Light-emitting diode lighting device
An LED lighting device includes at least two luminescent devices, two current sensing elements, and two current regulators. The first and second luminescent device are driven by a rectified AC voltage for providing light according to first current and second current, respectively. The first current sensing element provides a first feedback voltage associated with the first current and the second current sensing element provides a second feedback voltage associated with the second current. The first current regulator provides a first regulating current setting according to the first feedback voltage and a line voltage detection voltage associated with the rectified AC voltage, wherein the waveform of the first regulating current setting follows the waveform of the rectified AC voltage. The second current controller is coupled in parallel to the second luminescent device and provides a constant second regulating current setting according to the second feedback voltage.
1. A light-emitting diode (LED) lighting device having multiple driving stages, comprising:
a first luminescent device driven by a rectified alternative-current (AC) voltage and configured to provide light according to a first current;
a first current sensing element configured to provide a first feedback voltage associated with the first current;
a first current regulator configured to provide a first regulating current setting according to the first feedback voltage and a line voltage detection voltage associated with the rectified AC voltage, wherein a waveform of the first regulating current setting follows a waveform of the rectified AC voltage, the first current regulator including:
a first pin coupled in series to the first luminescent device;
a second pin;
a third pin coupled to receive the first feedback voltage;
a fourth pin coupled to receive the line voltage detection voltage;
a voltage sensing circuit coupled to the second pin and the fourth pin, and configured to generate a first control signal according to the line voltage detection voltage;
a first current controller coupled to the second pin and the third pin, and configured to generate a second control signal according to the first control signal and the first feedback voltage; and
a first controllable current source coupled to the first pin and the third pin, and configured to regulate the first current according to the second control signal so that the first current does not exceed a value of the first regulating current and the waveform of the first current follows a waveform of the line voltage detection voltage;
a second luminescent device coupled in series to the first luminescent device and configured to provide light according to a second current;
a second current sensing element configured to provide a second feedback voltage associated with the second current; and
a second current regulator coupled in parallel to the second luminescent device and configured to provide a constant second regulating current setting according to the second feedback voltage.
2. The LED lighting device of claim 1 , wherein the first current regulator further includes:
a fifth pin coupled to the rectified AC voltage; and
an internal regulator coupled to the fifth pin for supplying power to the first current regulator.
3. The LED lighting device of claim 1 , wherein:
the first current regulator further includes:
a resistor;
a capacitor;
a fifth pin coupled to the rectified AC voltage;
a sixth pin coupled to receive a root mean square (RMS) of the rectified AC voltage from the fourth pin;
an internal regulator coupled to the fifth pin for supplying power to the first current regulator;
the fourth pin is further coupled to the second pin via the resistor and the capacitor for acquiring the RMS of the rectified AC voltage; and
the voltage sensing circuit is further coupled to the sixth pin and configured to generate the first control signal further according to a voltage established at the sixth pin.
4. The LED lighting device of claim 1 , wherein the second current regulator includes:
a fifth pin coupled to a first end of the second luminescent device;
a sixth pin coupled to a first end of the second current sensing element;
a seventh pin coupled between a second end of the second luminescent device and a second end of the second current sensing element for receiving the second feedback voltage;
a second current controller coupled to the sixth pin and the seventh pin, and configured to generate a third control signal according to the second feedback voltage; and
a second controllable current source coupled to the fifth pin and the seventh pin, and configured to regulate the second current according to the third control signal so that the second current does not exceeds the second regulating current setting.
5. The LED lighting device of claim 1 , further comprising:
a voltage-dividing circuit configured to generate the line voltage detection voltage by voltage-dividing the rectified AC voltage.
6. The LED lighting device of claim 1 , further comprising:
a third luminescent device coupled in series to the second luminescent device and configured to provide light according to a third current;
a third current sensing element configured to provide a third feedback voltage associated with the third current; and
a third current regulator coupled in parallel to the third luminescent device and configured to provide a constant third regulating current setting according to the third feedback voltage.
7. The LED lighting device of claim 1 further comprising a power supply circuit configured to provide the rectified AC voltage.
8. The LED lighting device of claim 1 wherein the first current sensing element and the second current sensing element are resistors.
9. A light-emitting diode (LED) lighting device having multiple driving stages, comprising:
a first luminescent device driven by a rectified alternative-current (AC) voltage and configured to provide light according to a first current;
a first current sensing element configured to provide a first feedback voltage associated with the first current;
a first current regulator configured to provide a first regulating current setting according to the first feedback voltage and a line voltage detection voltage associated with the rectified AC voltage, wherein a waveform of the first regulating current setting follows a waveform of the rectified AC voltage;
a second luminescent device coupled in series to the first luminescent device and configured to provide light according to second current;
a second current sensing element configured to provide a second feedback voltage associated with the second current; and
a second current regulator coupled in parallel to the second luminescent device and configured to provide a constant second regulating current setting according to the second feedback voltage, the second current regulator including:
a first pin coupled to a first end of the second luminescent device;
a second pin coupled to a first end of the second current sensing element;
a third pin coupled between a second end of the second luminescent device and a second end of the second current sensing element for receiving the second feedback voltage;
a current controller coupled to the second pin and the third pin, and configured to generate a control signal according to the second feedback voltage; and
a controllable current source coupled to the first pin and the third pin, and configured to regulate the second current according to the control signal so that the second current does not exceeds the second regulating current setting.