embodiment, if the second switch S is turned on, the inductor current reference voltage is zero, and if the second switch S is turned off, the inductor current reference voltage is the voltage of the internal reference signal Vref. The inductor current reference value is equivalent to the average value of Vd...

Embodiment 3

[0104] see Figure 7 , the embodiment of the present invention also provides another control circuit, Figure 7 The control circuit in the illustrated embodiment is associated with Figure 5 The working principle of the shown control circuit is similar, the difference is that the control circuit of this embodiment has a floating structure, and the floating drive / isolated drive U5 is omitted, that is, the floating drive or isolated drive is omitted, and the RS flip-flop U3 The output is directly connected to the gate of the first switch Q, the second switch S is replaced by a coupler U6, and the PWM dimming signal is coupled to the control circuit through the coupler U6.

[0105] In this embodiment, the coupler U6 uses an optocoupler. When the PWM dimming signal is at a high level, the optocoupler diode of the optocoupler is turned on, the optocoupler is turned on, and its output is short-circuited, and Vdim is at a low level. ; When the PWM dimming signal is at low level, th...

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Abstract

The invention provides a control circuit and a lamp. The control circuit includes a step-down circuit, an operational amplifier circuit, a dimming interface circuit, a clock signal generator, and a PWM logic circuit. A sampling unit for collecting and filtering inductor current is added to the step-down circuit. . The operational amplifier circuit receives the inductor current reference value and the filtered inductor current collected by the sampling unit, compares the filtered inductor current and the inductor current reference value, and outputs the comparison result as a first output signal. The PWM logic circuit controls the on-duty ratio of the first switch according to the control rule, so that the magnitude of the filter inductor current is equal to the reference value of the inductor current, thereby adjusting the current of the load connected to the filter inductor. The control circuit in the embodiment of the present invention abandons the indirect measurement method, and directly collects the current flowing through the filter inductor, so that the acquisition of the filter inductor current is more accurate and timely.

Description

technical field [0001] The invention relates to the technical field of lighting, in particular to a control circuit and a lamp. Background technique [0002] At present, in the field of lighting technology, the step-down circuit is more and more widely used in the driving circuit of the LED because of its low number of components and parts, high conversion efficiency, and suitable for converting high-voltage input to low-voltage output. [0003] However, as the dimming depth increases, the operating frequency of the step-down circuit also increases. When the operating frequency is high enough, the delay of the driving signal generated by the control circuit will greatly affect the operation of the step-down circuit, and the inductor current will no longer It is a critical working mode, and the current peak value is no longer linearly proportional to the average value. At this time, the output current of the step-down circuit cannot be reduced proportionally to the control si...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H05B33/08H05B44/00
CPCH05B45/00H05B45/37
Inventor 文威
Owner OPPLE LIGHTING